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+
+# Recommendation
+
+# **ITU-T L.1004 (07/2025)**
+
+SERIES L: Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant
+
+E-waste and circular economy
+
+---
+
+## **Universal fast-charging solution for mobile terminals**
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features the letters "ITU" in a bold, blue, sans-serif font, superimposed on a stylized globe icon with intersecting lines.
+
+ITU logo
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+## **Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant**
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| OPTICAL FIBRE CABLES                                   | L.100-L.199          |
+| Cable structure and characteristics                    | L.100-L.124          |
+| Cable evaluation                                       | L.125-L.149          |
+| Guidance and installation technique                    | L.150-L.199          |
+| OPTICAL INFRASTRUCTURES                                | L.200-L.299          |
+| Infrastructure including node elements (except cables) | L.200-L.249          |
+| General aspects and network design                     | L.250-L.299          |
+| MAINTENANCE AND OPERATION                              | L.300-L.399          |
+| Optical fibre cable maintenance                        | L.300-L.329          |
+| Infrastructure maintenance                             | L.330-L.349          |
+| Operation support and infrastructure management        | L.350-L.379          |
+| Disaster management                                    | L.380-L.399          |
+| PASSIVE OPTICAL DEVICES                                | L.400-L.429          |
+| MARINIZED TERRESTRIAL CABLES                           | L.430-L.449          |
+| <b>E-WASTE AND CIRCULAR ECONOMY</b>                    | <b>L.1000-L.1199</b> |
+| POWER FEEDING AND ENERGY STORAGE                       | L.1200-L.1299        |
+| ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES | L.1300-L.1399        |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES  | L.1400-L.1499        |
+| ADAPTATION TO CLIMATE CHANGE                           | L.1500-L.1599        |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES        | L.1600-L.1699        |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                    | L.1700-L.1799        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.1004
+
+## Universal fast-charging solution for mobile terminals
+
+## Summary
+
+Recommendation ITU-T L.1004 is applicable to the universal fast-charging solution (UFCS) for mobile and wireless devices. This Recommendation defines the overall framework of the solution for mobile terminals and the role of each part. The communication flow between each part of the UFCS and the key functions in it are also described. The Recommendation specifies requirements for various aspects such as system, safety, electromagnetic compatibility, material, eco-environment and energy efficiency. The higher interoperability brings important environmental benefits including reduced electronic waste and use of materials and energy, a smaller carbon footprint through lesser use of energy and materials to produce chargers and being able to sell devices without a charger.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T L.1004   | 2025-07-29 | 5           | 11.1002/1000/16407 |
+
+## Keywords
+
+Cable, mobile terminals, sink, source, universal fast-charging solution.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2025
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                           | Page |
+|---------------------------------------------------------------------------|------|
+| 1 Scope.....                                                              | 1    |
+| 2 References.....                                                         | 1    |
+| 3 Definitions .....                                                       | 2    |
+| 3.1 Terms defined elsewhere .....                                         | 2    |
+| 3.2 Terms defined in this Recommendation.....                             | 2    |
+| 4 Abbreviations and acronyms .....                                        | 2    |
+| 5 Conventions .....                                                       | 3    |
+| 6 Advantages of universal solution for consumers and the environment..... | 3    |
+| 7 Overview of the Universal Fast Charging Solution.....                   | 4    |
+| 7.1 Overall Framework.....                                                | 4    |
+| 7.2 Basic role of each part .....                                         | 4    |
+| 8 Communication flows of the Universal Fast Charging Solution.....        | 5    |
+| 8.1 Overall communication flow .....                                      | 5    |
+| 8.2 Key functions and elements in a communication flow .....              | 7    |
+| 9 General requirements.....                                               | 7    |
+| 9.1 System requirements .....                                             | 7    |
+| 9.2 Safety requirements .....                                             | 8    |
+| 9.3 Electromagnetic compatibility requirements.....                       | 8    |
+| 9.4 Material requirements.....                                            | 8    |
+| 9.5 Eco-environmental requirements.....                                   | 8    |
+| 9.6 Energy efficiency design .....                                        | 9    |
+| Appendix I – Best practice.....                                           | 10   |
+| Bibliography.....                                                         | 11   |
+
+
+
+# Recommendation ITU-T L.1004
+
+## Universal fast-charging solution for mobile terminals
+
+# 1 Scope
+
+This Recommendation is applicable to the universal fast-charging solution (UFCS) for mobile and wireless devices, and specifically to wired fast charging. This Recommendation defines the overall framework of the solution and the role of each part. The communication flow between each part of UFCS and the key functions are also described. The Recommendation also specifies requirements for various aspects such as system, safety, electromagnetic compatibility (EMC), material, co-environment and energy efficiency.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [[ITU-T K.74](#)] Recommendation ITU-T K.74 (2015), *Electromagnetic compatibility, resistibility and safety requirements for home network devices*.
+- [[ITU-T K.136](#)] Recommendation ITU-T K.136 (2022), *Electromagnetic compatibility requirements for radio telecommunication equipment*.
+- [[ITU-T K.137](#)] Recommendation ITU-T K.137 (2022), *Electromagnetic compatibility requirements and measurement methods for wireline telecommunication network equipment*.
+- [[ITU-T L.1023](#)] Recommendation ITU-T L.1023 (2023), *Assessment method for circularity performance scoring*.
+- [[ITU-T L.1400](#)] Recommendation ITU-T L.1400 (2023), *Overview and general principles of methodologies for assessing the environmental impact of information and communication technologies*.
+- [[ITU-T L.1410](#)] Recommendation ITU-T L.1410 (2024), *Methodology for environmental life cycle assessments of information and communication technology goods, networks and services*.
+- [CISPR 32] IEC, CISPR Publication 32:2015, *Electromagnetic compatibility of multimedia equipment – Emission requirements*.
+- [CISPR 35] IEC, CISPR Publication 35:2016, *Electromagnetic compatibility of multimedia equipment – Immunity requirements*.
+- [IEC 60335-1] IEC 60335-1:2020, *Household and similar electrical appliances – Safety – Part 1: General requirements*.
+- [IEC 62368-1] IEC 62368-1:2023, *Audio/video, information and communication technology equipment – Part 1: Safety requirements*.
+
+|             |                                                                                                         |
+|-------------|---------------------------------------------------------------------------------------------------------|
+| [ISO 14040] | ISO 14040:2006, <i>Environmental management – Life cycle assessment – Principles and framework</i> .    |
+| [ISO 14044] | ISO 14044:2006, <i>Environmental management – Life cycle assessment – Requirements and guidelines</i> . |
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 charger** [b-ITU-T L.1000]: A common term used to describe the power adapter for the mobile terminal or other hand-held ICT devices used to apply power to the battery.
+
+**3.1.2 power adapter** [b-ITU-T L.1000]: The equipment that converts mains AC power voltage at the input to low DC power voltage at the output, or the equipment which transfers DC power supply, e.g., car voltage to another low voltage of DC power output.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 fast charging**: A process that charges a device's battery in a relatively short time.
+
+**3.2.2 fast-charging mode**: A charging mode in which the charging power exceeds 15 W.
+
+**3.2.3 fast-charging protocol**: A communication protocol between the source and sink that enables the fast-charging mode.
+
+**3.2.4 fast-charging system**: A power delivery system consisting of a source, cable and sink that support a fast-charging mode and fast-charging protocol.
+
+**3.2.5 universal fast-charging solution**: A standardization initiative that defines a unified fast-charging solution for devices of different brands.
+
+**3.2.6 source**: A device that provides power to a sink through a cable such as a power adapter.
+
+**3.2.7 sink**: A device that receives power from a source through a cable, such as a mobile terminal.
+
+**3.2.8 cable electronic label**: A chip that stores a cable's key characteristics such as its power delivery capability and data transmission capability.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|         |                               |
+|---------|-------------------------------|
+| BBP     | Benzyl Butyl Phthalate        |
+| CRC     | Cyclic Redundancy Check       |
+| DBP     | Dibutyl Phthalate             |
+| DC      | Direct Current                |
+| DIBP    | Diisobutyl Phthalate          |
+| DIDP    | Diisodecyl Phthalate          |
+| EMC     | Electromagnetic Compatibility |
+| e-waste | electronic waste              |
+| PBB     | Polybrominated Biphenyl       |
+
+|      |                                  |
+|------|----------------------------------|
+| PBDE | Polybrominated Diphenyl Ether    |
+| UFCS | Universal Fast-Charging Solution |
+| VBUS | Voltage Bus                      |
+
+# 5 Conventions
+
+None.
+
+# 6 Advantages of universal solution for consumers and the environment
+
+As mobile terminals become more and more intelligent and feature-rich, the power consumption rate is increasing rapidly. The popularity of fast charging has greatly empowered consumers as technology has developed. As the fast-charging protocols of different manufacturers are not fully compatible with each other, users may experience maximum charging speed only when using original chargers and cables with their mobile terminals. When a user changes his/her mobile terminal to another brand, it may not be possible to use the original charger and cable for fast charging, let alone the maximum speed.
+
+The universal fast-charging solution (UFCS) defined in this Recommendation can support several voltage-amperage combinations and powers higher than 15 W.
+
+The UFCS will effectively improve the compatibility of fast-charging functionality between different brands of products, benefiting consumers and protecting the environment.
+
+- **Enhanced user experience:** The realization of efficient and fast charging between interoperable power supplies and terminals of different brands can provide consumers with a more convenient and efficient user experience as they do not need to consider whether their mobile terminals, power supplies and accessories are of the same brand or not.
+- **Reduced supply chain costs:** The risk and cost of developing UFCS power supply chips and accessories for the upstream and downstream supply chain is very high due to the lack of unified charging protocols. This Recommendation will facilitate a unified ecosystem which will help upstream and downstream manufacturers in the supply chain avoid risks, reduce costs, increase efficiency and reduce carbon emissions when designing and manufacturing products.
+- **Reduced e-waste:** UFCS enables users to purchase new mobile terminals without a new charger and cable and to keep using their existing (UFCS) power supplies and accessories to charge their new UFCS terminals, or even use a single power supply and accessories for multiple devices. As a result, consumer e-waste and environmental impact is reduced. For the whole of society, it will improve the efficiency of resource utilization and more economical resources.
+
+# 7 Overview of the universal fast-charging solution
+
+## 7.1 Overall framework
+
+The key to the universal fast-charging solution is to define a unified fast-charging protocol which provides a safe, convenient and efficient fast-charging mode between devices of different brands. There shall be at least five parts in a unified fast-charging protocol for communication between the source, the sink and the cable, as shown in Figure 1.
+
+NOTE – The cable connects the source and sink, which shall have at least three types of lines – voltage bus (VBUS), ground and signal lines – for protocol communication. If the cable supports a current level that exceeds the UFCS threshold, it shall incorporate a UFCS cable electronic label.
+
+![Figure 1 – Overall framework diagram showing Source, Cable, and Sink components and their layers.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+The diagram illustrates the overall framework for UFCS, divided into three main components: Source, Cable, and Sink.
+
+- Source:** Contains an **Application layer** connected to a **Power output** block. Below the Application layer is a **Protocol layer** (containing **Protocol interaction**, **Authentication**, and **Safety test**), which connects to a **Physical layer**. The Physical layer connects to an **Interface** block.
+- Cable:** Connects the Source Interface to the Sink Interface. It contains **VBUS** (power lines), a **Cable electronic label**, and **Differential signal lines** (data lines).
+- Sink:** Contains an **Interface** block connected to a **Power input** block, which is connected to the **Application layer**. Similar to the Source, it has a **Protocol layer** (containing **Protocol interaction**, **Authentication**, and **Safety test**) connected to a **Physical layer**, which in turn connects to the Interface block.
+
+Arrows indicate the flow of power and data between these components. A label **L.1004(25)** is present in the bottom right corner of the diagram.
+
+Figure 1 – Overall framework diagram showing Source, Cable, and Sink components and their layers.
+
+**Figure 1 – Overall framework**
+
+## 7.2 Basic role of each part
+
+- **Physical layer:** Defines the signal technology for UFCS required for interoperability between UFCS devices. Each source and sink have a transmitter and receiver pair that communicates across a cable.
+
+The transmitter performs the following functions:
+
+- Receives data packet from the protocol layer;
+- Calculates and appends a cyclic redundancy check (CRC);
+- Encodes the data packet including CRC;
+- Transmits the data packet to the sink across the cable.
+
+The receiver performs the following functions:
+
+- Receives the data packet including CRC;
+- Validates the data and CRC.
+
+- **Protocol layer:** Connects the source and sink for information exchange, provides the interface for the application layer to transmit command and data, and passes the received command and data to the application layer for processing. According to the information interaction needs between devices, the protocol layer defines the message formats, message types and their working mechanism. To ensure the reliability of message transmission, the protocol layer also defines the processing status and timing of message transmitting and receiving, as well as the exception handling process.
+
+It defines the following functions:
+
+- The construction and use of messages;
+- Time sequence of message transmitting, receiving and processing;
+- Use of timers and timeout values;
+- Use of counters and message retry;
+- Error handling;
+- Reset operation.
+
+- **Application layer:** Defines aspects including policy control, authentication, source information reporting, source protection and cable identification. It describes the protocol identification mechanism, protocol application strategy and charging safety management of the sink and the source in different scenarios to synchronize the information on both sides to deliver a fast-charging experience and ensure safety.
+
+The source performs the following functions:
+
+- Identify protocol type;
+
+- Identify cable type;
+- Negotiate power output mode;
+- Report communication exception information to sink.
+
+The sink performs the following functions:
+
+- Identify protocol type;
+- Identify cable type;
+- Choose protocol type;
+- Negotiate power input mode;
+- Validate the identity of the source.
+
+- **Power output/power input:** Defines the range of the output power and various power rules, such as dynamic regulation rules, steady-state accuracy rules, source power rules and troubleshooting rules of the output power, to ensure that the fast-charging system performs the power regulation in a safe and efficient way.
+
+The source performs the following functions:
+
+- Negotiate power output mode;
+- Regulate power output mode;
+- Request change power output mode;
+- Error handling.
+
+The sink performs the following functions:
+
+- Negotiate power input mode;
+- Regulate power input mode;
+- Request change power input mode;
+- Error handling.
+
+- **Interface:** Defines the VBUS, ground and signal pins. It can support both full-duplex communication and half-duplex communication.
+
+# 8 Communication flows of the universal fast-charging solution
+
+## 8.1 Overall communication flow
+
+The overall communication flow of a unified fast-charging protocol is shown in Figure 2. It includes protocol identification, source device information, source output capability, cable information, authentication, power change and other communication processes.
+
+![Flowchart showing the overall communication flow between a Sink and a Source.](d4af765160d04ecef538e5066006dc77_img.jpg)
+
+```
+
+  graph TD
+    subgraph Sink
+      S_Start([Start]) --> S_Handshake[Sink Handshake detection]
+      S_Handshake --> S_Protocol[Sink Protocol identification]
+      S_Protocol --> S_GetInfo[Get source device information]
+      S_GetInfo --> S_GetCap[Get source output capability]
+      S_GetCap --> S_DecCable{Get cable information?}
+      S_DecCable -- Yes --> S_ReadCable[Sink Read cable information]
+      S_DecCable -- No --> S_DecAuth{Authentication?}
+      S_ReadCable --> S_DecAuth
+      S_DecAuth -- Yes --> S_Auth[Sink Authentication]
+      S_DecAuth -- No --> S_DecPower{Power change?}
+      S_Auth --> S_DecPower
+      S_DecPower -- Yes --> S_PowerReq[Sink Power change request]
+      S_DecPower -- No --> S_PowerResp[Sink Power change response]
+      S_PowerReq --> S_PowerResp
+      S_PowerResp --> S_Other[Other flows]
+      S_Other --> S_DecPower
+    end
+
+    subgraph Source
+      Src_Start([Start]) --> Src_Handshake[Source Handshake detection]
+      Src_Handshake --> Src_Protocol[Sink Protocol identification]
+      Src_Protocol --> Src_DeviceInfo[Source device information report]
+      Src_DeviceInfo --> Src_OutputCap[Source output capability report]
+      Src_OutputCap --> Src_ReadCable[Source Read cable information]
+      Src_ReadCable --> Src_Auth[Source Authentication]
+      Src_Auth --> Src_PowerResp[Source Power change response]
+      Src_PowerResp --> Src_DecPower{Power change?}
+      Src_DecPower -- Yes --> Src_PowerReq[Source Power change request]
+      Src_DecPower -- No --> Src_Other[Other flows]
+      Src_PowerReq --> Src_Other
+      Src_Other --> Src_PowerResp
+    end
+
+    S_Handshake <--> Src_Handshake
+    S_Protocol <--> Src_Protocol
+    S_GetInfo <--> Src_DeviceInfo
+    S_GetCap <--> Src_OutputCap
+    S_ReadCable <--> Src_ReadCable
+    S_Auth <--> Src_Auth
+    S_PowerReq <--> Src_PowerResp
+    S_PowerResp <--> Src_PowerReq
+    S_Other <--> Src_Other
+  
+```
+
+Flowchart showing the overall communication flow between a Sink and a Source.
+
+**Figure 2 – Overall communication flow**
+
+NOTE – The sequence of steps before source output capability is fixed, and the sequence of steps after that can vary according to the manufacturer's needs.
+
+6 Rec. ITU-T L.1004 (07/2025)
+
+## 8.2 Key functions and elements in a communication flow
+
+- **Handshake detection:** When the source and sink are connected via a cable, the sink shall initiate the handshake detection flow. The sink sends the appropriate message on the signal line, and the source continuously monitors this signal line. Once the source detects the message sent by the sink on the signal line, it shall switch to the UFCS fast-charging mode within the required time. After sending the message, the sink shall continuously monitor the signal line level within the required time. Once the sink detects a high level, it shall switch the signal line to the UFCS fast-charging mode within the required time.
+- **Protocol identification:** After switching to UFCS mode, the sink shall send the appropriate message to the source within the required time. Upon receiving this message, the source shall reply to the sink within the required time. The sink confirms that the reply message from the source is correct, indicating a successful identification of an end-to-end UFCS fast-charging capability.
+- **Source device information:** After the UFCS fast-charging capability has been identified successfully, the sink shall send a message to the source, requesting information related to the source's hardware and software capabilities. Upon receiving the request message, the source shall reply with the device information message within the required time.
+- **Source output capability:** After the UFCS fast-charging capability has been successfully identified, the sink shall send a message to the source to obtain its voltage and current output capabilities. Upon receiving the request message, the source shall reply with an output capabilities message within the required time.
+- **Cable information:** Both the source and the sink can send a message to the cable chip in order to obtain the cable's device information and transmission capability, including the cable's impedance, maximum voltage and maximum current carrying capacity. Upon receiving the request message, the cable electronic label shall reply with a cable information message within the required time.
+- **Authentication:** An optional feature used to identify secure and reliable sources and sinks. After successful authentication, higher charging power can be achieved. When UFCS charging power exceeds a set threshold, the sink should perform authentication, with the threshold being defined by the manufacturer. The source or the sink can send a verify request message to the other entity to request authentication; upon receiving the consent response, the authentication timer will be started. If the verify message has not been received within the required time, the authentication process will be exited and it is regarded to have failed.
+- **Power change:** A mandatory feature used to change the output power. If the output power of the source changes after entering UFCS fast-charging mode, the source shall actively send a power change message to inform the sink. The sink determines the power adjustment strategy based on the received message. The sink can send one or multiple request messages, asking the source to reduce the maximum output current to within the range notified by the power change message all at once or gradually.
+- **Other flows:** Including pull-out detection, impedance detection, abnormality detection, manufacturer-defined flow, etc. These flows ensure a more stable and safer fast-charging experience.
+
+# 9 General requirements
+
+## 9.1 System requirements
+
+The UFCS system specified in this Recommendation consists of a source, cable and sink. The basic configuration of each part in this system is described in Annex A.1 of [b-ITU-T L.1000]. To ensure the reliability and safety of fast charging, the UFCS system shall support sufficient protection
+
+functions mechanisms. The sink supports the retrieval of cable information and real-time impedance detection functions. The source supports functions such as overvoltage protection, overcurrent protection, overtemperature protection, hard reset, soft reset and communication timeout protection. The cable supporting current exceeding the threshold incorporates cable electronic label to provide information such as power delivery capabilities and so on for communications.
+
+## 9.2 Safety requirements
+
+The safety requirements for sink and cables shall be in accordance with the standards of the target market and international standards. For example, in the field of audio-video and ICT products, the electrical and electronic products constituting the charging system shall be in accordance with [IEC 62368-1] in order to ensure the safety of people and property. Similarly, home network devices shall be in accordance with the safety related part of [ITU-T K.74]. Household and similar electrical appliances shall be in accordance with [IEC 60335-1]. The safety of mobile terminal batteries must be considered. [b-IEEE 1725] presents the safety design of rechargeable lithium-ion batteries for mobile terminal applications, focusing on overall safety, (including that of the power adapter, the host and the battery).
+
+## 9.3 EMC requirements
+
+The UFCS system shall comply with the emission requirements described in [CISPR 32]. It should also comply with the immunity requirements described in [CISPR 35], [ITU-T K.74], [ITU-T K.136] and [ITU-T K.137]. Any national regulations override the EMC requirements of this Recommendation.
+
+## 9.4 Material requirements
+
+Mobile hand-held terminals (cell phones, tablets, etc.), cables, chargers and power banks commonly found in UFCS systems are products that are easily accessible to consumers and are also consumer products with a large global stock. For the sustainable and green development of electrical and electronic products, their sales packaging should be made of materials which are renewable, easy to recycle and dismantle, and simple to assemble.
+
+Electronic and electrical products contained in a UFCS system are subject to the requirements of hazardous substance restrictions, in which the content of lead (Pb), mercury (Hg), hexavalent chromium (Cr<sup>6+</sup>), polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs) and the four phthalates (Diisodecyl Phthalate (DIDP), diisobutyl phthalate (DIBP), dibutyl phthalate (DBP), benzyl butyl phthalate (BBP)) shall not exceed 0.1% (1000 ppm). Cadmium (Cd) content shall not exceed 0.01% (100 ppm). Corresponding exemptions and exceptions will be implemented according to the regulatory policies of each country or region.
+
+The [b-IEC 62321] series of standards for determination of certain substances in electrotechnical product provides relevant guidance for this.
+
+## 9.5 Eco-environmental requirements
+
+Environmental criteria are gaining importance in all aspects of electronic design. The circular economy aspect needs to be considered during the design, based on the guidance and assessment method defined in [ITU-T L.1023]. A life cycle assessment (LCA) should be established in compliance with [ISO 14040], [ISO 14044], [ITU-T L.1400] and [ITU-T L.1410].
+
+NOTE – The ITU-T L.1400 series of standards define an important methodology based on full LCA. Many basic methods can be applied by reference.
+
+## **9.6 Energy efficiency design**
+
+UFCS shall apply appropriate thermal management in order to avoid battery overheating or waste of energy and to ensure safe charging. At the same time, an energy-efficient design can reduce the loss of energy in the battery and prolong the lifetime of the mobile terminal.
+
+The terminal is recommended to adjust power consumption based on load, and optimize energy efficiency in order to improve the durability of the UFCS system. The combination of energy-efficient design and production will reduce the carbon footprint of mobile terminals. Documents such as [b-DOE] and [b-Bel] provide information on energy efficiency, including no-load requirements and technical feasibility.
+
+## Appendix I
+
+## Best practice
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The goal of a good universal fast-charging solution is to reduce energy consumption and e-waste, both in terms of facilitating the resolution of e-waste issues in existing applications and in terms of addressing environmental issues in a wider range of applications in the future. The solution should focus on consumer convenience and should be compatible and scalable while maintaining safety. The excellent universal solution should be adopted by more organizations to achieve universal roles, have test methods to validate it and be market tested. The China UFCS programme [b-T/CCSA 668|T/TAF 266], which is widely used in China, is a best practice.
+
+The China UFCS programme [b-T/CCSA 668|T/TAF 266] is distinguished by the following features:
+
+- It is specialized in charging: it only pulls through the communication protocol to achieve communication, without any damage to the system, with fully verified and mature technologies and solutions, and strong compatibility.
+- It is not limited to specific interfaces, has an efficient full-duplex bus and security measures such as authentication and path impedance detection, and it regulates voltage and current more accurately. These technical advantages will strongly support UFCS to move towards a broader industrial space. It is not only suitable for mobile terminal equipment in traditional consumer electronics such as mobile phones, tablet PCs and notebooks, but also can be applied in the field of mobile terminals with higher operational voltage, and even in the fast charging of electric bicycles. The future application areas are extremely broad.
+- Not only available for USB Type C [b-IEC 62680-1-3], it is also perfectly compatible with commonly used interfaces such as USB-A [b-IEC 62680-2-1] and Micro-B [b-USB-IF]. In China and even around the world, there are still a large number of devices with the legacy interfaces mentioned above. It is therefore compatible with the previous charging industry ecosystem, and can greatly reduce e-waste and alleviate existing environmental problems.
+- It contains complete test methods and use cases for functionality, safety and compatibility, which have guaranteed the reliability of the UFCS. Detailed and comprehensive test methods are available in [b-T/CCSA 394|T/TAF 092].
+- It is widely used in the market. For example, in mobile terminals, China's leading brands are compatible with and use the UFCS protocol. The large number of products using UFCS in the China market proves the reliability and security of the programme. The solution facilitates consumers to use different brands of products and obtain a fast-charging experience. At the same time, it greatly reduces the impact on the environment.
+
+The case in this section is for reference only and this section does not mandate the use of a certain UFCS. It is up to the market to decide on the best universal fast-charging solution. However, it is expected that more manufacturers can choose excellent universal solutions in order to reduce their development costs and to respond to consumer needs, while reducing the e-waste problem caused by incompatibility, and to assume the social responsibility of protecting the environment.
+
+## Bibliography
+
+- [b-ITU-T L.1000] Recommendation ITU-T L.1000 (2019), *Universal power adapter and charger solution for mobile terminals and other hand-held ICT devices.*
+- [b-IEC 62321] IEC 62321 Series, *Determination of certain substances in electrotechnical products.*
+- [b-IEC 62680-1-3] IEC 62680-1-3:2024, *Universal serial bus interfaces for data and power – Part 1-3: Common components – USB Type-C® Cable and Connector Specification.*
+- [b-IEC 62680-2-1] IEC 62680-2-1:2015, *Universal serial bus interfaces for data and power – Part 2-1: Universal Serial Bus Specification, Revision 2.0.*
+- [b-IEEE 1725] IEEE 1725-2021, *IEEE Standard for Rechargeable Batteries for Mobile Phones.*
+- [b-Bel] Bel (2020), *Efficiency Standards for External Power Supplies.* <<http://www.cui.com/efficiency-standards>>
+- [b-DOE] United States Department of Energy (2014), *Energy Conservation Program: Energy Conservation Standards for External Power Supplies.* <[https://www.energy.gov/sites/prod/files/2014/02/f7/eps\\_ecs\\_final\\_rule.pdf](https://www.energy.gov/sites/prod/files/2014/02/f7/eps_ecs_final_rule.pdf)>
+- [b-T/CCSA 394|T/TAF 092] T/CCSA 394|T/TAF 092:2024, *Universal fast charging testing methods for mobile devices.*
+- [b-T/CCSA 668|T/TAF 266] T/CCSA 668|T/TAF 266:2025, *Universal fast charging requirement for mobile devices (Phase 2).*
+- [b-USB-IF] USB Implementers Forum (2007), *Micro-USB Cables and Connectors Specification V1.01.*
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|          |                                                                                                                                                                  |
+|----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A | Organization of the work of ITU-T                                                                                                                                |
+| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F | Non-telephone telecommunication services                                                                                                                         |
+| Series G | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H | Audiovisual and multimedia systems                                                                                                                               |
+| Series I | Integrated services digital network                                                                                                                              |
+| Series J | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K | Protection against interference                                                                                                                                  |
+| Series L | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O | Specifications of measuring equipment                                                                                                                            |
+| Series P | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R | Telegraph transmission                                                                                                                                           |
+| Series S | Telegraph services terminal equipment                                                                                                                            |
+| Series T | Terminals for telematic services                                                                                                                                 |
+| Series U | Telegraph switching                                                                                                                                              |
+| Series V | Data communication over the telephone network                                                                                                                    |
+| Series X | Data networks, open system communications and security                                                                                                           |
+| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z | Languages and general software aspects for telecommunication systems                                                                                             |

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+
+
+# Recommendation
+
+## **ITU-T L.1018 (07/2025)**
+
+SERIES L: Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant
+
+E-waste and circular economy
+
+---
+
+## **Specification for the durability assessment of mobile telecommunication terminals**
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+### **Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant**
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| OPTICAL FIBRE CABLES                                   | L.100-L.199          |
+| Cable structure and characteristics                    | L.100-L.124          |
+| Cable evaluation                                       | L.125-L.149          |
+| Guidance and installation technique                    | L.150-L.199          |
+| OPTICAL INFRASTRUCTURES                                | L.200-L.299          |
+| Infrastructure including node elements (except cables) | L.200-L.249          |
+| General aspects and network design                     | L.250-L.299          |
+| MAINTENANCE AND OPERATION                              | L.300-L.399          |
+| Optical fibre cable maintenance                        | L.300-L.329          |
+| Infrastructure maintenance                             | L.330-L.349          |
+| Operation support and infrastructure management        | L.350-L.379          |
+| Disaster management                                    | L.380-L.399          |
+| PASSIVE OPTICAL DEVICES                                | L.400-L.429          |
+| MARINIZED TERRESTRIAL CABLES                           | L.430-L.449          |
+| <b>E-WASTE AND CIRCULAR ECONOMY</b>                    | <b>L.1000-L.1199</b> |
+| POWER FEEDING AND ENERGY STORAGE                       | L.1200-L.1299        |
+| ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES | L.1300-L.1399        |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES  | L.1400-L.1499        |
+| ADAPTATION TO CLIMATE CHANGE                           | L.1500-L.1599        |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES        | L.1600-L.1699        |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                    | L.1700-L.1799        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.1018
+
+## Specification for the durability assessment of mobile telecommunication terminals
+
+## Summary
+
+Recommendation ITU-T L.1018 describes the importance of improving the durability of mobile telecommunication terminals at different stages of the product life cycle. A durability assessment method for mobile telecommunication terminals is given, including specific suggestions for improving durability in different evaluation dimensions. Finally, through the development of product durability evaluation indicators and grading, this Recommendation provides specific guidance references for users to assess the durability of mobile telecommunication terminals.
+
+The EN 45552:2020 and EN 45553:2020 standards serve as comprehensive methodologies for assessing energy-related products for their durability and manufacturing capability, respectively. These standards have a broader scope and are considered universal benchmarks. On the other hand, Recommendation ITU-T L.1023 focuses on an assessment method for circularity scoring of information and communication technology (ICT) goods, employing different assessment dimensions compared with this Recommendation. Based on the above research, this Recommendation focuses on evaluating the durability of mobile telecommunication terminal products throughout their entire life cycle. It combines the characteristics of mobile terminal products and methods to improve durability during product design, production, use and recycling. It also evaluates the durability of mobile telecommunication terminal products based on environmental adaptability, maintenance and repair of the entire machine and spare parts, recycling and reuse, system management, data security and manufacturer operation. This evaluation content is more detailed than general international standards and differs from other standards in its evaluation dimensions and methods to meet industry's specific green development needs.
+
+## History \*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T L.1018   | 2025-07-29 | 5           | 11.1002/1000/16409 |
+
+## Keywords
+
+Durability assessment, mobile telecommunication terminals.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2025
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                               | Page |
+|-------------------------------------------------------------------------------|------|
+| 1 Scope.....                                                                  | 1    |
+| 2 References.....                                                             | 1    |
+| 3 Definitions .....                                                           | 1    |
+| 3.1 Terms defined elsewhere .....                                             | 1    |
+| 3.2 Terms defined in this Recommendation.....                                 | 2    |
+| 4 Abbreviations and acronyms .....                                            | 2    |
+| 5 Conventions .....                                                           | 2    |
+| 6 Introduction.....                                                           | 2    |
+| 7 Improve the durability of mobile telecommunication terminals .....          | 3    |
+| 7.1 Design stage of mobile telecommunication terminals.....                   | 3    |
+| 7.2 Manufacturing stage of mobile telecommunication terminals .....           | 3    |
+| 7.3 Using stage of mobile telecommunication terminals .....                   | 3    |
+| 7.4 Recycling stage of mobile telecommunication terminals.....                | 3    |
+| 8 Durability assessment method of mobile telecommunication terminals .....    | 3    |
+| 8.1 Durability analysis.....                                                  | 3    |
+| 8.2 Durability evaluation dimensions.....                                     | 4    |
+| 9 Durability assessment indicator of mobile telecommunication terminals ..... | 8    |
+| 9.1 Evaluation indicator.....                                                 | 8    |
+| 9.2 Level assessment .....                                                    | 13   |
+| 10 Documenting the assessment of durability .....                             | 13   |
+| Bibliography.....                                                             | 14   |
+
+
+
+# Recommendation ITU-T L.1018
+
+## Specification for the durability assessment of mobile telecommunication terminals
+
+## 1 Scope
+
+This Recommendation focuses on establishing a durability assessment standard to improve the material utilization efficiency and reduce the carbon emissions of mobile telecommunication terminal products during the life cycle. It also focuses on establishing specification for the durability assessment of mobile telecommunication terminals. The assessment indicators for mobile telecommunication terminals include environmental applicability, maintenance and repair of the entire device and its accessories, recycling and reuse, system management, data security and manufacturer operation.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[EN 45552] EN 45552:2020, *General method for the assessment of the durability of energy-related products*.
+
+[EN 45553] EN 45553:2020, *General method for assessing the ability of an energy-related product to be remanufactured*.
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+This Recommendation uses the following term defined elsewhere:
+
+**3.1.1 disassembly** [b-EN 45554]: Process whereby a product is taken apart in such a way that it could subsequently be reassembled and made operational.
+
+**3.1.2 durability** [EN 45552]: Ability < of a part or a product > to function as required, under defined conditions of use, maintenance and repair, until a final limiting state is reached.
+
+NOTE 1 – The degree to which maintenance and repair are within scope of durability will vary by product or product group.
+
+NOTE 2 – The final limiting state has to be defined by the user of [EN 45552].
+
+**3.1.3 life cycle** [b-ISO 14040]: Consecutive and interlinked stages of a product system, from raw material acquisition or generation from natural resources to final disposal.
+
+**3.1.4 reliability** [EN 45552]: Probability that a product functions as required under given conditions, including maintenance, for a given duration without limiting event.
+
+NOTE 1 – The intended function(s) and given conditions are described in the user instructions provided with the product.
+
+NOTE 2 – Duration can be expressed in units appropriate to the part or product concerned, e.g., calendar time, operating cycles, distance run, etc., and the units should be clearly stated.
+
+**3.1.5 remanufacturing** [EN 45553]: Industrial process which produces a product from used products or used parts where at least one change is made which influences the safety, original performance, purpose or type of the product.
+
+**3.1.6 repair** [EN 45552]: Process of returning a faulty product to a condition where it can fulfil its intended use.
+
+## **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following term:
+
+**3.2.1 mobile telecommunication terminal**: User terminal equipment, excluding vehicle-mounted equipment, that transmits or receives voice, image and data through access to a cellular network.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                                |
+|-------|------------------------------------------------|
+| ICT   | Information and Communication Technology       |
+| DFEMA | Design Failure Mode and Effects Analysis       |
+| FMEA  | Failure Mode and Effects Analysis              |
+| FMECA | Failure Mode, Effects and Criticality Analysis |
+| PFMEA | Process Failure Modes and Effects Analysis     |
+| RRU   | Repair, Reuse, Upgrade                         |
+
+# **5 Conventions**
+
+None.
+
+# **6 Introduction**
+
+Mobile telecommunication terminals are very important for daily life and work. Currently, the rapid development of the mobile Internet is increasing the demand for these devices year by year. Consequently, their carbon emissions throughout their entire life cycle, from production to disposal, are also increasing. Given the urgent need to address global climate change and reduce carbon emissions, improving the durability of mobile telecommunication terminals is crucial to achieving a low-carbon future.
+
+At a manufacturing level, the proposal sets out clear durability targets and testing methods for the design and production of mobile telecommunication terminal products. This encourages manufacturers to use higher-quality materials and more sensible design solutions, as well as optimizing production processes to ensure products are stable and reliable in the long term. Improving the durability of mobile telecommunication terminal products can also reduce after-sales maintenance and replacement costs. This improves market retention and service life, increases product value and generates more profit for manufacturers.
+
+At the consumer level, requiring manufacturers to provide guidelines on the use and maintenance of their products, as well as relevant after-sales maintenance services, ensures that products can be restored to good condition, thus prolonging their life. At the same time, consumers are provided with quantitative information on the durability of mobile telecommunication terminal products based on their ratings. This helps consumers make more informed purchasing decisions, avoid frequent replacement due to lack of durability, and save economic and time costs.
+
+# **7 Improve the durability of mobile telecommunication terminals**
+
+## **7.1 Design stage of mobile telecommunication terminals**
+
+Manufacturers should raise awareness of product durability during the design phase of mobile telecommunication terminals. Product design is the key to improving durability before production and manufacturing. Once a product has been mass-produced, its performance is finalized and methods of improving durability are greatly reduced.
+
+## **7.2 Manufacturing stage of mobile telecommunication terminals**
+
+Product durability is closely related to the manufacturing stage. The process control and engineering management of the factory are important, including its environmental adaptability, cycle life, reliability, electromagnetic compatibility (EMC) performance and battery intermixing performance, from product finalization to mass production. At this phase, manufacturers have many opportunities to analyse and validate their products and provide better solutions to improve durability.
+
+## **7.3 Using stage of mobile telecommunication terminals**
+
+When the mobile telecommunication terminals are put onto the market and enter into the use stage, their function and endurability has already been fixed. The use of mobile telecommunication terminals should be in accordance with the method recommended by the manufacturer. The first way to improve durability in the use stage is to avoid system failure. Once the mobile telecommunication terminal breaks down, the product cannot be directly used. The second way is to slow down product performance degradation. The degradation of product performance is inevitable during the use of mobile telecommunication terminals. In this stage, consumers are supposed to use mobile telecommunication terminals correctly and develop good maintenance habits in order to improve the durability of the products.
+
+## **7.4 Recycling stage of mobile telecommunication terminals**
+
+Durable mobile telecommunication terminals usually have higher material integrity and are more easily recycled. Even if the product is eventually recovered and dismantled, the durable housing materials and components are easier to separate and re-use. This reduces loss and pollution in the recovery process while promoting resource recycling. The [EN 45553] standard can be used to assess the effective recycling and reuse of energy products and remanufacturing capabilities.
+
+# **8 Durability assessment method of mobile telecommunication terminals**
+
+## **8.1 Durability analysis**
+
+The concept of reliability can be introduced into the durability analysis process to help analysis durability. Failure Mode and Effects Analysis (FMEA), Failure Mode, Effects and Criticality Analysis (FMECA), Process Failure Modes and Effects Analysis (PFMEA), Design Failure Mode and Effects Analysis (DFEMA) or equivalent analysis may be applied to identify failure modes, failure mechanisms, failure locations and the components involved in the failure of each analysis function to assess reliability. The durability analysis should consider applicable environmental, operating conditions and performance parameters comprehensively. If feasible, the value and location of the parameters should be determined; for the dimension of durability evaluation, appropriate damage models and acceleration coefficients can be used to determine the parameters of each evaluation dimension.
+
+A durability analysis must encompass an array of performance indicators to ensure a comprehensive evaluation. The primary objective is to conduct a durability analysis of mobile telecommunication terminal products, encompassing five key aspects: environmental adaptability, maintenance and repair of the entire machine and accessories, recycling and reuse, system management and data security, and manufacturer operation.
+
+A general method for assessment can be found in the standard [EN 45552].
+
+**Table 1 – Durability assessment goals and tool examples**
+
+| Goal                                                                                        | Tool examples                                                                                                                                                                                                                                                                 |
+|---------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Improving the durability of mobile telecommunication terminals through testing and analysis | Damage modelling as well as durability calculations ([b-IEC 60605-4], [b-IEC 61709], [b-IEC 60300-3-5] and [b-IEC 62308]);<br>Environmental testing ([b-IEC 60068]);<br>Failure mode analysis: FMEA, FMECA, PFMEA, DFEMA;<br>Reliability and durability analysis ([EN 45552]) |
+
+## 8.2 Durability evaluation dimensions
+
+### 8.2.1 Environmental adaptability
+
+Environmental adaptability refers to a mobile telecommunication terminal's ability to perform all its expected functions and deliver all its promised performance under various environmental influences during its life cycle without suffering damage. The ability of these products to resist damage directly affects their durability, an important aspect of durability assessment. This component consists mainly of non-mechanical and mechanical stresses.
+
+##### 8.2.1.1 Nonmechanical stress
+
+Any mobile telecommunication terminal products are used, transported and stored under specific environmental conditions. Therefore, no situation is unaffected by environmental influences. These environments include non-mechanical stresses such as high and low temperatures, humidity, heat, salt spray, temperature cycling and rain. The state of mobile telecommunication terminal products and the effects of different environments must be fully considered when assessing them.
+
+A factor in the environmental sustainability of a company's products is the design of environmental tests, which should incorporate various protective measures for the product. The durability of the product is improved through simulation tests of extreme environments, which are used to meet the quality objectives expected in product development, design and manufacturing. Nonmechanical stress tests include but are not limited to the following:
+
+- a) Temperature test: To check if the terminal can be turned on, talk and transmit data under different temperature conditions, place the terminal under the conditions for a certain period of time. Then, check whether the terminal can be turned on, talk and transmit data.
+- b) Humidity test: Put the terminal in an environment that is always humid and hot (with a relative humidity of 90% to 95%) for a certain amount of time. Then, check if the terminal looks deformed or corroded. Also, check if the functions are normal. For example, check if the screen display is normal and if the buttons are sensitive.
+- c) Temperature change test: Quickly change the temperature many times to copy the temperature changes that could happen when the terminal is used. Then, check how the performance of the terminal changes after it has been tested a few times.
+- d) Salt spray test: Put the terminal in the salt spray environment, run the test for a certain amount of time and then check for corrosion in the terminal shell, connector and other parts. This will show whether the terminal is working properly.
+
+##### **8.2.1.2 Mechanical stress**
+
+Improving the service life of mobile telecommunication terminals requires parts and components to have higher resistance to mechanical stresses (e.g., higher resistance to accidental drops, shocks, collisions, scratches, waterproofing and dustproofing), which contributes to a longer service life. The effects of different mechanical stresses on the state of the mobile telecommunication terminal product should be fully considered in the evaluation. Mechanical stress tests include but are not limited to the following:
+
+- a) Drop test: Use a drop test machine to drop the product from different heights. Drop it from different surfaces, edges and corners to a rigid surface such as steel or the ground. Drop each surface, edge and corner several times. This will help you see whether the product will be damaged or stop working normally. It will also help you see whether the product's parts become loose or damaged.
+- b) Impact test: Use the impact test bench to create different impact pulse waveforms, set the impact acceleration and pulse duration, and conduct impact tests in different directions. Check whether the product has any unusual reboots, crashes or data loss during and after impact. Also, check whether the connectors and interfaces become loose or damaged, and if the internal and external structures remain intact.
+- c) Scratch test: Use the scratch tester to test the material of the scratch needle. This will allow you to control the scratch depth, speed and length. You can make multiple tests at different places on the product surface. After that, you can observe the depth and width of the scratches. You can also check for peeling and cracking. Finally, you can assess the influence on the product's appearance.
+- d) Dustproofing and waterproofing test: The dustproofing test involves placing the product in a dust test box and exposing it to dust for a certain amount of time, depending on the dustproofing level. The waterproofing test uses a device to spray water at different angles and at different water flow and pressure levels, depending on the waterproofing level. Look for any dust that might have entered the inside of the product. Also, check to see if there is any water inside the product and whether that has affected how it works.
+
+#### **8.2.2 Maintenance and repair of the entire terminal and accessories**
+
+##### **8.2.2.1 Maintenance supports**
+
+Mobile telecommunication terminals maintenance includes the process of restoring a defective or faulty product or system or key component to a condition to meet its intended using function (including taking apart tools, troubleshooting and fault recovery methods). The higher the repairability of the mobile telecommunication terminals and key components, the higher the durability of the products.
+
+Basic indicators focus on the completeness of technical documents, such as maintenance information, repair tips and alarms, quick diagnosis and the convenience of repairability. Maintainable information should include the following:
+
+- a) The unequivocal product identification;
+- b) A disassembly map or exploded view;
+- c) Wiring and connection diagrams, as required for failure analysis;
+- d) Electronic board diagrams, to the level of detail needed to replace parts covered by key components;
+- e) A list of necessary repair and test equipment;
+- f) Technical manual of instructions for repair;
+- g) Diagnostic fault and error information (including manufacturer-specific codes when applicable);
+
+- h) Component and diagnosis information (such as minimum and maximum theoretical values for measurements, except for personal identifiable information);
+- i) Instructions for software and firmware (including reset software);
+- j) Information on how to access data records of reported failure incidents stored on the device (where applicable and except for personal identifiable information such as related to user behaviour and location information);
+- k) The procedure for user authorization of parts replacement when required for a repair, and software tools, firmware and similar auxiliary means required for full functionality of the spare part and device after repair, such as remote or on-site authorization of serial numbers;
+- l) Information on how to access professional repair (web pages, addresses, contact details, etc).
+
+Manufacturers should pay attention to the maintainability of mobile telecommunication terminals to improve their durability. Manufacturers should improve the maintainability management of these products, prepare user manuals or maintenance manuals containing repairable information guidance, a list of common all-fault alarms and the content of the diagnosis and recovery procedures. The above content should be made publicly available, and there should be good spare parts supply and personnel training, which can expand the durability of products by improving maintainability.
+
+##### **8.2.2.2 Battery service life**
+
+The durability level of mobile telecommunication terminals is determined by battery performance, life, safety and environmental adaptability. These are core elements that cannot be ignored when evaluating the overall durability of equipment.
+
+Battery endurance directly affects the device's usage time and convenience. A high-performance, high-capacity battery can extend usage time, reduce charging frequency and improve the user experience.
+
+The charge/discharge cycle life of the battery affects the device's long-term reliability. If the battery shows significant ageing and capacity degradation over a short period, the device's utility will decrease, forcing users to replace it earlier.
+
+Battery safety is also a key factor in durability evaluations. Stable battery design and protection mechanisms prevent failures such as overheating and explosions, ensuring the device can be used safely.
+
+A battery's environmental adaptability, such as its performance in extreme temperatures, affects its durability in different usage scenarios.
+
+#### **8.2.2.3 Availability of spare parts**
+
+A spare part is a separate part that can replace a part with the same or similar function in a mobile telecommunication terminal. A part needs to be considered necessary for use if the mobile telecommunication terminal cannot function as intended without that part. The functionality of the mobile telecommunication terminal is restored or upgraded when the part is replaced by a spare part; Spare Part Type 1 is one that can be replaced by professional repair persons, and Spare Part Type 2 is for both professional repair persons and users.
+
+The availability of spare parts can be assessed in terms of the type of spare parts, the timing of their availability and their quantity.
+
+Therefore, spare parts include those in the two lists below if applicable.
+
+Spare parts are of Type 1 (if applicable): The manufacturer or authorized representative needs to provide the following spare parts, including the necessary fasteners (if not reusable), to professional maintenance personnel within a minimum period of one month of the date of placing on the market:
+
+- a) Battery or batteries;
+
+- b) Front-facing camera assembly;
+- c) Rear-facing camera assembly;
+- d) External audio connector(s);
+- e) External charging port(s);
+- f) Mechanical button(s);
+- g) Main microphone(s);
+- h) Speaker(s);
+- i) Hinge assembly;
+- j) Mechanical display folding mechanism.
+
+Spare parts are of Type 2 (if applicable): the manufacturer or authorized representative needs to provide necessary spare parts including any required fasteners (if not reusable) to professional repair persons and users within one month of the date of placing on the market:
+
+- a) Battery or batteries;
+- b) Back cover or back cover assembly, if fully removed for replacement of the battery;
+- c) Protective foil for foldable displays;
+- d) Display assembly;
+- e) Charger;
+- f) SIM tray and memory card tray, if there is an external slot for a SIM tray or memory card tray.
+
+Regarding the supply time of spare parts, the service life of mobile terminal products must be considered. After the products have been discontinued, the manufacturer should continue to provide corresponding spare parts for a certain period of time (such as 5 or 7 years) to meet users' maintenance needs.
+
+Regarding the quantity of spare parts, the manufacturer should formulate a reasonable supply plan according to market demand and product sales volume to ensure the supply meets a certain proportion of maintenance demand.
+
+#### **8.2.3 Recycling and reuse**
+
+Recycling and reuse are important indicators when evaluating the durability of mobile telecommunication handhelds.
+
+In terms of fasteners and connectors, standardized types that can be easily dismantled should be selected. Fasteners that can only be dismantled with special tools should be avoided, and priority should be given to fasteners made of recyclable materials.
+
+For dismantling convenience, product designs should be modularized so that components can easily be separated, parts replaced and materials recycled. To improve the durability and recycling rate of components, promote the recycling of resources and reduce the impact of e-waste on the environment, manufacturers need to provide detailed dismantling guidelines and supporting tools for more efficient and safer dismantling.
+
+#### **8.2.4 System management and data security**
+
+A mobile telecommunication terminal system management should be able to update and upgrade software and hardware to ensure system stability and convenience. Updates should avoid causing equipment to lag, crash or experience compatibility problems. To achieve this, the update package must be thoroughly tested and adapted to various hardware configurations and usage environments. At the same time, the update process should be simple and intuitive to reduce the complexity of user operation during updates. Manufacturers should promise to provide system update support for equipment over a certain period to ensure it can adapt to technological developments and changes in user needs, thereby prolonging its service life and improving the durability of mobile telecommunication terminals.
+
+Data security is also an important indicator when evaluating the durability of mobile telecommunication terminals. Proper data security mechanisms, such as encryption, access control and backup recovery, ensure the confidentiality and integrity of user information over the long term and enhance users' trust in their devices. Even if the device is lost or stolen after data encryption, the data cannot easily be accessed or cracked. At the same time, a convenient data recovery mechanism is provided so that data can be quickly recovered in the event of equipment failure or data loss. The built-in security software monitors and prevents viruses, malware, network attacks and other threats in real time, protecting the device and user data.
+
+#### **8.2.5 Manufacturer operation**
+
+The manufacturer's operations are also an important aspect of evaluating the durability of mobile telecommunication terminals. Manufacturers should establish a comprehensive quality management system that covers every stage, from raw material procurement to production, testing, sales and after-sales, to ensure the durability of their products.
+
+During the procurement stage, suppliers are strictly screened to ensure the materials they provide meet high durability standards. During production, precise manufacturing processes and strict quality testing ensure the consistency and stability of products. During product testing, various actual use scenarios are simulated, and comprehensive mechanical stress and environmental adaptability tests are conducted, such as drop, impact, collision, scratch, waterproof and dustproof tests. This allows problems to be identified and improved in a timely manner.
+
+During the sales phase, manufacturers should provide detailed product usage instructions and maintenance guides to help users correctly use and maintain the products.
+
+An after-sales service involves establishing an efficient maintenance and replacement mechanism, responding to user needs in a timely manner, solving problems arising from product use and collecting user feedback to continuously improve and optimize the product.
+
+## **9 Durability assessment indicator of mobile telecommunication terminals**
+
+## **9.1 Evaluation indicator**
+
+The evaluation indicators for mobile telecommunication terminals include environmental applicability, maintenance and repair of the entire device and its accessories, recycling and reuse, system management, data security and manufacturer operation. As shown in Table 2, each type of secondary indicator is divided into four levels: I, II, III and IV. The number of points awarded for meeting each grade level is as follows: 10 points for level I, 8 points for level II, 6 points for level III, and 0 points for level IV.
+
+**Table 2 – Durability assessment indicator requirements of mobile telecommunication terminals**
+
+| Primary indicator          | Secondary indicator                 | Defining the criteria for the indicator                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          | Level assessment (I–IV)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
+|----------------------------|-------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Environmental adaptability | Nonmechanical and mechanical stress | <p><b>Examples of standards which can be considered</b> (to be assessed depending on the type of equipment and the environment in which the product is intended to be used):</p> <ul style="list-style-type: none"> <li>• [b-ETSI EN 300019-x-y series]; for environmental requirements (temperature, humidity, rain, mechanical, etc);</li> <li>• [b-IEC 60068-X series] for environmental requirements (temperature, humidity, rain, mechanical, etc requirements);</li> <li>• [b-ETSI ES 201 468] or [b-ITU-T K.21] and [b-ITU-T K.45] for nonmechanical and stress to electromagnetic voltage transients;</li> <li>• [b-IEC 61960-3] Electrical test acceptance criteria;</li> <li>• Battery protection software.</li> </ul> | <p><b>(I)</b> The product's design features have better characteristics than the minimum requirements for the environmental class in which the product is intended to be used and comply with the enhanced requirements.<br/>(Example: a product intended to be used in non-weather protected location and satisfies the requirements of class 4.1E (extended severity level) of [b-EN 300019-1-4] instead of class 4.1 (minimum severity level) and complies with the enhanced requirements of [b-ITU-T K.21] and [b-ITU-T K.45])</p> |
+|                            |                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | <p><b>(II)</b> The product's design features characteristics comply with the minimum requirements for the environmental class in which the product is intended to be used.<br/>(Example: a product intended to be used in non-weather protected location and satisfies the requirements of class 4.1 of [b-EN 300 019-1-4] and complies with the basic requirements of [b-ITU-T K.21] and [b-ITU-T K.45])</p>                                                                                                                          |
+|                            |                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | <p><b>(III)</b> The product's design features characteristics comply with most of the minimum requirements for the environmental class in which the product is intended to be used.<br/>(Example: a product intended to be used in a non-weather-protected location that satisfies the requirements of class 4.1 of [b-EN 300 019-1-4] but does not comply with the basic resistibility requirements of [b-ITU-T K.21] and [b-ITU-T K.45])</p>                                                                                         |
+|                            |                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | <p><b>(IV)</b> The product's design features characteristics do not comply with several of the minimum requirements for the environmental class in which the product is intended to be used.<br/>(Example: a product intended to be used in a non-weather-protected location that does not satisfy to the chemical active substances (corrosion)requirements of any class of [b-EN 300019-1-4] and does not comply with the basic resistibility requirements of [b-ITU-T K.21] and [b-ITU-T K.45])</p>                                 |
+|                            |                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | <p><b>(I)</b> Plastic scratch resistance equal or greater than 2H regarding [b-ASTM D3363-05].</p>                                                                                                                                                                                                                                                                                                                                                                                                                                     |
+
+**Table 2 – Durability assessment indicator requirements of mobile telecommunication terminals**
+
+| Primary indicator | Secondary indicator      | Defining the criteria for the indicator                                                                                          | Level assessment (I–IV)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
+|-------------------|--------------------------|----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                   | Scratch resistance       | Resistance of housing parts subject to be scratched.                                                                             | <p><b>(II)</b> Plastic scratch resistance equal or greater than H regarding [b-ASTM D3363-05].</p> <p><b>(III)</b> Plastic scratch resistance equal or greater than HB regarding [b-ASTM D3363-05].</p> <p><b>(IV)</b> Plastic scratch resistance lower or equal than B regarding [b-ASTM D3363-05].</p>                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+|                   | Maintenance support      | Availability of consumables, wear-out parts expected to be replaced periodically.<br>Availability of maintenance infrastructure. | <p><b>(I)</b> Consumables and wear-out parts expected to be replaced periodically can be categorized as publicly available (class A in [b-EN 45554]) or as available to independent maintenance service providers (class B in [b-EN 45554]).</p> <p><b>(II)</b> Consumables and wear-out parts expected to be replaced periodically can be categorized as available to manufacturer-authorized maintenance service providers (class C in [b-EN 45554]).</p> <p><b>(III)</b> Consumables and wear-out parts expected to be replaced periodically can be categorized as available to the manufacturer only (class D in [b-EN 45554]).</p> <p><b>(IV)</b> Consumables and wear-out parts expected to be replaced periodically can be categorized as not available (class E in [b-EN 45554]).</p> |
+|                   | Battery service life     | Battery longevity for portable ICT goods.<br>[b-IEC 62620] may be applicable to measure capacity.                                | <p><b>(I)</b> For Li: Battery pack is chargeable to &gt; 80% of its original design capacity after 300 cycles.</p> <p><b>(II)</b> For Li: Battery pack is chargeable to &gt; 70% of its original design capacity after 300 cycles.</p> <p><b>(III)</b> For Li: Battery pack is chargeable to &gt; 60% of its original design capacity after 300 cycles.</p> <p><b>(IV)</b> For Li: Battery pack is chargeable to &lt; 60% of its original design capacity after 300 cycles.</p>                                                                                                                                                                                                                                                                                                               |
+|                   | Spare parts availability | Duration of spare parts availability                                                                                             | <p><b>(I)</b> Spare parts availability can be categorized as long-term (class A, i.e., a repair, reuse or upgrade process, for which the required spare part(s) is/are available for a duration of time that reflects the expected durability of the product category, cf. [b-EN 45554]).</p> <p><b>(II)</b> Spare parts availability can be categorized as mid-term (class B i.e., repair, reuse or upgrade process, for which the required spare part(s) is/are available for a duration of time that reflects the expected average durability of the product, cf. [b-EN 45554]).</p> <p>NOTE – Expected average durability (EAD) is lower than expected durability (ED) as EAD takes into</p>                                                                                              |
+
+Maintenance and repair of the entire machine and accessories
+
+**Table 2 – Durability assessment indicator requirements of mobile telecommunication terminals**
+
+| Primary indicator   | Secondary indicator      | Defining the criteria for the indicator                                                                                                                                            | Level assessment (I–IV)                                                                                                                                                                                                                                                                                                                                                                                                                                               |
+|---------------------|--------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                     |                          |                                                                                                                                                                                    | account the failure rate and warrant returns while ED refers to the duration of the product (the time a customer (the user of the ICT good) can expect the product to last).                                                                                                                                                                                                                                                                                          |
+|                     |                          |                                                                                                                                                                                    | (III) Spare parts availability can be categorized as short-term (class C, i.e., repair, reuse or upgrade process, for which any required spare part is available during a period of two years after the time of sale of the product, cf. [b-EN 45554]).                                                                                                                                                                                                               |
+|                     |                          |                                                                                                                                                                                    | (IV) No information on duration of availability is provided for spare parts (class D, i.e., repair, reuse or upgrade process, for which any required spare part is available at the time of sale, but for which the duration of availability cannot be determined, cf. [b-EN 45554]).                                                                                                                                                                                 |
+| Recycling and reuse | Fasteners and connectors | Fasteners, connectors and tools used to disassemble parts that are likely to need replacement during the expected lifetime of the product are reusable/removable per [b-EN 45554]. | (I) Fasteners and connectors can be categorized as reusable (class A, i.e., an original fastening system that can be completely re-used, or any elements of the fastening system that cannot be re-used are supplied with the new part for a repair, reuse or upgrade process, cf. [b-EN 45554]) and using no tools, basic tools or product specific tools (classes A-C as defined in [b-EN 45554]).                                                                  |
+|                     |                          |                                                                                                                                                                                    | (II) Fasteners and connectors can be categorized as removable (class B, i.e., an original fastening system that is not reusable, but can be removed without causing damage or leaving residue which precludes reassembly (in case of repair or upgrade) or reuse of the removed part (in case of reuse) for a repair, reuse or upgrade process, cf. [b-EN 45554]) and using no tools, basic tools or product specific tools (classes A-C as defined in [b-EN 45554]). |
+|                     |                          |                                                                                                                                                                                    | (III) Fasteners and connectors can be categorized as removable or reusable using proprietary tools.                                                                                                                                                                                                                                                                                                                                                                   |
+|                     |                          |                                                                                                                                                                                    | (IV) Fasteners and connectors can be categorized as neither removable nor reusable (class C, i.e., an original fastening system which is neither removable nor reusable, as defined as in the first two items, for a repair, reuse or upgrade process, cf. [b-EN 45554]).                                                                                                                                                                                             |
+|                     | Disassembly information  | Classification of information availability by comprehensiveness                                                                                                                    | (I) Information is publicly available (class A, i.e., repair, reuse or upgrade process, for which the relevant information is available to all interested parties, cf. [b-EN 45554]).                                                                                                                                                                                                                                                                                 |
+
+**Table 2 – Durability assessment indicator requirements of mobile telecommunication terminals**
+
+| Primary indicator                   | Secondary indicator       | Defining the criteria for the indicator                                                                                                       | Level assessment (I–IV)                                                                                                                                                                                                                                                                                  |
+|-------------------------------------|---------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| System management and data security |                           |                                                                                                                                               | (II) Information is available to independent repair service providers (class B, i.e., repair, reuse or upgrade process for which the relevant information is available to any self-employed professional, as well as any legally established organization, providing repair services, cf. [b-EN 45554]). |
+|                                     |                           |                                                                                                                                               | (III) Information is available to manufacturer-authorized repair service providers (class C, i.e., repair, reuse or upgrade process, for which the relevant information is available to service providers authorized by the product manufacturer to offer repair services, cf. [b-EN 45554]).            |
+|                                     |                           |                                                                                                                                               | (IV) Information is available to the manufacturer only (class D, i.e., repair, reuse or upgrade process, for which the relevant information is available to the product manufacturer, cf. [b-EN 45554]).                                                                                                 |
+|                                     | Software and data support | Availability of software and firmware updates and upgrades                                                                                    | (I) Software and firmware updates and upgrades availability can be categorized as long-term (class A, i.e., for a duration of time that reflects the expected maximum useful life of the product, cf. [b-EN 45554]).                                                                                     |
+|                                     |                           |                                                                                                                                               | (II) Software and firmware updates and upgrades availability can be categorized as mid-term (class B, i.e., for a duration of time that reflects the expected average useful life of the product, cf. [b-EN 45554]).                                                                                     |
+|                                     |                           |                                                                                                                                               | (III) Software and firmware updates and upgrades availability can be categorized as short-term availability (class C, i.e., available during a period of two years after the time of sale of the product, cf. [b-EN 45554]).                                                                             |
+|                                     |                           |                                                                                                                                               | (IV) No information on duration of availability (class D, cf. [b-EN45554]) is provided on software and firmware updates and upgrades availability.                                                                                                                                                       |
+|                                     | Data security             | <b>Data management:</b><br>Personal data to be deleted without compromising the functionality of the device.<br>NOTE – The classification can | (I) Personal data can be erased and the password can be reset by the user. Features are built-in and easily accessible.                                                                                                                                                                                  |
+|                                     |                           |                                                                                                                                               | (II) Personal data can be erased, or the password can be reset with external software, freely available solutions.                                                                                                                                                                                       |
+|                                     |                           |                                                                                                                                               | (III) Erasure of personal data and password reset is possible on request using services of the manufacturer.                                                                                                                                                                                             |
+
+**Table 2 – Durability assessment indicator requirements of mobile telecommunication terminals**
+
+| Primary indicator      | Secondary indicator             | Defining the criteria for the indicator           | Level assessment (I–IV)                                                                                                                                                                                                                                                                            |
+|------------------------|---------------------------------|---------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+|                        |                                 | be undertaken in alignment with [b-EN 45554]      | (IV) Neither the personal data nor password can be manipulated by the user.                                                                                                                                                                                                                        |
+| Manufacturer operation | Service offered by manufacturer | Duration of repair, reuse, upgrade (RRU) services | (I) RRU service availability can be categorized as long-term (class A, i.e., a RRU, which the manufacturer offers for a duration of time that reflects the ED of the product, cf. [b-EN 45554]).<br>NOTE – ED is the time a customer (the user of the ICT good) can expect the product to last.    |
+|                        |                                 |                                                   | (II) RRU service availability can be categorized as mid-term (class B, i.e., a RRU, which the manufacturer offers for a duration of time that reflects the EAD of the product, cf. [b-EN 45554]).<br>NOTE – EAD includes warranty returns and other early failures and is therefore lower than ED. |
+|                        |                                 |                                                   | (III) RRU service availability can be categorized as short-term (class C, i.e., RRU service, which the manufacturer offers for two years after the time of sale of the product, cf. [b-EN 45554]).                                                                                                 |
+|                        |                                 |                                                   | (IV) No RRU service availability is offered.                                                                                                                                                                                                                                                       |
+
+## 9.2 Level assessment
+
+The results of the durability assessment of mobile telecommunication terminals determine the durability level assessment of the products.
+
+These products are graded A, B or C according to their degree of compliance with the assessment criteria. Table 3 shows the durability grades corresponding to the comprehensive scores.
+
+**Table 3 – Durability level assessment of mobile telecommunication terminals**
+
+| Comprehensive score             | Level assessment |
+|---------------------------------|------------------|
+| $80 \leq \text{score} \leq 100$ | A                |
+| $60 \leq \text{score} < 80$     | B                |
+| $\text{Score} < 60$             | C                |
+
+## 10 Documenting the assessment of durability
+
+The assessment of the durability of mobile telecommunication terminals shall be documented. The need to report topic-related content to the different target audiences needs to be assessed. Special care shall be taken to demonstrate the correlation between the information on the results of the assessment and the input data and assumptions used. Depending on the specific target audience for whom the information will be reported, desired content can be selected correspondingly.
+
+## Bibliography
+
+- [b-ITU-T K.21] Recommendation ITU-T K.21 (2022), *Resistibility of telecommunication equipment installed in customer premises to overvoltages and overcurrents.*
+- [b-ITU-T K.45] Recommendation ITU-T K.45 (2022), *Resistibility of telecommunication equipment installed in the access and trunk networks to overvoltages and overcurrents.*
+- [b-ITU-T L.1022] Recommendation ITU-T L.1022 (2019), *Circular economy: Definitions and concepts for material efficiency for information and communication technology.*
+- [b-ITU-T L.1023] Recommendation ITU-T L.1023 (2023), *Assessment method for circularity performance scoring.*
+- [b-ASTM D3363-05] ASTM D3363-05:2011, *Standard Test Method for Film Hardness by Pencil Test.*
+- [b-EN 45554] EN-45554:2020, *General methods for the assessment of the ability to repair, reuse and upgrade energy-related products.*
+- [b-EN 300 019-1-4] ETSI EN 300 019-1-4:2014, *Environmental Engineering (EE); Environmental conditions and environmental tests for telecommunications equipment; Part 1-4: Classification of environmental conditions; Stationary use at non-weather protected locations.*
+- [b-ETSI EN 300019-x-y series] ETSI EN 300 019 series, *Environmental Engineering (EE); Environmental conditions and environmental tests for telecommunications equipment.*
+- [b-ETSI ES 201 468] ETSI ES 201 468:2000, *Electromagnetic compatibility and Radio spectrum Matters (ERM); Additional ElectroMagnetic Compatibility (EMC) requirements for telecommunications equipment for enhanced availability of service in specific applications.*
+- [b-IEC 60068-1] IEC 60068-1:2013, *Environmental testing-part 1: general and guidance.*
+- [b-IEC 60068-X series] IEC 60068-X series, *Environmental testing.*
+- [b-IEC 60300-3-5] IEC 60300-3-5:2021, *Dependability management – Part 3-5: Application guide – Reliability test conditions and statistical test principles.*
+- [b-IEC 60605-4] IEC 60605-4:2001, *Equipment reliability testing – Part 4: Statistical procedures for exponential distribution – Point estimates, confidence intervals, prediction intervals and tolerance intervals.*
+- [b-IEC 61709] IEC 61709:2017, *Electric components – Reliability – Reference conditions for failure rates and stress models for conversion.*
+
+|                 |                                                                                                                                                                                                                                                                       |
+|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [b-IEC 61960-3] | IEC 61960-3:2017, <i>Secondary cells and batteries containing alkaline or other non-acid electrolytes – Secondary lithium cells and batteries for portable applications – Part 3: Prismatic and cylindrical lithium secondary cells and batteries made from them.</i> |
+| [b-IEC 62620]   | IEC 62620:2014, <i>Secondary cells and batteries containing alkaline or other non-acid electrolytes – Secondary lithium cells and batteries for use in industrial applications.</i>                                                                                   |
+| [b-ISO 14040]   | ISO 14040:2006, <i>Environmental management – Life cycle assessment – Principles and framework.</i>                                                                                                                                                                   |
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|          |                                                                                                                                                                  |
+|----------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A | Organization of the work of ITU-T                                                                                                                                |
+| Series D | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F | Non-telephone telecommunication services                                                                                                                         |
+| Series G | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H | Audiovisual and multimedia systems                                                                                                                               |
+| Series I | Integrated services digital network                                                                                                                              |
+| Series J | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K | Protection against interference                                                                                                                                  |
+| Series L | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O | Specifications of measuring equipment                                                                                                                            |
+| Series P | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R | Telegraph transmission                                                                                                                                           |
+| Series S | Telegraph services terminal equipment                                                                                                                            |
+| Series T | Terminals for telematic services                                                                                                                                 |
+| Series U | Telegraph switching                                                                                                                                              |
+| Series V | Data communication over the telephone network                                                                                                                    |
+| Series X | Data networks, open system communications and security                                                                                                           |
+| Series Y | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z | Languages and general software aspects for telecommunication systems                                                                                             |

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+
+
+# Recommendation **ITU-T L.1027 (08/2023)**
+
+SERIES L: Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant
+
+E-waste and circular economy
+
+### **Assessment of material efficiency of ICT network infrastructure goods (circular economy) – Server and data storage product disassembly and disassembly instruction**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features the letters "ITU" in a bold, blue, sans-serif font, superimposed on a stylized globe with latitude and longitude lines.
+
+ITU logo
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+### **Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant**
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| OPTICAL FIBRE CABLES                                   | L.100-L.199          |
+| Cable structure and characteristics                    | L.100-L.124          |
+| Cable evaluation                                       | L.125-L.149          |
+| Guidance and installation technique                    | L.150-L.199          |
+| OPTICAL INFRASTRUCTURES                                | L.200-L.299          |
+| Infrastructure including node elements (except cables) | L.200-L.249          |
+| General aspects and network design                     | L.250-L.299          |
+| MAINTENANCE AND OPERATION                              | L.300-L.399          |
+| Optical fibre cable maintenance                        | L.300-L.329          |
+| Infrastructure maintenance                             | L.330-L.349          |
+| Operation support and infrastructure management        | L.350-L.379          |
+| Disaster management                                    | L.380-L.399          |
+| PASSIVE OPTICAL DEVICES                                | L.400-L.429          |
+| MARINIZED TERRESTRIAL CABLES                           | L.430-L.449          |
+| <b>E-WASTE AND CIRCULAR ECONOMY</b>                    | <b>L.1000-L.1199</b> |
+| POWER FEEDING AND ENERGY STORAGE                       | L.1200-L.1299        |
+| ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES | L.1300-L.1399        |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES  | L.1400-L.1499        |
+| ADAPTATION TO CLIMATE CHANGE                           | L.1500-L.1599        |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES        | L.1600-L.1699        |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                    | L.1700-L.1799        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.1027
+
+## Assessment of material efficiency of ICT network infrastructure goods (circular economy) – Server and data storage product disassembly and disassembly instruction
+
+## Summary
+
+Recommendation ITU-T L.1027 contains methods to assess the ability to disassemble certain key components of servers and data storage products, and the provision of information on these disassembly operations. It places a special emphasis on aspects relevant to the circular economy, such as fostering durability and reparability, in particular by third parties.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T L.1027   | 2023-08-13 | 5           | 11.1002/1000/15597 |
+
+## Keywords
+
+Circular economy, data storage product, disassembly, environment, E-waste management, KPI, server, waste management.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                                        | Page |
+|------------------------------------------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                                                          | 1    |
+| 2 References.....                                                                                                      | 1    |
+| 3 Definitions .....                                                                                                    | 2    |
+| 3.1 Terms defined elsewhere .....                                                                                      | 2    |
+| 3.2 Terms defined in this Recommendation.....                                                                          | 3    |
+| 4 Abbreviations and acronyms .....                                                                                     | 3    |
+| 5 Conventions .....                                                                                                    | 3    |
+| 6 Assessment of ability to disassemble .....                                                                           | 3    |
+| 6.1 Scope of the assessment .....                                                                                      | 3    |
+| 6.2 Provision of instructions on disassembly operations.....                                                           | 4    |
+| 6.3 Ensuring joining, fastening and sealing techniques do not prevent<br>disassembly for repair or reuse purposes..... | 5    |
+| Appendix I – Identified considerations for servers and storage products.....                                           | 7    |
+| I.1 Scope .....                                                                                                        | 7    |
+| I.2 Futureproofness and next-level subassembly .....                                                                   | 7    |
+| I.3 Traceability.....                                                                                                  | 8    |
+| I.4 Registration of repairers .....                                                                                    | 8    |
+| I.5 Exemptions .....                                                                                                   | 9    |
+| Bibliography.....                                                                                                      | 10   |
+
+## Introduction
+
+This Recommendation contains methods to assess the ability to disassemble certain key components of servers and data storage products, and the provision of information on these disassembly operations. This Recommendation places a special emphasis on aspects relevant to the circular economy, such as fostering durability and reparability, in particular by third parties (such as spare parts repairers and maintenance).
+
+The present document was developed jointly by ETSI TC EE and ITU-T Study Group 5. It is published respectively by ITU and ETSI as Recommendation ITU-T L.1027 and [b-ETSI EN 303 800-5], which are technically equivalent.
+
+## Recommendation ITU-T L.1027
+
+## Assessment of material efficiency of ICT network infrastructure goods (circular economy) – Server and data storage product disassembly and disassembly instruction
+
+## 1 Scope
+
+This Recommendation specifies methods to measure the ability of the following products to be disassembled:
+
+- 1) Servers;
+- 2) Data storage equipment.
+
+The Recommendation covers demonstration of compliance with the following requirements of EU Regulation 2019/424:
+
+- i) The ability to disassemble, with particular regard to assessing that joining, fastening or sealing techniques do not prevent disassembly for repair or reuse purposes.
+- ii) The provision of instructions on disassembly operations, including the type of operation, the type and number of fastening technique(s) to be unlocked and the tool(s) required.
+
+The following products are out of scope of this Recommendation:
+
+- Servers that are used in means of transport for persons or goods;
+- Servers intended for embedded applications;
+- Servers classified as small scale servers in terms of [b-EC 617/2013];
+- Servers with more than four processor sockets;
+- Server appliances;
+- Large servers;
+- Fully fault tolerant servers;
+- Network servers;
+- Small data storage products;
+- Large data storage products.
+
+The decision whether a product should be repaired, reused or upgraded is out of scope. This is dependent on a range of factors including various environmental aspects and other relevant considerations, such as safety and health, technical requirements for functionality, quality and the performance of the server or storage product.
+
+NOTE – See Directive [b-2009/125/EC].
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 battery** [b-EU 2023/1542]: Any source of electrical energy generated by direct conversion of chemical energy and consisting of one or more non-rechargeable or rechargeable battery cells or of groups of them.
+
+**3.1.2 blade chassis** [b-EU 2019/424]: Enclosure that contains shared resources for the operation of blade servers, blade storage, and other blade form-factor devices.
+
+**3.1.3 data storage product** [b-EU 2019/424]: Fully-functional storage system that supplies data storage services to clients and devices attached directly or through a network.
+
+NOTE – Parts and subsystems that are an integral part of the data storage product architecture (e.g., to provide internal communications between controllers and disks) are considered to be part of the data storage product. In contrast, parts that are normally associated with a storage environment at the data centre level (e.g., devices required for operation of an external storage area network) are not considered to be part of the data storage product. A data storage product may be composed of integrated storage controllers, data storage devices, embedded network elements, software, and other devices.
+
+**3.1.4 data storage device** [b-EU 2019/424]: Device providing non-volatile data storage, with the exception of aggregating storage elements such as subsystems of redundant arrays of independent disks, robotic tape libraries, filers, and file servers and storage devices which are not directly accessible by end-user application programs, and are instead employed as a form of internal cache.
+
+**3.1.5 disassembly** [b-EU 2019/424] [b-EN 45550]: Process whereby an item is taken apart in such a way that it can subsequently be reassembled and made operational.
+
+**3.1.6 expansion card** [b-EU 2019/424]: Internal component connected by an edge connection over a common/standard interface such as Peripheral Component Interconnect Express providing additional functionality.
+
+**3.1.7 graphics card** [b-EU 2019/424]: Expansion card containing one or more graphics processing units with a local memory controller interface and local graphics-specific memory.
+
+**3.1.8 manufacturer** [b-EC 2016/C 272/01]: Any natural or legal person who manufactures a product or has a product designed or manufactured, and places it on the market under his own name or trademark.
+
+**3.1.9 memory** [b-EU 2021/341]: Part of a server or a data storage product external to the processor in which information is stored for immediate use by the processor, expressed in gigabyte (GB).
+
+**3.1.10 motherboard** [b-EU 2021/341]: Main circuit board of a server or a data storage product. The motherboard includes connectors for attaching additional boards and typically includes the following components: processor, memory, BIOS, and expansion slots.
+
+**3.1.11 part** [b-EN 45447]: Hardware, firmware or software constituent of a product.
+
+NOTE – Firmware and software are not relevant for the purpose of this Recommendation.
+
+**3.1.12 power supply unit (PSU)** [b-EU 2019/424]: Device that converts Alternate Current (AC) or Direct Current (DC) input power to one or more DC power outputs for the purpose of powering a server or a data storage product.
+
+**3.1.13 processor** [b-EU 2021/341]: Logic circuitry that responds to and processes the basic instructions that drive a server or a data storage product.
+
+NOTE 1 – The processor is the CPU of the server. A typical CPU is a physical package to be installed on the server motherboard via a socket or direct solder attachment. The CPU package may include one or more processor cores.
+
+NOTE 2 – For some soldered processors to function properly after reassembly, the tools used and skills of the disassembly personnel need to be of the highest class level.
+
+**3.1.14 server** [b-EU 2019/424]: Computing product that provides services and manages networked resources for client devices, such as desktop computers, notebook computers, desktop thin clients, internet protocol telephones, smartphones, tablets, tele-communication, automated systems or other servers, primarily accessed via network connections, and not through direct user input devices, such as a keyboard or a mouse and with the following characteristics:
+
+- a) it is designed to support server operating systems (OS) and/or hypervisors, and targeted to run user-installed enterprise applications;
+- b) it supports error-correcting code and/or buffered memory (including both buffered dual inline memory modules and buffered on board configurations);
+- c) all processors have access to shared system memory and are independently visible to a single OS or hypervisor.
+
+### **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following term:
+
+**3.2.1 next-level subassembly:** Subassembly comprising up to three of the key parts b) to d) listed in clause 6.1.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                            |
+|------|----------------------------|
+| AC   | Alternate Current          |
+| ATEX | Atmosphere Explosible      |
+| BIOS | Basic Input Output Systems |
+| CPU  | Central Processing Unit    |
+| DC   | Direct Current             |
+| OS   | Operating System           |
+| PSU  | Power Supply Unit          |
+| SoC  | Systems on Chip            |
+
+## **5 Conventions**
+
+None.
+
+## **6 Assessment of ability to disassemble**
+
+### **6.1 Scope of the assessment**
+
+The core intent of this Recommendation is to demonstrate the ability to disassemble based on criteria it lays down. The disassembly is limited to the following key parts which shall be included in the assessment, when present:
+
+- a) data storage devices;
+- b) memory;
+- c) processor (CPU);
+- d) motherboard;
+
+- e) expansion card/graphic card;
+- f) power supply unit (PSU);
+- g) chassis;
+- h) batteries.
+
+It shall be ensured and demonstrated that the server and data storage product can be disassembled to access the above parts irrespective of the joining, sealing and fastening techniques used, for purposes of repair or reuse.
+
+NOTE 1 – See [b-EU 2019/424].
+
+At the product design stage, the ability to disassemble the server and data storage product will take into account the reasonable balance between the various environmental aspects and other relevant considerations, such as safety and health, technical requirements for the functionality, quality and performance of the server or data storage product.
+
+NOTE 2 – See [b-2009/125/EC].
+
+The availability of guideline instructions for disassembly to access the above parts for repair or reuse purposes shall be ensured. (See Table 1 Class B and clause 6.2.)
+
+Furthermore, information availability is subject to registration if requested by the manufacturer, their authorized representatives or importers.
+
+NOTE 3 – See [b-2009/125/EC].
+
+Table 1 classifies to whom the information shall be made available.
+
+**Table 1 – Classification of information availability for servers and data storage products by target groups**
+
+| Category                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  | Class |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|
+| <b>Publicly available:</b> A disassembly process, for which the relevant information is available to all interested parties.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              | A     |
+| <b>Available to independent repair service providers/operators:</b> A disassembly process, for which the relevant information is not publicly available as described above (Class A), but is available to any self-employed professional, as well as any legally established organization, providing repair services.<br>NOTE – This includes third parties dealing with the maintenance, repair, reuse, recycling and upgrading of servers (including brokers, spare parts repairers, spare parts manufacturers, their authorized representatives and importers, recyclers and third party maintenance) upon registration by the interested third party on a website (see clause 6.2.1). | B     |
+
+NOTE – See [b-EN 45554], Table A.11.
+
+### 6.2 Provision of instructions on disassembly operations
+
+#### 6.2.1 Instruction content and availability
+
+The availability of guideline instructions for disassembly to access the parts listed in clause 6.1 for repair or reuse purposes of the products in scope shall be ensured on a free access website of the manufacturer, importer or authorized representative. The instructions shall be made available to third parties dealing with maintenance, repair, reuse, recycling and upgrading of servers (including brokers, spare parts repairers, spare parts providers, recyclers and third party maintenance) upon registration by the interested third party on a website.
+
+The instructions may include:
+
+- a disassembly map or exploded view;
+
+- information on how to access professional repair (internet webpages, addresses, contact details).
+
+NOTE 1 – Installation manuals could serve as purpose for disassembly/assembly instructions.
+
+For each necessary operation and part the instructions shall contain:
+
+- the type of disassembly operation,
+- the type and number of fastening technique(s) to be unlocked,
+- the exact tools needed to unlock any fastening technique as deployed.
+
+NOTE 2 – Visual representation of the procedure to be followed should be added to the instruction to clarify the operation.
+
+These instructions shall be provided upon request to third parties dealing with maintenance, repair, reuse, recycling and upgrading of servers (including brokers, spare parts repairers, spare parts manufacturers, their authorized representatives and importers, recyclers and third party maintenance) upon registration by the interested third party on a website provided.
+
+In the case of servers, if a product model is part of a server product family, the product information shall be reported either for the product model or, alternatively, for the low-end and high-end configurations of the server product family.
+
+### 6.3 Ensuring joining, fastening and sealing techniques do not prevent disassembly for repair or reuse purposes
+
+As shown in Table 2, joining, fastening and sealing techniques can be categorized into four groups.
+
+**Table 2 – Classification of joining, fastening and sealing techniques for servers and data storage products**
+
+| Category                                                                                                                                                                                                                                                                             | Class |
+|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|
+| <b>Reusable technique/system:</b> An original joining, fastening or sealing technique/system that can be completely reused.                                                                                                                                                          | A     |
+| <b>Semi-reusable technique/system:</b> An original joining, fastening or sealing technique/system where elements of the fastening system that need to be replaced are supplied with the new part (specified in clause 6.1) for the repair.                                           | B     |
+| <b>Removable technique:</b> An original joining, fastening or sealing technique/system that cannot be reused, but can be removed without causing damage or leaving residue which precludes reassembly of the product for the repair or reuse operation or reuse of the removed part. | C     |
+| <b>Neither removable nor reusable technique:</b> An original joining, fastening or sealing technique/system which is neither removable nor reusable without causing damage to the removed part or the remaining product that precludes reassembly or reuse of the parts.             | D     |
+
+NOTE – Categories have been expanded from [b-EN 45554], Table A.1. See also Commission Regulation (EU) 2019/424 [b-EU 2019/424].
+
+Joining, fastening or sealing techniques involved in the disassembly/assembly of the parts in scope of this assessment (clause 6.1) shall be either reusable, semi-reusable or removable in order not to prevent the disassembly for repair or reuse purposes of the parts.
+
+As shown in Table 3, the tools necessary for disassembly can be categorized into four groups.
+
+**Table 3 – Classification of tools for servers and data storage products**
+
+| Category                                                                                                                                                                                                                                                                                                                        | Class |
+|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------|
+| <b>Feasible with basic tools:</b> A disassembly process which can be carried out without the use of any tools, or with a tool or set of tools that is supplied with the product or spare part, or with basic tools as listed in [b-EN 45554], Table A.3.                                                                        | A     |
+| <b>Feasible with other commercially available tools:</b> A disassembly process which cannot be carried out with basic tools as defined above (Class A), but can be carried out without the use of any proprietary tools.                                                                                                        | B     |
+| <b>Feasible with proprietary tools:</b> A disassembly process which can be carried out only with one or more proprietary tools. These are tools that are not available for purchase by the general public or for which any applicable patents are not available to license under fair, reasonable and non-discriminatory terms. | C     |
+| <b>Not feasible with any existing tool:</b> A disassembly process which cannot be carried out with any existing tool.                                                                                                                                                                                                           | D     |
+
+## Appendix I
+
+## Identified considerations for servers and storage products
+
+(This appendix does not form an integral part of this Recommendation.)
+
+There are some special considerations which were identified by participants when developing the present Recommendation. These considerations and reflections may be useful for review and preparation of the next standard.
+
+### I.1 Scope
+
+The following servers or data storage products being addressed by other Directives and which have special demands on the reliability of the disassembled products need special consideration when applying this present document:
+
+Those which:
+
+- are subject to Directive 2014/34/EU, Equipment and protective systems intended for use in potentially explosive atmospheres (ATEX) [b-EU 2014/34/EU];
+- are subject to Council Directive [93/42/EEC] Medical Devices [b-EU 93/42/EEC];
+- are subject to Directive 90/385/EEC, Active Implantable Medical Devices [b-EU 90/385/EEC];
+- are subject to Directive 98/79/EC, In Vitro Diagnostic Medical Devices [b-EU 98/79/EC];
+- are subject to Directive 2014/32/EU, Measuring Instruments [b-EU 2014/32/EU].
+
+NOTE – See Commission Regulation (EU) No 617/2013 [b-EC 617/2013].
+
+### I.2 Futureproofness and next-level subassembly
+
+Generally, ecodesign requirements should not affect the functionality or affordability of servers and data storage products from the end-user's perspective and should not negatively affect health, safety or the environment.
+
+The technological development regarding the manner in which the parts in clause 6.1 are assembled is far from static.
+
+Where a part cannot be repaired or reused without:
+
+- a) significant negative impact on the functionality of the product, from the perspective of the user or;
+- b) adverse effects to health, safety and the environment or;
+- c) adversely affecting health, safety or the environment or;
+- d) significant negative impact on consumers in particular as regards the affordability and the life cycle cost of the product;
+
+the manufacturer may either
+
+- a) provide for repair and reuse in an alternative manner than described in this Recommendation.
+
+For example:
+
+Microsystems packaging concepts such as systems-on-chip (SoC) integrate e.g., the memory and the processor in one integrated circuit. SoC disassembly is not practical. Therefore, categorical requirements of disassembly of memories and processors using SoC technology is very challenging.
+
+Seen in the light of this trend, if the part cannot be repaired and reused without the adverse effects listed above, disassembly should allow the repair and reuse of the next-level subassembly the part is affixed to, or in which it is integrated.
+
+The disassembly operations should demonstrate that each key part – or next-level subassembly – can be removed and replaced such that the product can be restored to a normal operating state, including meeting product safety and product quality requirements or where a) is not practical or possible, not provide for the repair. Moreover, remanufacturing and repair of PCBAs may be difficult in practice. Surface mounted resistors, capacitors, etc. may be damaged by the heat required to unsolder processors. The entire motherboard has to be heated to be able to remove the targeted processors.
+
+### **I.3 Traceability**
+
+Traceability of repairers is important for manufacturers.
+
+The product traceability may be ensured including the identity of the repairer as appropriate. The information may be made available from the time a product model is placed on the market until at least eight years after the placing on the market of the last product of a certain product model, free of charge by manufacturers, their authorized representatives and importers.
+
+After repair or refurbish a product may
+
+- a) be a new product, in which case a natural or legal person different from the original manufacturer becomes the manufacturer with the corresponding obligations;
+- b) not be a new product, in which case the original manufacturer remains the manufacturer. The manufacturer should be permitted means to able to confirm the repair process and materials are sufficient to ensure the product continues to meet compliance requirements.
+
+For these reasons, traceability of repairers is important for manufacturers.
+
+### **I.4 Registration of repairers**
+
+In the case of Class B (Table 1) information availability by target group, manufacturers – or their authorized representatives and importers – may request the third party to qualify that it is dealing with maintenance, repair, reuse, recycling and upgrading of servers.
+
+The manufacturer's, importer's or authorized representative's website may indicate the process for professional repairers to register for access to information.
+
+To accept such a request, the manufacturers, importers or authorized representatives may require the professional repairer to demonstrate that:
+
+- i) The professional repairer has the technical competence to repair servers and data storage products and complies with the applicable regulations for repairers of electrical equipment in the Member States where it operates. Reference to an official registration system as professional repairer, where such system exists in the Member States concerned, should be accepted as proof of compliance with this point;
+- ii) The professional repairer is covered by insurance covering liabilities resulting from its activity regardless of whether this is required by the Member State.
+
+The registration to access the website may contain confidentiality clauses.
+
+Manufacturers – or their authorized representatives and importers – are able to reject an application based e.g., on the following conditions:
+
+- If the third party is on the counterfeit watchlist, or if the third party is located in a country under embargo or if the third party has been convicted of counterfeiting in the past.
+- If the third party is a direct competitor.
+
+The third party rejected need to be informed of the reasons for rejection.
+
+Moreover, manufacturers should not be required to divulge trade secrets.
+
+### **I.5 Exemptions**
+
+During the development of the next Recommendation, the following exemptions may be discussed.
+
+- 1 Joining, fastening and sealing techniques intended to provide for compliance to Directive 2014/35/EU (Low Voltage Directive) [b-EU 2014/35/EU] or Directive 2001/95/EC (General Product Safety Directive) [b-EU 2001/95/EC].
+- 2 Cases in which there would be:
+  - a) Significant negative impact on the functionality of the product, from the perspective of the user;
+  - b) Adverse effect on health, safety and the environment;
+  - c) Significant negative impact on consumers, in particular as regards the affordability and the life cycle cost of the product;
+  - d) Significant negative impact on the industry's competitiveness;
+  - e) The consequence of imposing proprietary technology on manufacturers; and [b-2009/125/EC] (Article 15 Paragraph 5).
+
+The manufacturer – or their authorized representatives and importers – should provide evidence to support exemptions 1 and 2.
+
+## Bibliography
+
+- |                       |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
+|-----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| [b-2009/125/EC]       | Directive 2009/125/EC of the European Parliament and of the Council of 21 October 2009 establishing a framework for the setting of ecodesign requirements for energy-related products (recast).                                                                                                                                                                                                                                                                                                                                                                                                              |
+| [b-EC 2016/C 272/01]  | European Commission Notice 2016/C 272/01 (2016), <i>The 'Blue Guide' on the implementation of EU products rules</i> , p. 28.<br><a href="https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52016XC0726(02)&amp;from=BG">https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:52016XC0726(02)&amp;from=BG</a>                                                                                                                                                                                                                                                                            |
+| [b-EC 617/2013]       | Commission Regulation (EU) No 617/2013 of 26 June 2013 implementing Directive 2009/125/EC of the European Parliament and of the Council with regard to ecodesign requirements for computers and computer servers.                                                                                                                                                                                                                                                                                                                                                                                            |
+| [b-EN 45550]          | CENELEC EN 45550:2020, <i>Definitions related to material efficiency</i> .                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
+| [b-EN 45554]          | CENELEC EN 45554:2020, <i>General method for the assessment of the ability to repair, reuse and upgrade energy-related products</i> .                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
+| [b-ETSI EN 303 800-5] | ETSI EN 303 800-5, <i>Assessment of material efficiency of ICT network infrastructure goods (circular economy) part 5 – server and data storage product disassembly and disassembly instruction</i> .                                                                                                                                                                                                                                                                                                                                                                                                        |
+| [b-EU 2001/95/EC]     | Directive 2001/95/EC of the European Parliament and of the Council of 3 December 2001 on general product safety.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
+| [b-EU 2014/32/EU]     | Directive 2014/32/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of measuring instruments (recast) Text with EEA relevance.                                                                                                                                                                                                                                                                                                                                                       |
+| [b-EU 2014/34/EU]     | Directive 2014/34/EU, <i>Equipment and protective systems intended for use in potentially explosive atmospheres (ATEX)</i> .                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |
+| [b-EU 2014/35/EU]     | Directive 2014/35/EU Directive 2014/35/EU of the European Parliament and of the Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to the making available on the market of electrical equipment designed for use within certain voltage limits.                                                                                                                                                                                                                                                                                                                     |
+| [b-EU 2019/424]       | Commission Regulation (EU) 2019/424 of 15 March 2019 laying down ecodesign requirements for servers and data storage products pursuant to Directive 2009/125/EC of the European Parliament and of the Council and amending Commission Regulation (EU) No 617/2013.                                                                                                                                                                                                                                                                                                                                           |
+| [b-EU 2021/341]       | Commission Regulation (EU) 2021/341 of 23 February 2021 amending Regulations (EU) 2019/424, (EU) 2019/1781, (EU) 2019/2019, (EU) 2019/2020, (EU) 2019/2021, (EU) 2019/2022, (EU) 2019/2023 and (EU) 2019/2024 with regard to ecodesign requirements for servers and data storage products, electric motors and variable speed drives, refrigerating appliances, light sources and separate control gears, electronic displays, household dishwashers, household washing machines and household washer-dryers and refrigerating appliances with a direct sales function (Text with EEA relevance) C/2021/923. |
+
+- [b-EU 2023/1542] Regulation (EU) 2023/1542 of the European Parliament and of the Council of 12 July 2023 concerning batteries and waste batteries, amending Directive 2008/98/EC and Regulation (EU) 2019/1020 and repealing Directive 2006/66/EC.
+- [b-EU 90/385/EEC] Directive 90/385/EEC of 20 June 1990 on the approximation of the laws of the Member States relating to active implantable medical devices.
+- [b-EU 98/79/EC] Directive 98/79/EC of the European Parliament and of the Council of 27 October 1998 on in vitro diagnostic medical devices.
+- [b-EU 93/42/EEC] Council Directive 93/42/EEC of 14 June 1993 concerning medical devices.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

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+
+
+# Recommendation
+
+## **ITU-T L.104 (05/2025)**
+
+SERIES L: Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant
+
+Optical fibre cables – Cable structure and characteristics
+
+---
+
+## **Small count optical fibre cables for indoor applications**
+
+![ITU logo](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+## **Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant**
+
+|                                                        |                    |
+|--------------------------------------------------------|--------------------|
+| OPTICAL FIBRE CABLES                                   | L.100-L.199        |
+| <b>Cable structure and characteristics</b>             | <b>L.100-L.124</b> |
+| Cable evaluation                                       | L.125-L.149        |
+| Guidance and installation technique                    | L.150-L.199        |
+| OPTICAL INFRASTRUCTURES                                | L.200-L.299        |
+| MAINTENANCE AND OPERATION                              | L.300-L.399        |
+| PASSIVE OPTICAL DEVICES                                | L.400-L.429        |
+| MARINIZED TERRESTRIAL CABLES                           | L.430-L.449        |
+| E-WASTE AND CIRCULAR ECONOMY                           | L.1000-L.1199      |
+| POWER FEEDING AND ENERGY STORAGE                       | L.1200-L.1299      |
+| ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES | L.1300-L.1399      |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES  | L.1400-L.1499      |
+| ADAPTATION TO CLIMATE CHANGE                           | L.1500-L.1599      |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES        | L.1600-L.1699      |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                    | L.1700-L.1799      |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.104
+
+## Small count optical fibre cables for indoor applications
+
+## Summary
+
+Recommendation ITU-T L.104 describes the characteristics, construction and test methods of small count optical fibre cables for indoor applications. Indoor optical fibre cables that contain three or more fibres have been described in Recommendation ITU-T L.103/L.59. This Recommendation deals with small count optical fibre cables that contains one or two optical fibre(s). This Recommendation describes the cable characteristics that are required if an optical fibre is to demonstrate sufficient levels of performance. A method is described for determining whether the cable has the required characteristics to support the conditions where it is installed. The conditions may differ according to the installation environment. Therefore, detailed test conditions of experiments should be agreed between a user and a supplier on the basis on the environment in which a cable is to be used. In this revision, the template of Recommendation ITU-T L.104 was updated to be consistent with the latest L-series optical fibre cable Recommendations. ITU-T G.657 fibre was added as an optical fibre which can be used to the small count optical fibre cables for indoor applications. Existing appendices which describe various national experiences have been transferred to the new Supplement for L.100-series Recommendations.
+
+## History \*
+
+| Edition | Recommendation   | Approval   | Study Group | Unique ID          |
+|---------|------------------|------------|-------------|--------------------|
+| 1.0     | ITU-T L.104/L.67 | 2006-10-29 | 6           | 11.1002/1000/8926  |
+| 2.0     | ITU-T L.104      | 2025-05-14 | 15          | 11.1002/1000/16338 |
+
+## Keywords
+
+Cable structure, cable testing, indoor cabling, small count optical fibre cable.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, and information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <https://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2025
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|     |                                                                |    |
+|-----|----------------------------------------------------------------|----|
+| 1   | Scope.....                                                     | 1  |
+| 2   | References.....                                                | 1  |
+| 3   | Definitions .....                                              | 3  |
+| 3.1 | Terms defined elsewhere .....                                  | 3  |
+| 3.2 | Terms defined in this Recommendation.....                      | 3  |
+| 4   | Abbreviations and acronyms .....                               | 3  |
+| 5   | Conventions .....                                              | 3  |
+| 6   | Characteristics of optical fibres and cables .....             | 3  |
+| 6.1 | Optical fibre characteristics .....                            | 3  |
+| 6.2 | Mechanical characteristics.....                                | 4  |
+| 6.3 | Environmental characteristics .....                            | 6  |
+| 6.4 | Fire safety .....                                              | 7  |
+| 6.5 | Electrical characteristics .....                               | 7  |
+| 7   | Cable construction .....                                       | 7  |
+| 7.1 | Fibre coatings .....                                           | 7  |
+| 7.2 | Cable element .....                                            | 8  |
+| 7.3 | Sheath .....                                                   | 10 |
+| 7.4 | Identification of cable.....                                   | 11 |
+|     | Annex A – Test methods.....                                    | 12 |
+| A.1 | Test conditions.....                                           | 14 |
+| A.2 | Test methods for cable elements .....                          | 15 |
+| A.3 | Test methods for mechanical characteristics of the cable ..... | 17 |
+| A.4 | Test methods for environmental characteristics .....           | 19 |
+| A.5 | Test methods for electrical characteristics .....              | 21 |
+| A.6 | Test methods for fire safety .....                             | 21 |
+|     | Bibliography.....                                              | 23 |
+
+
+
+# Recommendation ITU-T L.104
+
+## Small count optical fibre cables for indoor applications
+
+# 1 Scope
+
+This Recommendation:
+
+- refers to small count optical fibre cables to be used for telecommunications networks in buildings and houses;
+- recommends that optical fibre dimensional and transmission characteristics should comply with one or more of [ITU-T G.652], [ITU-T G.657], [IEC 60793-2-50];
+- deals with fundamental considerations related to optical fibre cable from mechanical and environmental points of view;
+- acknowledges that some optical fibre cables may contain metallic elements, for which reference should be made to other L-series Recommendations;
+- recommends that an optical fibre cable should be provided with cable end-sealing and protection during cable delivery and storage, as is common for metallic cables. If splicing components have been factory installed, they should be adequately protected.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [[ITU-T G.650.1](#)] Recommendation ITU-T G.650.1 (2024), *Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable*.
+- [[ITU-T G.650.2](#)] Recommendation ITU-T G.650.2 (2015), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable*.
+- [[ITU-T G.650.3](#)] Recommendation ITU-T G.650.3 (2017), *Test methods for installed single-mode optical fibre cable links*.
+- [[ITU-T G.652](#)] Recommendation ITU-T G.652 (2024), *Characteristics of a single-mode optical fibre and cable*.
+- [[ITU-T G.657](#)] Recommendation ITU-T G.657 (2024), *Characteristics of a bending-loss insensitive single-mode optical fibre and cable*.
+- [[ITU-T L.101](#)] Recommendation ITU-T L.101 (2024), *Optical fibre cables for directly buried application*.
+- [IEC 60304] IEC 60304:1982, *Standard colours for insulation for low-frequency cables and wires*.
+- [IEC 60332-1-1] IEC 60332-1-1:2004, *Tests on electric and optical fibre cables under fire conditions – Part 1-1: Test for vertical flame propagation for a single insulated wire or cable – Apparatus*.
+
+- [IEC 60332-1-2] IEC 60332-1-2:2025, *Tests on electric and optical fibre cables under fire conditions – Part 1-2: Test for vertical flame propagation for a single insulated wire or cable – Procedure for 1 kW pre-mixed flame.*
+- [IEC 60332-3-24] IEC 60332-3-24:2018, *Tests on electric and optical cables under fire conditions – Part 3-24: Test for vertical flame spread of vertically-mounted bunched wires or cables – Category C.*
+- [IEC 60332-3-25] IEC 60332-3-25:2018, *Tests on electric and optical fibre cables under fire conditions – Part 3-25: Test for vertical flame spread of vertically-mounted bunched wires or cables – Category D.*
+- [IEC 60754-1] IEC 60754-1:2011, *Test on gases evolved during combustion of materials from cables – Part 1: Determination of the amount of halogen acid gas.*
+- [IEC 60754-2] IEC 60754-2:2011, *Test on gases evolved during combustion of electric cables – Part 2: Determination of degree of acidity of gases evolved during the combustion of materials taken from electric cables by measuring pH and conductivity.*
+- [IEC 60793-1-32] IEC 60793-1-32:2018, *Optical fibres – Part 1-32: Measurement methods and test procedures – Coating strippability.*
+- [IEC 60793-1-40] IEC 60793-1-40:2024, *Optical fibres – Part 1-40: Attenuation measurement methods.*
+- [IEC 60793-2-50] IEC 60793-2-50:2018, *Optical fibres – Part 2-50: Product specifications – Sectional specification for class B single-mode fibres.*
+- [IEC 60794-1-1] IEC 60794-1-1:2023, *Optical fibre cables – Part 1-1: Generic specification – General.*
+- [IEC 60794-1-2] IEC 60794-1-2:2021, *Optical fibre cables – Part 1-2: Generic specification – Basic optical cable test procedures.*
+- [IEC 60794-1-21] IEC 60794-1-21:2015, *Optical fibre cables – Part 1-21: Generic specification – Basic optical cable test procedures – Mechanical tests methods.*
+- [IEC 60794-1-22] IEC 60794-1-22:2017, *Optical fibre cables – Part 1-22: Generic specification – Basic optical cable test procedures – Environmental test methods.*
+- [IEC 60794-1-23] IEC 60794-1-23:2019, *Optical fibre cables – Part 1-23: Generic specification – Basic optical cable test procedures – Cable element test methods.*
+- [IEC 60794-1-31] IEC 60794-1-31:2021, *Optical fibre cables – Part 1-31: Generic specification – Optical cable elements – Optical fibre ribbon.*
+- [IEC 60794-1-219] IEC 60794-1-219:2021, *Optical fibre cables – Part 1-219: Generic specification – Basic optical cable test procedures – Material compatibility test, method F19.*
+- [IEC 60794-1-403] IEC 60794-1-403:2021, *Optical fibre cables – Part 1-403: Generic specification – Basic optical cable test procedures – Electrical test methods – Electrical continuity test of cable metallic elements, method H3.*
+- [IEC 60794-2] IEC 60794-2:2017, *Optical fibre cables – Part 2: Indoor cables – Sectional specification.*
+- [IEC 60794-2-20] IEC 60794-2-20:2024, *Optical fibre cables – Part 2-20: Indoor cables – Family specification for multi-fibre optical cables.*
+
+- [IEC 60794-3] IEC 60794-3:2022, *Optical fibre cables – Part 3: Outdoor cables – Sectional specification.*
+- [IEC 60811-202] IEC 60811-202:2012, *Electric and optical fibre cables – Test methods for non-metallic materials – Part 202: General tests – Measurement of thickness of non-metallic sheath.*
+- [IEC 60811-203] IEC 60811-203:2012, *Electric and optical fibre cables – Test methods for non-metallic materials – Part 203: General tests – Measurement of overall dimensions.*
+- [IEC 61034-1] IEC 61034-1:2005, *Measurement of smoke density of cables burning under defined conditions – Part 1: Test apparatus.*
+- [IEC 61034-2] IEC 61034-2:2005, *Measurement of smoke density of cables burning under defined conditions – Part 2: Test procedure and requirements.*
+- [IEC 61196-1-313] IEC 61196-1-313:2009, *Coaxial communication cables – Part 1-313: Mechanical test methods – Adhesion of dielectric and sheath.*
+
+# **3 Definitions**
+
+## **3.1 Terms defined elsewhere**
+
+For the purpose of this Recommendation, the definitions given in [ITU-T G.650.1], [ITU-T G.650.2], [ITU-T G.650.3] and [IEC 60794-1-1] apply.
+
+Other terms used, particularly in referencing IEC test procedures and specifications, are per [IEC 60794-1-1] and other IEC specifications specifically referenced.
+
+## **3.2 Terms defined in this Recommendation**
+
+None.
+
+# **4 Abbreviations and acronyms**
+
+None.
+
+# **5 Conventions**
+
+None.
+
+# **6 Characteristics of optical fibres and cables**
+
+## **6.1 Optical fibre characteristics**
+
+The following optical fibre types should be considered for use in cables of this Recommendation, based on agreement between manufacturers and customers. Single-mode optical fibres should be used as described in [ITU-T G.652], [ITU-T G.657] and [IEC 60793-2-50], depending upon users' environmental conditions and technical requirements. The corresponding IEC fibre category designations are shown in Appendix V of [b-ITU-T G Suppl.40].
+
+### **6.1.1 Transmission characteristics**
+
+The typical transmission characteristics for each type of optical fibre are described in their respective Recommendation. Unless specified by the users of this specific Recommendation, those values are applied for a cabled optical fibre.
+
+The maximum point discontinuity at the operating wavelength(s) for fibres should be in accordance with [IEC 60794-1-1].
+
+Mode-field diameter is defined by [ITU-T G.652] and [ITU-T G.657].
+
+### **6.1.2 Fibre microbending loss**
+
+Severe bending of an optical fibre, involving local axial displacement of a few micrometres over short distances caused by localized lateral forces along its length, is called microbending. This may be caused in cabled fibres by manufacturing and installation strains, as well as dimensional variations of cable materials due to temperature changes during operation.
+
+Microbending can cause an increase in optical loss. In order to reduce microbending loss, stresses randomly applied to a fibre along its axis should be minimized during the incorporation of the fibres into the cable, as well as during and after cable installation.
+
+### **6.1.3 Fibre macrobending loss**
+
+Macrobending is the curvature of an optical fibre resulting after cable manufacturing and installation.
+
+Macrobending may cause an increase in optical loss. Optical loss increases if the bending radius is too small. The optical loss caused by macrobending typically increases as the bending radius is reduced.
+
+NOTE – ITU-T G.657 optical fibres are optimized for reduced macrobending loss.
+
+### **6.1.4 Fibre dimensions**
+
+Cladding diameter is defined by [ITU-T G.652] and [ITU-T G.657].
+
+The overall fibre dimensions and related characteristics such as non-circularity and concentricity are important in the performance of cabled fibre and in the splicing and connectorization of fibres. Accordingly, [IEC 60793-2-50] specifies critical values and measurement methods. The range of fibre outer coating diameter should be in accordance with [IEC 60793-2-50].
+
+## **6.2 Mechanical characteristics**
+
+### **6.2.1 Evaluation of mechanical characteristics**
+
+Cable mechanical characteristics should be evaluated using the test methods and requirements of [IEC 60794-2] series, and applicable Recommendations in clause A.3.
+
+If mechanical forces (e.g., expanding, buckling, bending, torsion, crush and kink) are applied, they may affect the performance of a fibre and a cable. This clause describes the relations between typical mechanical forces and cable performance.
+
+### **6.2.2 Tensile strength**
+
+Optical fibre cable is subject to short-term load during manufacture and installation, and may be affected by continuous static loading or cyclic load during operation (e.g., temperature variation). Changes in the tension of the cable due to the variety of factors encountered during the service life of the cable can cause differential movement of the cable components. This effect should be considered in the cable design.
+
+Excessive cable tensile loading may increase optical loss and may cause increased residual strain in the fibre if the cable cannot relax. When a cable is subjected to permanent loading during its operational life, the fibre should not experience strain beyond values that adversely affect fibre reliability (see clause A.3.1). To avoid these issues, the maximum tensile strength determined by the cable construction, especially the design of the strength member, should not be exceeded.
+
+### 6.2.3 Bending
+
+Under the dynamic conditions encountered during installation, optical fibre is subject to strain from both cable tension and bending. The strength elements in the cable and the installation bend diameter must be selected to limit this combined dynamic strain. Routing and storage may result in permanent bends after installation. Any fibre bend radius remaining after cable installation should be large enough to limit the macrobending loss or long-term strain limiting the lifetime of the fibre.
+
+Minimum bending diameter is an important parameter for the physical integrity of the sheath, for fibre strain limitation and for fibre attenuation performance due to macrobending loss. Cables with smaller core structures can be bent to relatively smaller bend diameters than cables with larger core structures.
+
+The standard minimum bending diameters for cables should be declared by the manufacturer. Cable bending diameters are defined as:
+
+- Residual (installed):  $20 \times$  cable outer diameter (OD) or  $30 \times$  cable OD;
+- Loaded condition (during installation):  $40 \times$  cable OD.
+
+For very small cables such as microduct cables, manufacturers may specify a fixed cable minimum bending diameter that is independent of the cable OD. It should also be noted that the minimum bending diameter changes depending on the cable structure, such as the design and configuration of the strength members.
+
+NOTE – Some cable tests and specifications declare bending criteria in terms of radius of the apparatus or sheave. Care should be taken to avoid incorrect testing.
+
+### 6.2.4 Crush
+
+The cable may be subject to crush and impact during both installation and operational life.
+
+Characteristically, a crushing incident involves a relatively short length of the cable. The crushing may be short-term, such as during installation, or may be long-term over the operational life of the cable.
+
+Cable is constructed to isolate the optical fibres from external compressive forces. The construction and dimensions of the cable affect the resistance of the cable to performance degradation due to crushing.
+
+Crushing may damage the physical integrity of the cable or may increase the optical loss (either temporarily or permanently). Excessive stress may lead to fibre fracture.
+
+### 6.2.5 Bending under tension (flexing)
+
+Under the dynamic conditions encountered during installation and operation, a cable may be subject to bending under tension (flexing). The bending under tension test should be performed according to clause A.3.3. After the test, there should be no fibre breakage.
+
+### 6.2.6 Impact
+
+A cable may be subject to impact during both installation and operational life.
+
+Although in either case the impact is a transient event, it still could result in cable performance deformation and affect the cable over its operational life.
+
+Cable is constructed to isolate the optical fibres from external compressive forces. The construction and dimensions of the cable affect the resistance of the cable to performance degradation due to impact.
+
+Impact may damage the physical integrity of the cable or may increase the optical loss (either temporarily or permanently). Excessive stress may lead to fibre fracture.
+
+Characteristically, impact could cause visible cracks, splits, tears or other openings on the surface of the cable jacket.
+
+### **6.2.7 Torsion**
+
+Under the dynamic conditions encountered during installation and operation, a cable may be subject to torsion. This may be under tension during installation and the torsion may remain after the installation is complete. The torsion may be due to coiling of the cable during installation and will often remain over the operational life of the cable. Torsion may result in optical loss of the fibres and/or damage to the sheath including splitting of the sheath. The cable should be sufficiently robust to resist twisting, and its design should accommodate a reasonable number of cable twists per unit length without an increase in optical loss and/or damage to the sheath.
+
+Characteristically, torsion could cause visible cracks, splits, tears or other openings on the surface of the cable jacket.
+
+### **6.2.8 Kinking**
+
+A cable may be subject to kinking during installation.
+
+### **6.2.9 Repeated bending**
+
+A cable may be subject to repeated bending during installation.
+
+### **6.2.10 Coefficient of friction**
+
+A cable may be subject to a coefficient of friction between cables or between the cable and duct during installation.
+
+## **6.3 Environmental characteristics**
+
+### **6.3.1 Evaluation of environmental characteristics**
+
+Cable environmental characteristics should be evaluated using the test methods and requirements of [IEC 60794-2] series, and applicable discussion in clause A.4.
+
+Environmental conditions for indoor cables may not be as severe as those for outdoor cables. However, if environmental conditions are not defined, it is recommended that the same requirements as those for outdoor cables apply.
+
+### **6.3.2 Temperature variations**
+
+During their operational lifetime, cables may be subject to severe temperature variations. In these conditions, the increase of attenuation of the fibres should not exceed the specified limits.
+
+Cable elements can potentially have different thermal expansion coefficients that can cause differing dimensional changes among the cable elements. This can cause attenuation increases of the optical fibres due to microbending or macrobending effects. Therefore, testing of cables at temperature extremes is recommended.
+
+The ranges of temperature variations are shown in Table 1 (those values are described in [IEC 60794-2-20] as codes A and C), unless there is a different agreement between the manufacturer and user.
+
+**Table 1 – Temperature variations of optical fibre cable**
+
+| Grade code | Temperature range (°C)      |                              | Recommended deployment configuration                          |
+|------------|-----------------------------|------------------------------|---------------------------------------------------------------|
+|            | Lower temperature ( $T_A$ ) | Higher temperature ( $T_B$ ) |                                                               |
+| A          | -20                         | +60                          | Vertical installation                                         |
+| C          | 0                           | +50                          | Horizontal installation and cabling between optical equipment |
+
+## 6.4 Fire safety
+
+In buildings and houses, fire safety presents two major issues. Firstly, cables and cable elements should be difficult to burn. In other words, cables and cable elements should have flame-retardant characteristics. Secondly, cables and cable elements should not generate toxic gases and smoke when burning. Requirements for fire performance may differ in each country.
+
+Optical cables for indoor applications should meet regulations on fire safety as adopted in each country or by telecommunication operators. The following should be considered if no fire safety specifications are provided and selected according to the application: [IEC 60332-1-2], [IEC 60332-3-24], [IEC 60332-3-25], [IEC 60754-1], [IEC 60754-2], [IEC 61034-1] and [IEC 61034-2].
+
+## 6.5 Electrical characteristics
+
+### 6.5.1 Electrical continuity
+
+All metallic elements used in the cable should be electrically continuous. The resistivity of the metallic members should be checked if specified. The reference test method is found in [IEC 60794-1-403].
+
+# 7 Cable construction
+
+## 7.1 Fibre coatings
+
+Fibre coatings are protective layers applied to fibre to enhance mechanical strength and protect the fibre from environmental factors.
+
+### 7.1.1 Primary coating
+
+Silica fibre itself has an intrinsically high strength, but its strength is reduced by surface flaws. A protective primary coating is characteristically applied immediately after drawing the fibre to size.
+
+The optical fibre should be proof tested. In order to guarantee long-term reliability under service conditions, the proof-test strain may be specified, taking into account the permissible strain and required lifetime. Agreed norms for fibre strain in testing and service are discussed in clause A.3.1 of [ITU-T L.101].
+
+NOTE 1 – The optical fibres should be proof tested with a strain equivalent to 1% or as agreed. For certain applications, a larger proof-test strain may be necessary.
+
+In order to prepare the fibre for splicing, it should be possible to remove the primary coating without damage to the fibre and without the use of materials or methods considered to be hazardous or dangerous.
+
+The composition of the primary coating, coloured if required, should be considered in relation to any requirements of local light-injection and detection equipment used in conjunction with fibre-joining methods.
+
+NOTE 2 – Further study is required to advise on suitable testing methods for local light-injection and detection.
+
+Primary-coated fibres should comply with the relevant optical fibre specifications in [IEC 60793-2-50] and the relevant ITU-T G.65x-series Recommendations.
+
+### 7.1.2 Fibre buffer (secondary coating)
+
+A secondary coating, termed a buffer, may be applied directly over the fibre primary coating for a variety of reasons. This is not to be confused with a buffer tube, which is discussed in clause 7.2.3.
+
+Buffers may use single or multiple materials. The buffer may be a tight buffer, intimately in contact with the primary coating, or a semitight buffer, in contact with the primary coating but intended for removal without damaging the primary coating.
+
+Both types of fibre buffer, if used, should comply with the requirements given in [IEC 60794-3].
+
+NOTE – When a fibre buffer is used, it may be difficult to use local light-injection and detection equipment associated with fibre-joining methods.
+
+When using a tight or semitight buffer (loosely applied), the following characteristics are required:
+
+- a tight buffer should be easily removable over a length of 10 to 25 mm for fibre splicing;
+- a semitight buffer should be easily removable over a length of 300 to 500 mm for fibre splicing;
+- with a tight buffer, the nominal diameter should be between 300 and 1300 µm, based on an agreement between the user and supplier. The tolerance should be  $\pm 100$  µm;
+- with a semitight buffer, the nominal diameter should be between 300 and 1300 µm, based on an agreement between the user and supplier. The tolerance should be  $\pm 100$  µm.
+
+When using a tight or semitight buffer (loosely applied), the following items should be requested:
+
+- A tight buffer should be easily removable over a length of 15 to 25 mm for fibre splicing;
+- A semitight buffer should be easily removable over a length of 300 to 2000 mm for fibre splicing;
+- With a tight buffer, the nominal diameter should be between 300 and 1000 µm, based on an agreement between the user and supplier. The tolerance should be  $\pm 100$  µm;
+- With a semitight buffer, the nominal diameter should be between 300 and 1300 µm, based on an agreement between the user and supplier. The tolerance should be  $\pm 100$  µm.
+
+### 7.1.3 Fibre identification
+
+Fibre should be easily identified by colour/tracer/marker and/or position within the cable core. If a colouring method is used, the colours should be clearly distinguishable and have good colour permanence properties, also in the presence of other materials, during the lifetime of the cable.
+
+The need for fibre identification extends to the fibre units (ribbons, slots, buffer tubes, bundles, microbundles, etc.). Unit identification may include colours, printed marks, position in the core or other appropriate means.
+
+Guidance may be found in [b-IEC TR 63194].
+
+### 7.1.4 Strippability of coating
+
+The primary and secondary coatings should be easy to remove and should not hinder splicing or fitting of the fibre to optical connectors.
+
+## 7.2 Cable element
+
+The make-up of the cable core – in particular the number of fibres, their method of protection and identification, the location of strength members and metallic wires or pairs, if required – should be clearly defined.
+
+### 7.2.1 Fibre bundle
+
+Grouping of optical fibres into bundled units is a common method of organizing and identifying fibres within cable cores. Such bundles are commonly assembled using spirally-applied threads or tapes, often colour-coded, to assist in fibre identification. Other methods following this intent may be used. Such bundles may reside in buffer tubes (see clause 7.2.4) or other core structures.
+
+### 7.2.2 Fibre ribbon
+
+Optical fibre ribbons should conform to [IEC 60794-1-31].
+
+Optical fibre ribbons consist of optical fibres aligned in a row. Optical fibre ribbons are divided into types, based on the method used to bind optical fibres. Common types are the edge-bonded type, the encapsulated type and the partially-bonded type. These are shown in Figures 1, 2 and 3, respectively.
+
+In the case of the edge-bonded type, optical fibres are bound by adhesive material located between the optical fibres. In the encapsulated type, optical fibres are bound by coating material covering the entire ribbon structure. In either of these basic types, the partially-bonded configuration may be used to accomplish additional flexibility in the transverse direction. This allows the ribbon to be rolled and accommodated in small core structures.
+
+The fibres of optical fibre ribbons in the as-manufactured configuration should be parallel and not crossed. Optical fibre ribbons should be capable of mass splicing. Each ribbon in a cable should be identified by a printed legend or unique colour (see also clause 7.1.3).
+
+![Cross-section of a typical edge-bonded ribbon](0a5acc4b370bb711096e04f25b8b3feb_img.jpg)
+
+The diagram shows two possible cross-sectional views of an edge-bonded ribbon. Each view consists of four circular optical fibres arranged in a horizontal row. The fibres are separated by small gaps, and the entire row is flanked by two solid black vertical bars on the left and right, representing the adhesive material used for bonding. The word "or" is placed between the two views. A label "L.104(25)" is located below the right-hand view.
+
+Cross-section of a typical edge-bonded ribbon
+
+Figure 1 – Cross-section of a typical edge-bonded ribbon
+
+![Cross-section of a typical encapsulated ribbon](349cffebeefaae56d9034d3fe65bf7c6_img.jpg)
+
+The diagram shows a cross-sectional view of an encapsulated ribbon. It consists of four circular optical fibres arranged in a horizontal row, all contained within a single, solid black rectangular coating. A label "L.104(25)" is located below the diagram.
+
+Cross-section of a typical encapsulated ribbon
+
+Figure 2 – Cross-section of a typical encapsulated ribbon
+
+![Example of a typical partially-bonded ribbon](ded1520e45c0c3e4c46c58984602bf0e_img.jpg)
+
+The diagram shows a perspective view of a partially-bonded ribbon. It consists of four optical fibres, each shown as a long cylinder. The fibres are parallel to each other. Arrows labeled "Not bonded" point to the top surfaces of the fibres, indicating they are not bonded to each other. Arrows labeled "Bonded" point to the side surfaces of the fibres, indicating they are bonded to the adjacent fibres. A label "L.104(25)" is located below the diagram.
+
+Example of a typical partially-bonded ribbon
+
+Figure 3 – Example of a typical partially-bonded ribbon
+
+### 7.2.3 Tube (buffer tube)
+
+A tube construction, commonly called a buffer tube or loose tube, is frequently used for protecting and gathering optical fibres, fibre bundles and/or fibre ribbons. The essential feature of the tube is to provide sufficient space inside the tube to isolate fibres, fibre bundles or ribbons from external stress.
+
+The tubes are commonly made of polymer materials. Cable designs incorporating loose tubes are the most widely deployed, offering an optimized package for handling and robustness. The tubes may be stranded around the other tubes or the central strength member. Such core structures minimize strain and mid-span access may be easier if the SZ method is utilized. Central tube designs may also be used. Water-blocking material may be contained in the tube, if required.
+
+### 7.2.4 Ruggedized fibre
+
+When required for particular applications, further protection for a buffered fibre (see clause 7.1.2) may be provided by surrounding one or more such fibres with an assembly of strength elements, typically non-metallic, and an appropriate jacket material. Such assemblies are small in size and typically reside in the cable core. Such ruggedization may be appropriate for break-out/fan-out cable constructions.
+
+![Figure 4 shows two examples of ruggedized fibre structure. The left diagram shows a single fibre assembly consisting of a central green 'Buffered fibre', surrounded by a white 'Aramid yarn' layer, and an outer blue 'Sheath'. The right diagram shows two such assemblies joined together, forming a figure-eight shape. Labels point to the 'Buffered fibre', 'Aramid yarn', and 'Sheath' in both diagrams. The text 'L.104(25)' is visible below the right diagram.](a4d009d5dd6a4d83759d6d6538188e23_img.jpg)
+
+The image contains two diagrams of ruggedized fibre structures. The left diagram shows a single circular cross-section. At the center is a small green circle labeled 'Buffered fibre'. This is surrounded by a white ring labeled 'Aramid yarn', which is in turn surrounded by an outer blue ring labeled 'Sheath'. The right diagram shows two such circular assemblies joined side-by-side, sharing a common boundary between their blue sheaths. Each assembly has its own central green 'Buffered fibre', white 'Aramid yarn' layer, and blue 'Sheath'. Labels with leader lines point to these components in both diagrams. Below the right diagram, the text 'L.104(25)' is present.
+
+Figure 4 shows two examples of ruggedized fibre structure. The left diagram shows a single fibre assembly consisting of a central green 'Buffered fibre', surrounded by a white 'Aramid yarn' layer, and an outer blue 'Sheath'. The right diagram shows two such assemblies joined together, forming a figure-eight shape. Labels point to the 'Buffered fibre', 'Aramid yarn', and 'Sheath' in both diagrams. The text 'L.104(25)' is visible below the right diagram.
+
+**Figure 4 – Examples of ruggedized fibre structure**
+
+### 7.2.5 Strength member
+
+Strength members mainly serve to limit tensile strain but may also serve to limit compressive strain such as that caused by temperature changes. The cable should be designed with sufficient strength members to meet installation and service conditions so that fibres themselves are not subject to strain levels in excess of the values (see clause A.3.1) or as agreed upon between customer and manufacturer.
+
+Strength members mainly serve to limit tensile strain but may also serve to limit compressive strain as in temperature changes. The strength members may be located within the core or in the sheath layers, or both. The strength member(s) may be either metallic or non-metallic.
+
+In case of the use of metallic strength members, care should be taken to avoid hydrogen generation effects.
+
+If the cable is required to be installed by pushing into conduits, appropriately rigid strength members may be optionally adopted that are suitable for long distance installation with the resistance to buckling and flexibility for passing through conduit bends.
+
+## 7.3 Sheath
+
+The cable core should be covered with a sheath or sheaths suitable for the relevant environmental and mechanical conditions associated with storage, installation and operation. The sheath may be of a composite construction and may include strength members. The selection of the sheath material to optimize the friction forces between the cable sheath and duct should also be considered.
+
+Consideration should also be given to the amount of hydrogen generated from a metallic moisture barrier.
+
+Selection of sheath material is one of many important issues to be considered in order to satisfy fire safety requirements. Polyethylene is widely used as a cable sheath material; however, it may not be suitable for indoor cables from the viewpoint of fire safety.
+
+If the cable is required to be installed by pushing into conduits, a low friction sheath may optionally be adopted, which has both a low coefficient of friction between cables and conduits or other cables and appropriate cable performance, e.g., with regard to fire safety and ageing.
+
+## **7.4 Identification of cable**
+
+It is recommended that a visual identification of optical fibre cables be provided: this can be done by visibly marking the outer sheath. Marking of cable length should be included in cable marking. For identifying cables, embossing, sintering or imprinting, or hot foil, ink-jet or laser printing can be used by agreement between the user and manufacturer.
+
+# Annex A
+
+## Test methods
+
+(This annex forms an integral part of this Recommendation.)
+
+The tests are described according to the [IEC 60794-2] series and the clauses below should be carried out for indoor fibre cables. The attribute values stated herein should be used to assess conformance in the tests. It is not intended that all tests should be carried out; see [IEC 60794-2] series for guidance. See [IEC 60794-2] regarding the frequency of testing; this should be agreed upon between the manufacturer and customer.
+
+The test methods, performance and test criteria are summarized in Tables A.1 to A.5.
+
+**Table A.1 – Optical fibre and cable elements test conditions**
+
+| Characteristic             | Clause | Test <sup>1</sup> | Value <sup>1, 2, 3</sup>                                | Note                |
+|----------------------------|--------|-------------------|---------------------------------------------------------|---------------------|
+| Attenuation coefficient    | A.1.3  | [IEC 60793-1-40]  | See Note 4                                              |                     |
+| No changes in attenuation  | A.1.3  | –                 | As specified in Note 5                                  | Per [IEC 60794-1-1] |
+| No changes in fibre strain | A.1.3  | As applicable     | As specified in Note 5                                  | Per [IEC 60794-1-1] |
+| Ambient temperature        | A.1.4  | As applicable     | Standard ambient and expanded ambient, see clause A.1.4 | Per [IEC 60794-1-2] |
+| Other temperatures         | A.1.5  | As applicable     | Within $\pm 5$ °C of the specified value                |                     |
+
+NOTE 1 – Tests are IEC unless otherwise specified. Letter/number tests are per [IEC 60794-1-2] series unless otherwise specified.
+
+NOTE 2 – "As agreed" means per agreement between the manufacturer and the customer.
+
+NOTE 3 – Reference to the ITU-T L.104 invoking clause implies criteria not detailed in [IEC 60794-2] series or the test method and is overly complex for this table.
+
+NOTE 4 – Cabled fibre attenuation coefficient is specified in corresponding ITU-T G.65x-series Recommendation.
+
+NOTE 5 – No changes in attenuation/strain are related to test uncertainty per [IEC 60794-1-1].
+
+**Table A.2 – Optical fibre and cable element characteristics**
+
+| Characteristic              | Clause  | Test <sup>1</sup>                         | Value <sup>1, 2, 3</sup> | Note                 |
+|-----------------------------|---------|-------------------------------------------|--------------------------|----------------------|
+| Fibre dimensions            | A.2.1.1 | [IEC 60793-1-21]                          | Per [IEC 60793-2-50]     | Per [IEC 60793-2-50] |
+| Fibre coating strippability | A.2.1.2 | [IEC 60793-1-32]                          | Per [IEC 60794-2] series |                      |
+| Material compatibility      | A.2.1.3 | [IEC 60794-1-219]                         | [IEC 60794-1-219]        |                      |
+| Fibre buffers dimensions    | A.2.3.1 | [IEC 60793-1-21]<br>or<br>[IEC 60811-203] | Per [IEC 60794-2] or DS  |                      |
+| Buffer strippability        | A.2.3.2 | E5C of<br>[IEC 60794-1-21]                | See clause A.2.3.2       |                      |
+| Buffer tube dimensions      | A.2.4.1 | [IEC 60811-202]<br>and<br>[IEC 60811-203] | As agreed                |                      |
+
+**Table A.2 – Optical fibre and cable element characteristics**
+
+| Characteristic                                                                                                                                                       | Clause  | Test <sup>1</sup>                           | Value <sup>1, 2, 3</sup>    | Note |
+|----------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|---------------------------------------------|-----------------------------|------|
+| Tube kink                                                                                                                                                            | A.2.4.2 | G7 of [IEC 60794-1-23]                      | Per [IEC 60794-2] series    |      |
+| <i>Fibre ribbons</i>                                                                                                                                                 |         |                                             |                             |      |
+| Ribbon dimensions                                                                                                                                                    | A.2.5.1 | [IEC 60794-1-31]                            | Table 1 of [IEC 60794-1-31] |      |
+| Fibre separability                                                                                                                                                   | A.2.5.2 | [IEC 60794-1-31]                            | [IEC 60794-1-31]            |      |
+| Ribbon strippability                                                                                                                                                 | A.2.5.3 | [IEC 60794-1-31]<br>and<br>[IEC 60793-1-32] | [IEC 60794-1-31]            |      |
+| NOTE 1 – Tests are IEC unless otherwise specified. Letter/number tests are per [IEC 60794-1-2] series unless otherwise specified.                                    |         |                                             |                             |      |
+| NOTE 2 – "As agreed" means per agreement between the manufacturer and the customer.                                                                                  |         |                                             |                             |      |
+| NOTE 3 – Reference to the ITU-T L.104 invoking clause implies criteria not detailed in [IEC 60794-2] series or the test method and is overly complex for this table. |         |                                             |                             |      |
+
+**Table A.3 – Mechanical characteristics**
+
+| Characteristic                                                                                                                                                    | Clause | Test <sup>1</sup>                     | Value <sup>1, 2, 3, 4</sup>                                         | Note                                                                       |
+|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|---------------------------------------|---------------------------------------------------------------------|----------------------------------------------------------------------------|
+| Tensile strength                                                                                                                                                  | A.3.1  | E1 of [IEC 60794-1-21]                | Per [IEC 60794-2] series                                            |                                                                            |
+| Bending                                                                                                                                                           | A.3.2  | E11 of [IEC 60794-1-21]               | Per [IEC 60794-2] series                                            | E11A or E11B of [IEC 60794-1-21]                                           |
+| Bending under tension                                                                                                                                             | A.3.3  | E18A, Procedure 2 of [IEC 60794-1-21] | Per [IEC 60794-2] series                                            |                                                                            |
+| Repeated bending (flex)                                                                                                                                           | A.3.4  | E6 of [IEC 60794-1-21]                | Per [IEC 60794-2] series<br>No change in attenuation after the test |                                                                            |
+| Crush                                                                                                                                                             | A.3.5  | E3A of [IEC 60794-1-21]               | Per [IEC 60794-2] series                                            | Plate/plate crush                                                          |
+| Impact                                                                                                                                                            | A.3.6  | E4 of [IEC 60794-1-21]                | Per [IEC 60794-2] series                                            |                                                                            |
+| Torsion                                                                                                                                                           | A.3.7  | E7 of [IEC 60794-1-21]                | Per [IEC 60794-2] series                                            |                                                                            |
+| Abrasion, cable print                                                                                                                                             | A.3.8  | E2A, method 2 of [IEC 60794-1-21]     | Per [IEC 60794-2] series                                            | Jacket abrasion not tested                                                 |
+| Cable kinking                                                                                                                                                     | A.3.9  | E10 of [IEC 60794-1-21]               | Per [IEC 60794-2] series                                            |                                                                            |
+| Coefficient of friction                                                                                                                                           | A.3.10 | E30 or E34 of [IEC 60794-1-21]        | As agreed                                                           | E30 and E34 can be applied to round-type and flat-type cables respectively |
+| NOTE 1 – Tests are IEC unless otherwise specified. Letter/number tests are per [IEC 60794-1-2] series unless otherwise specified.                                 |        |                                       |                                                                     |                                                                            |
+| NOTE 2 – "As agreed" means per agreement between the manufacturer and the customer.                                                                               |        |                                       |                                                                     |                                                                            |
+| NOTE 3 – Reference to the ITU-T L.104 invoking clause implies criteria not detailed in [IEC 60794-2] series or the test method and overly complex for this table. |        |                                       |                                                                     |                                                                            |
+| NOTE 4 – The relevant document [IEC 60794-2] series should be referred to by deciding the corresponding cable type.                                               |        |                                       |                                                                     |                                                                            |
+
+**Table A.4 – Environmental characteristics**
+
+| Characteristic         | Clause | Test <sup>1</sup>      | Value <sup>1, 2, 3</sup> | Note                             |
+|------------------------|--------|------------------------|--------------------------|----------------------------------|
+| Temperature cycling    | A.4.1  | F1 of [IEC 60794-1-22] | See clause 6.3.2         |                                  |
+| Nuclear radiation      | A.4.2  | F7 of [IEC 60794-1-22] | See clause A.4.2         | Not usually required             |
+| Cable sheath adherence | A.4.3  | [IEC 61196-1-313]      | See clause A.4.3         | For flooded-armour constructions |
+
+NOTE 1 – Tests are IEC unless otherwise specified. Letter/number tests are per [IEC 60794-1-2] series unless otherwise specified.
+
+NOTE 2 – "As agreed" means per agreement between the manufacturer and the customer.
+
+NOTE 3 – Reference to the ITU-T L.104 invoking clause implies criteria not detailed in [IEC 60794-2] series or the test method and is overly complex for this table.
+
+**Table A.5 – Cable construction**
+
+| Characteristic   | Clause  | Test <sup>1</sup>                   | Value <sup>1, 2, 3</sup>                         | Note |
+|------------------|---------|-------------------------------------|--------------------------------------------------|------|
+| Dimensions       | A.2.6.1 | [IEC 60811-202] and [IEC 60811-203] | As agreed                                        |      |
+| Cable OD         | A.2.6.2 | [IEC 60811-203]                     | Stated by manufacturer, per [IEC 60794-2] series |      |
+| Sheath thickness | A.2.6.3 | [IEC 60811-203]                     | Per [IEC 60794-2] series or as agreed            |      |
+
+NOTE 1 – Tests are IEC unless otherwise specified. Letter/number tests are per [IEC 60794-1-2] series unless otherwise specified.
+
+NOTE 2 – "As agreed" means per agreement between the manufacturer and the customer.
+
+NOTE 3 – Reference to the ITU-T L.104 invoking clause implies criteria not detailed in [IEC 60794-2] series or the test method and is overly complex for this table.
+
+**Table A.6 – Electrical characteristics**
+
+| Characteristic        | Clause | Test <sup>1</sup> | Value <sup>1, 2, 3</sup>    | Note                             |
+|-----------------------|--------|-------------------|-----------------------------|----------------------------------|
+| Electrical continuity | A.5.1  | [IEC 60794-1-403] | As agreed, see clause A.5.1 | For cable with metallic elements |
+
+NOTE 1 – Tests are IEC unless otherwise specified. Letter/number tests are per [IEC 60794-1-2] series unless otherwise specified.
+
+NOTE 2 – "As agreed" means per agreement between the manufacturer and the customer.
+
+NOTE 3 – Reference to the ITU-T L.100 invoking clause implies criteria not detailed in [IEC 60794-3-11] or the test method and which is overly complex for this table.
+
+## A.1 Test conditions
+
+#### A.1.1 Ambient temperatures for cable testing
+
+#### A.1.1 Tensile strength
+
+Testing for criteria involving cable tensile strength should be carried out using the tensile rating of clause 6.2.2.
+
+#### A.1.2 Temperature test values
+
+Testing for criteria involving defined temperature extremes should be considered to be carried out using the temperature ranges. Some tests may specify specific test temperatures different from the standard temperature ranges.
+
+#### A.1.3 Attenuation coefficient and changes (no change and allowable change) in attenuation or strain in cable testing
+
+Unless otherwise specified, testing for attenuation requirements should be carried out at 1550 nm for all single-mode fibres.
+
+Unless otherwise specified, changes in attenuation should be calculated with respect to the attenuation values before the start of the test. In most cases, this measurement should be at ambient temperature (see clause A.1.4).
+
+Unless otherwise specified, for tests with attenuation requirements the attenuation increase or decrease at the completion of the test should be no change.
+
+Unless otherwise specified, the defined values for "no change" should be per [IEC 60794-1-1], which are:
+
+- Single-mode, attenuation change  $\leq 0.05$  dB at 1550 nm;
+- Single-mode, attenuation coefficient change  $\leq 0.05$  dB/km at 1550 nm;
+- All types, no change in fibre strain  $\leq 0.05\%$ .
+
+#### A.1.4 Ambient temperatures for cable testing
+
+The ambient temperatures for cable testing should be according to [IEC 60794-1-2] as shown in Table A.7. All testing should use the expanded ambient criteria unless disallowed by the test procedure or as agreed.
+
+The ambient temperatures for cable testing should be according to [IEC 60794-1-2] as shown in Table A.7. All testing should use the expanded ambient criteria unless disallowed by the test procedure or as agreed.
+
+**Table A.7 – Ambient temperature, relative humidity and atmospheric pressure**
+
+| Condition            | Standard ambient                           | Expanded ambient                            |
+|----------------------|--------------------------------------------|---------------------------------------------|
+| Temperature          | $23^{\circ}\text{C} \pm 5^{\circ}\text{C}$ | $25^{\circ}\text{C} \pm 15^{\circ}\text{C}$ |
+| Relative humidity    | 20% to 70%                                 | 5% to 95%                                   |
+| Atmospheric pressure | Site ambient                               | Site ambient                                |
+
+#### A.1.5 Temperature precision at extremes
+
+The temperature value at test temperatures other than ambient should be within  $\pm 5^{\circ}\text{C}$  of the specified values (see clause 6.3.2 and clause A.1.4).
+
+### A.2 Test methods for cable elements
+
+#### A.2.1 Tests applicable to optical fibres
+
+In this clause, optical fibre test methods for assessing fibres and test methods related to splicing and other joining methods are described. Mechanical and optical characteristics test methods for optical fibres are described in [ITU-T G.650.1] and [ITU-T G.650.2] and in the [IEC 60793-1-xx] fibre test methods series.
+
+##### A.2.1.1 Dimensions
+
+For measuring the primary coating diameter, method [IEC 60793-1-21] should be used.
+
+The measured dimensions for cabled fibre should be per [IEC 60793-2-50] or as agreed between customer and manufacturer.
+
+##### **A.2.1.2 Coating strippability**
+
+For measuring the strippability of primary or secondary fibre coatings, method [IEC 60793-1-32] should be used. The strip force should be in accordance with [IEC 60793-2-50].
+
+##### **A.2.1.3 Compatibility with filling materials**
+
+When fibres come into contact with a filling material used for waterproofing, the stability of the fibre coating and the filling material should be examined by tests after accelerated ageing.
+
+The compatibility of optical fibres and buffers with a filling material should be tested per [IEC 60794-1-219].
+
+Dimensional stability and coating transmissivity should be examined by the test method as agreed between the customer and manufacturer.
+
+#### **A.2.2 Tests applicable to fibre units**
+
+##### **A.2.2.1 Colour coding of fibre**
+
+There is no international standard on fibre colour coding. The fibre colouring should comply with the detail specification, which may reflect national or regional norms. See [b-IEC TR 63194] for guidance.
+
+Colours used should comply with [IEC 60304].
+
+##### **A.2.2.2 Fibre and unit identification**
+
+Fibre and unit identification should also comply with the detail specification, which may reflect national or regional norms. See [b-IEC TR 63194] for guidance.
+
+Colours used should comply with [IEC 60304].
+
+#### **A.2.3 Tests applicable to buffered optical fibres**
+
+##### **A.2.3.1 Dimensions**
+
+The outer diameter of all types of fibre secondary coatings (buffers) should comply with [IEC 60794-3] or with the DS. The diameter tolerance should comply with [IEC 60794-2].
+
+Measurements should be performed using [IEC 60793-1-21] or [IEC 60811-203].
+
+##### **A.2.3.2 Buffer strippability**
+
+Buffers should be strippable in a manner consistent with their intended method of connectorization or splicing.
+
+Buffers should be capable of being stripped using the parameters as shown in Table A.8. Stripping methods and measurements should be performed according to [IEC 60794-1-21] method E5C.
+
+**Table A.8 – Strip lengths and forces for buffer strippability test**
+
+| <b>Buffer type</b>         | <b>Material stripped</b>                    | <b>Strip length</b> | <b>Strip force</b> |
+|----------------------------|---------------------------------------------|---------------------|--------------------|
+| Tight                      | Remove buffer and primary coating as a unit | 15 mm $\pm$ 1.5 mm  | 1.3 N to 13 N      |
+| Semitight                  | Remove buffer, primary coating intact       | 15 mm $\pm$ 1.5 mm  | < 13 N             |
+| Easily-removable semitight | Remove buffer, primary coating intact       | 150 mm              | As agreed          |
+
+#### **A.2.4 Tests applicable to buffer tubes**
+
+##### **A.2.4.1 Dimensions**
+
+Buffer tube dimensions should be as agreed between manufacturer and customer.
+
+For measuring buffer tubes the methods of [IEC 60811-202] and [IEC 60811-203] should be used.
+
+##### **A.2.4.2 Tube kinking**
+
+Tube kinking characteristics and testing should be according to [IEC 60794-2] series.
+
+For measuring the kinking characteristics of tubes, [IEC 60794-1-23] method G7 should be used.
+
+#### **A.2.5 Tests applicable to ribbons**
+
+##### **A.2.5.1 Dimensions**
+
+Fibre ribbon dimensions should be according to [IEC 60794-1-31], Table 1. Ribbon dimensions should be measured according to [IEC 60794-1-31].
+
+##### **A.2.5.2 Separability of individual fibres from a ribbon**
+
+Separability of individual fibres from a ribbon should be according to [IEC 60794-1-31].
+
+##### **A.2.5.3 Strippability**
+
+Strippability of ribbons, as a whole or in units, should be according to [IEC 60794-1-31] and as follows.
+
+At least 25 mm of the matrix and the fibres' protective coatings should be removable with commercially available stripping tools from aged and unaged ribbons. There should be no fibre breakage. Any remaining coating residue should be readily removable using isopropyl alcohol wipes. Ribbon ageing is under study. Stripping force should be measured using [IEC 60793-1-32] as applicable to the multiple fibres in a ribbon.
+
+#### **A.2.6 Cable element measurements**
+
+##### **A.2.6.1 Dimensions**
+
+Dimensions for other tubes, other ruggedized fibres, strength members, jackets or other cable elements should be as agreed between the manufacturer and customer.
+
+Measurement of these cable elements should use methods [IEC 60811-202] and [IEC 60811-203], as applicable.
+
+##### **A.2.6.2 Cable diameter**
+
+The cable outer diameter should not exceed the maximum stated by the manufacturer in accordance with [IEC 60794-2] series.
+
+The measurement should be in accordance with [IEC 60811-203].
+
+##### **A.2.6.3 Sheath thickness**
+
+The sheath thickness of indoor cable should be in accordance with [IEC 60794-2] series, or as alternatively agreed between the manufacturer and customer.
+
+Measurement should be in accordance with [IEC 60811-203].
+
+### **A.3 Test methods for mechanical characteristics of the cable**
+
+This clause recommends appropriate tests and test methods for verifying the mechanical characteristics of indoor cables.
+
+Performance and acceptance criteria and testing should comply with [IEC 60794-2] and the clauses below. Testing should be done according to [IEC 60794-1-21] and its subordinate specifications.
+
+In many cases, visual examination of an indoor cable during or after testing is appropriate.
+
+Visual examination of cables should be done using normal or normal corrected vision. Examination using magnification is needed. This provides the most effective combination of enlargement and depth-of-field.
+
+#### **A.3.1 Tensile strength**
+
+This test method applies to indoor cables installed under all environmental conditions. Measurements are made to examine the behaviour of the fibre attenuation and fibre strain as a function of the load on a cable during installation and during its lifetime.
+
+The cable should perform in accordance with [IEC 60794-2] series.
+
+The test should be carried out in accordance with [IEC 60794-1-21] method E1.
+
+There should be no damage to the sheath or cable elements under visual examination.
+
+#### **A.3.2 Bending**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to determine the ability of optical fibre cables to withstand coiling or bending around a pulley, simulated by a test mandrel.
+
+The cable should perform in accordance with [IEC 60794-2] series.
+
+This test should be carried out in accordance with [IEC 60794-1-21] method E11. The bending diameter should be according to clause 6.2.3. The mandrel or sheave diameter should be  $\pm 10\%$  of the specified value.
+
+#### **A.3.3 Bending under tension**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to determine the ability of an optical fibre cable to withstand bending around rollers or bows during installation, when a specified load is applied.
+
+The cables should perform in accordance with [IEC 60794-2-xx] and should be tested in accordance with [IEC 60794-1-21] method E18A, procedure 2.
+
+#### **A.3.4 Repeated bending**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to evaluate the ability of optical fibre cables to undergo the repeated bending associated with normal handling and service.
+
+The cable should perform in accordance with [IEC 60794-2] series and be tested in accordance with [IEC 60794-1-21] method E6.
+
+#### **A.3.5 Crush**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The appropriate test method for most terrestrial cables is the plate-plate crush method.
+
+The cable should perform in accordance with [IEC 60794-2] series and be tested in accordance with [IEC 60794-1-21] method E3A.
+
+#### **A.3.6 Impact**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to evaluate the ability of optical fibre cables to survive impacts associated with normal installation and handling.
+
+The cable should perform in accordance with [IEC 60794-2] series and be tested in accordance with [IEC 60794-1-21] method E4.
+
+#### **A.3.7 Torsion**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to evaluate the ability of optical fibre cables to accommodate the torsion associated with normal installation and handling.
+
+The cable should perform in accordance with [IEC 60794-2] series and be tested in accordance with [IEC 60794-1-21] method E7.
+
+#### **A.3.8 Abrasion of cable printing**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to evaluate the permanence of cable printing.
+
+The cable should perform in accordance with [IEC 60794-2] series and be tested in accordance with [IEC 60794-1-21] method E2A, method 2. This method tests the print using the felt pad method.
+
+After the test, the cable printing should still be legible.
+
+#### **A.3.9 Kinking**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+The purpose of this test is to evaluate the ability of optical fibre cables to undergo normal handling without kinking.
+
+This test should be carried out in accordance with [IEC 60794-1-21] method E10. The test criteria should be:
+
+- Test one sample;
+- Perform the test at ambient temperature.
+
+The cable should not kink at a loop diameter greater than the cable minimum bend diameter (see clause 6.2.3). There should be no attenuation requirement.
+
+#### **A.3.10 Coefficient of friction**
+
+This test method applies to all types of indoor cables for indoor application when it is necessary to consider the friction between cables or between cables and ducts.
+
+This test should be carried out in accordance with [IEC 60794-1-21] method E30 and method E34. Method 30 and 34 can be applied to evaluate the dynamic coefficient of friction for round-type and flat-type cables. The criteria of the coefficient of friction should be agreed between customers and suppliers.
+
+### **A.4 Test methods for environmental characteristics**
+
+This clause recommends the appropriate tests and test methods for verifying the environmental characteristics of indoor cables.
+
+Performance and acceptance criteria and testing should comply with [IEC 60794-2] and the clauses below. Testing should be done according to [IEC 60794-1-2] and its subordinate specifications.
+
+Appropriate temperature ranges are shown in clause 6.3.2, Table 1. Unless other temperature ranges are specified for particular applications, the values in Table 1 should be used.
+
+#### **A.4.1 Temperature cycling**
+
+This test method applies to indoor cables installed under all environmental conditions.
+
+Testing is carried out by temperature cycling to determine the stability of the attenuation of a cable due to temperature changes, which may occur during operation.
+
+The cable should perform in accordance with [IEC 60794-2] series and be tested in accordance with [IEC 60794-1-2] method F1 at the operational temperature per clause 6.3.2, Table 1. These temperatures are  $T_{A2}$  and  $T_{B2}$  of method F1. Other temperature values or intermediate values in method F1 should be as agreed between the manufacturer and customer.
+
+Attenuation changes at all temperatures should be calculated as deviations from the value at the initial measurement at ambient temperature.
+
+#### **A.4.2 Nuclear radiation**
+
+This test method assesses the suitability of optical fibre cables to be exposed to nuclear radiation.
+
+This test should be carried out in accordance with [IEC 60794-1-22] method F7.
+
+#### **A.4.3 Cable sheath adherence**
+
+This test applies to indoor cables installed under all environmental conditions. A range of installation techniques can apply a frictional force to the outer jacket, which may cause the jacket to slip with respect to the underlying cable – either in tension or compression.
+
+The test is applicable to cables in which the jacket is not adhesively bonded to the underlying cable structure. Generally, these are dielectric or metallic cables without strength members in the jacket or armoured cables, all with flooding compound applied over the inner structure or the shield or armour. Cables which are not water blocked are also subject to this test. Cables using a bonded armour construction are not tested due to the inherently high longitudinal bond strength of such constructions.
+
+The test measures the resistance of the cable sheath components (shield or armour and the overlaying jacket) to separation, one from another, by measuring the force required to pull the cable core and metallic covering out of the jacket.
+
+Cables should be tested according to [IEC 61196-1-313] or following the intent, as modified below. The test should be at expanded ambient temperature per clause A.1.4.
+
+##### **A.4.3.1 Test procedure**
+
+In using the terminology of the referenced test method, the "conductor" or "outer conductor" should be the core assembly without the jacket. The "dielectric" or "sheath" should be the cable jacket.
+
+The tested specimen should be of sufficient length to provide the test length of  $300\text{ mm} \pm 15\text{ mm}$ , per Figure A.1, and the prepared length of core and jacket. The prepared lengths of core and split jacket should be a length convenient for testing, generally about 100 mm each. The test may also be performed using the test plate of the referenced test rather than preparing the jacket.
+
+The test should be performed per [IEC 61196-1-313], as shown in Figure A.1, for illustration.
+
+![Diagram of the sheath adherence test apparatus and sample. A cable sample is shown with its outer sheath peeled back at an angle. The peeled sheath is held by a knurled mandrel at the top, and a force F is applied upwards. The cable sample is held by a clamp at the bottom, and a force F is applied downwards. The length of the cable sample between the clamp and the start of the peeled sheath is 300 mm (12 inches). The diagram is labeled L.104(25).](397d7c5f170e27a78f44fd8a5b0a234b_img.jpg)
+
+Diagram of the sheath adherence test apparatus and sample. A cable sample is shown with its outer sheath peeled back at an angle. The peeled sheath is held by a knurled mandrel at the top, and a force F is applied upwards. The cable sample is held by a clamp at the bottom, and a force F is applied downwards. The length of the cable sample between the clamp and the start of the peeled sheath is 300 mm (12 inches). The diagram is labeled L.104(25).
+
+**Figure A.1 – Sheath adherence test apparatus and sample**
+
+##### A.4.3.2 Requirements
+
+The sheath adherence should have a value greater than 14 N/mm of the circumference of the inner surface of the jacket. That circumference is most conveniently measured as the outer circumference of the armour, shield or underlying cable structure.
+
+### A.5 Test methods for electrical characteristics
+
+#### A.5.1 Electrical continuity
+
+The electrical continuity test is to verify that cable metallic elements are electrically continuous throughout the cable. This test is important for bonding and grounding, toning for location and other related system issues. Typically, the test should check continuity and should carry no resistance or conductivity requirement. The metallic elements may be tested individually or may be tested as a total group. Since this latter criterion is frequently the case, all elements are to be measured as a group unless specified otherwise.
+
+The test should be performed per [IEC 60794-1-403]. All metallic elements on the test should be electrically continuous.
+
+## A.6 Test methods for fire safety
+
+This clause recommends the appropriate tests and test methods for verifying the fire safety characteristics of optical fibre cables.
+
+#### A.6.1 Flame-retardant characteristics
+
+This test should be carried out in accordance with [IEC 60332-1-1], [IEC 60332-3-24] or [IEC 60332-3-25] unless there is a different agreement between the manufacturer and customer.
+
+#### **A.6.2 Toxic gases characteristics**
+
+This test should be carried out in accordance with [IEC 60754-1] or [IEC 60754-2] unless there is a different agreement between the manufacturer and customer.
+
+#### **A.6.3 Smoke characteristics**
+
+This test should be carried out in accordance with [IEC 61034-1] or [IEC 61034-2] unless there is a different agreement between the manufacturer and customer.
+
+NOTE – The item of fire safety should be considered according also to the national regulation of different countries.
+
+## Bibliography
+
+- [b-ITU-T G Suppl.40] ITU-T G-series Recommendations – Supplement 40 (2024), *Optical fibre and cable Recommendations and standards guideline.*
+- [b-IEC TR 63194] IEC TR 63194:2019, *Guidance on colour coding of optical fibre cables.*
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

marked/L/T-REC-L.1040-202208-I_PDF-E/raw.md

@@ -0,0 +1,493 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**L.1040**
+
+(08/2022)
+
+SERIES L: ENVIRONMENT AND ICTS, CLIMATE  
+CHANGE, E-WASTE, ENERGY EFFICIENCY;  
+CONSTRUCTION, INSTALLATION AND PROTECTION  
+OF CABLES AND OTHER ELEMENTS OF OUTSIDE  
+PLANT
+
+E-waste and circular economy
+
+---
+
+**Effects of information and communication  
+technology-enabled autonomy on vehicles  
+longevity and waste creation**
+
+Recommendation ITU-T L.1040
+
+# ITU-T L-SERIES RECOMMENDATIONS
+
+## ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT
+
+|                                                        |                      |
+|--------------------------------------------------------|----------------------|
+| OPTICAL FIBRE CABLES                                   |                      |
+| Cable structure and characteristics                    | L.100–L.124          |
+| Cable evaluation                                       | L.125–L.149          |
+| Guidance and installation technique                    | L.150–L.199          |
+| OPTICAL INFRASTRUCTURES                                |                      |
+| Infrastructure including node elements (except cables) | L.200–L.249          |
+| General aspects and network design                     | L.250–L.299          |
+| MAINTENANCE AND OPERATION                              |                      |
+| Optical fibre cable maintenance                        | L.300–L.329          |
+| Infrastructure maintenance                             | L.330–L.349          |
+| Operation support and infrastructure management        | L.350–L.379          |
+| Disaster management                                    | L.380–L.399          |
+| PASSIVE OPTICAL DEVICES                                | L.400–L.429          |
+| MARINIZED TERRESTRIAL CABLES                           | L.430–L.449          |
+| <b>E-WASTE AND CIRCULAR ECONOMY</b>                    | <b>L.1000–L.1199</b> |
+| POWER FEEDING AND ENERGY STORAGE                       | L.1200–L.1299        |
+| ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES | L.1300–L.1399        |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES  | L.1400–L.1499        |
+| ADAPTATION TO CLIMATE CHANGE                           | L.1500–L.1599        |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES        | L.1600–L.1699        |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                    | L.1700–L.1799        |
+
+For further details, please refer to the list of ITU-T Recommendations.
+
+## Recommendation ITU-T L.1040
+
+# Effects of information and communication technology-enabled autonomy on vehicles longevity and waste creation
+
+## Summary
+
+Recommendation ITU-T L.1040 establishes guidelines and requirements for information and communication technology original equipment manufacturer vendors providing equipment to autonomous vehicles aiming to reduce the amount of future e-waste.
+
+Recommendation ITU-T L.1040 analyses the e-waste risks and other sustainability indicators of autonomous vehicles and proposes how these potential challenges can be mitigated.
+
+Recommendation ITU-T L.1040 utilizes information compiled from stakeholders that can provide good insights into the specified potential challenge.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T L.1040   | 2022-08-13 | 5           | <a href="http://handle.itu.int/11.1002/1000/15024">11.1002/1000/15024</a> |
+
+### Keywords
+
+Autonomous vehicles, ICT e-waste.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+### INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2022
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|     |                                                                                                                                             |    |
+|-----|---------------------------------------------------------------------------------------------------------------------------------------------|----|
+| 1   | Scope .....                                                                                                                                 | 1  |
+| 2   | References.....                                                                                                                             | 1  |
+| 3   | Terms .....                                                                                                                                 | 1  |
+| 3.1 | Terms defined elsewhere .....                                                                                                               | 1  |
+| 3.2 | Terms defined in this Recommendation.....                                                                                                   | 2  |
+| 4   | Abbreviations and acronyms .....                                                                                                            | 2  |
+| 5   | Conventions .....                                                                                                                           | 2  |
+| 6   | Autonomous vehicles and e-waste .....                                                                                                       | 2  |
+| 6.1 | Hazardous substances .....                                                                                                                  | 2  |
+| 6.2 | Eco-friendly materials and recyclable materials .....                                                                                       | 2  |
+| 6.3 | Standardized model and modular design.....                                                                                                  | 3  |
+| 6.4 | Standardized essential components .....                                                                                                     | 3  |
+| 6.5 | Reparability and maintainability .....                                                                                                      | 3  |
+| 6.6 | Remanufacturing .....                                                                                                                       | 3  |
+| 6.7 | Replaceable software.....                                                                                                                   | 3  |
+| 6.8 | Upgrade compatibility .....                                                                                                                 | 3  |
+| 6.9 | Greenhouse gas emissions .....                                                                                                              | 3  |
+| 7   | Assessing the longevity of the ICT components of an autonomous vehicle .....                                                                | 3  |
+| 7.1 | Usage and mileage.....                                                                                                                      | 3  |
+| 7.2 | Remote monitoring.....                                                                                                                      | 4  |
+| 7.3 | Critical part.....                                                                                                                          | 4  |
+| 7.4 | Test and verification .....                                                                                                                 | 4  |
+|     | Annex A – Scorecard for guidelines and requirements evaluation.....                                                                         | 5  |
+|     | Appendix I – Model for estimating ICT and battery waste generation from vehicles<br>including autonomous and battery electric vehicles..... | 8  |
+|     | Bibliography.....                                                                                                                           | 11 |
+
+## Introduction
+
+Longevity (durability) is the most important aspect for lowering environmental impact in a circular economy. At the same time ~80 million new automotive vehicles – electric and others – are sold annually and ~1 billion are out on the streets. Other vehicles, like fleets of large commercial trucks and aircraft, account for ~250 million and ~25 000, respectively. All automotive autonomous vehicles (AVs) contain a significant value – and amount – of information and communication technology (ICT). The mass of ICT hardware (HW) per vehicle is expected to rise from ~20 kg to ~60 kg for AVss defined by software (SW) and other e-vehicles. The trend is that several (most) AVs (battery electric vehicles (BEVs) and others) will be equipped with ICT solutions that make them autonomous, i.e., they can "drive by themselves". There is a clear risk that the average lifetime of SW-defined AVs will be much shorter than for ordinary internal combustion engine vehicles (ICEVs). This could lead to additional e-waste creation.
+
+There are several reasons why SW-defined AVs – usually BEVs – may have shorter lifetimes than conventional. In general, similar to consumer ICT goods, AV may involve high usability and frequent updates of both new models and SW. AVs and BEVs usually refer to next generation vehicles using more functionality than typical ICEVs.
+
+High usability results in high kilometrage, which affects the lifespan of the vehicle. Compared to ICEVs, AVs and BEVs may provide an easier, less costly, and more comfortable driving experience. Therefore, private usage daily driving may increase sharply, leading to more wear.
+
+As in the consumer ICT industry, new technologies will likely accelerate the innovation of new models in the AV industry. Moreover, the design and launch time of AVs may be short. Additionally, consumers may be encouraged to buy new AV models more often than ICEVs, and this might increase the amounts of ICT-related AV waste. It has been estimated that 10-12 years elapse before ICEVs are scrapped but only 4 years for AVs/BEVs. AVs or BEVs may have three times the amount (~60 kg/unit) of ICT HW as current ICEVs (~20 kg/ICEV unit).
+
+The number of BEVs and fuel cell vehicles put on the market is expected to increase more rapidly from 2020 to 2030 or 2040 than between 2010 and 2020. In 2040, this may generate an additional 2 to 4 Mt of AV or BEV ICT waste and ~8 Mt battery waste. The model used to estimate certain waste and greenhouse gases from production of vehicles globally is discussed in Appendix I.
+
+SW upgrades may overtake those of HW. AVs rely highly on the control system, and like technology upgrades, those for SW may be required in a shorter period, while vehicle HW – such as components, parts, and sensors – cannot be replaced as easily or as quickly.
+
+## Recommendation ITU-T L.1040
+
+## Effects of information and communication technology-enabled autonomy on vehicles longevity and waste creation
+
+## 1 Scope
+
+This Recommendation establishes guidelines and requirements for information and communication technology original equipment manufacturer vendors providing equipment to autonomous vehicles aiming to reduce the amount of future e-waste.
+
+This Recommendation analyses the e-waste risks and other sustainability indicators of autonomous vehicles and proposes how these potential challenges can be mitigated.
+
+This Recommendation utilises information compiled from stakeholders that can provide good insights into the specified potential challenge.
+
+This Recommendation contains an analysis of the longevity of autonomous vehicle (AVs). It is plausible that the lifetime of information and communication technology (ICT) components inside AVs could be shorter than manually driven internal combustion engine vehicles (ICEVs). If so, additional e-waste – and other waste – may be created. The Recommendation also considers the possible solutions to the problems arising from waste creation caused by ICT enabled AVs. The Recommendation contains a guide for best practice design for longevity of AVs at a global level.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ITU-T L.1410] Recommendation ITU-T L.1410 (2014), *Methodology for environmental life cycle assessments of information and communication technology goods, networks and services*.
+
+## 3 Terms and definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 autonomous vehicle** [b-AR]: Vehicle equipped with an automated driving system that can drive the vehicle for any duration of time without the active physical control or monitoring of a human operator.
+
+**3.1.2 battery electric vehicle** [b-LI]: Vehicle that operates exclusively on electrical energy from an off-board source that is stored in the vehicle's batteries, and produces zero tailpipe emissions or pollution when stationary or operating.
+
+**3.1.3 fuel cell vehicle** [b-UNECE]: Vehicle with a fuel cell and an electric machine as propulsion energy converters.
+
+**3.1.4 hazardous substance** [b-ISO/TS 22002-5]: Solid, liquid or gas that is radioactive, flammable, explosive, corrosive, oxidizing, asphyxiating, pathogenic or allergenic, including, but not
+
+restricted to, detergents, sanitizers, pest control chemicals, lubricants, paints, processing aids and biochemical additives, which, if used or handled incorrectly or in increased dosage, could cause harm to the handler and/or consumer
+
+### **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following term:
+
+**3.2.1 software-defined autonomous vehicle:** Autonomous vehicle whose intelligence is largely delivered through software.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                          |
+|------|------------------------------------------|
+| AV   | Autonomous Vehicle                       |
+| BEV  | Battery Electric Vehicle                 |
+| GHG  | Greenhouse Gas                           |
+| HW   | Hardware                                 |
+| ICT  | Information and Communication Technology |
+| ICEV | Internal Combustion Engine Vehicle       |
+| OS   | Operating System                         |
+| SW   | Software                                 |
+
+## **5 Conventions**
+
+None.
+
+## **6 Autonomous vehicles and e-waste**
+
+Clauses 6.1 to 6.8 list several guidelines and requirements that may decrease eco-impacts, detoxify and reduce e-waste related to ICT hardware (HW) in AVs or battery electric vehicles (BEVs).
+
+### **6.1 Hazardous substances**
+
+- Manufacturers shall ensure that the ICT HW of AVs at least be in harmony with the *End of life vehicle directive* (available from [b-EC ELV]) and its revision.
+- Manufacturers should avoid the use of hazardous substances.
+- Manufacturers should encourage the reduction of number of chemical categories used in production.
+
+NOTE 1 – The material composition is relevant for fire safety aspects of AVs/BEVs.
+
+NOTE 2 – Ever higher voltage is the general trend for batteries. Higher voltage may increase the risk of fire and emissions of hazardous substances.
+
+### **6.2 Eco-friendly materials and recyclable materials**
+
+- Manufacturers should use eco-friendly and recyclable materials for ICT HW in AVs.
+- Manufacturers should develop eco-friendly and recyclable materials or parts for ICT HW in AVs.
+- Manufacturers should use the simplest possible painting for ICT HW in AVs where applicable.
+
+### **6.3 Standardized model and modular design**
+
+- The degree of modularity (generic building block design) should be determined for ICT HW in AVs.
+
+### **6.4 Standardized essential components**
+
+- All components used shall conform to criteria in international standards, e.g., on safety and performance.
+
+### **6.5 Reparability and maintainability**
+
+- The degree of reparability should be determined for ICT HW in AVs.
+- The degree of maintainability should be determined for ICT HW in AVs.
+
+### **6.6 Remanufacturing**
+
+- The ability of ICT HW for AVs to be remanufactured should be maximized.
+- The degree of ability to be remanufactured should be determined for ICT HW for AVs.
+- The degree of ability of parts and components to be reused should be determined for ICT HW for AVs.
+
+### **6.7 Replaceable software**
+
+- The degree of replaceable and harmonized operating system (OS) (in the microcontroller HW) should be determined for ICT HW in AVs.
+
+NOTE – Refers to the ability to replace the microcontroller.
+
+- The OS should be developed from common principles of modularity and scalability.
+- The degree of compatibility of all OS with all current AV models, and *vice versa*, should be determined for ICT HW in AVs.
+- The degree of compatibility of all OSs of customized software (SW) applications with all models, should be determined for ICT HW in AVs.
+- The degree of SW change burden on HW change should be determined for ICT HW in AVs.
+- ICT HW should be future proof and backward compatible.
+
+### **6.8 Upgrade compatibility**
+
+- SW updates should be compatible with current ICT HW.
+- HW updates should be compatible with current SW.
+
+### **6.9 Greenhouse gas emissions**
+
+- Manufacturers should quantify the amount of greenhouse gas (GHG) emissions with life cycle assessment (LCA) from upstream, distribution, use and end-of-first life according to [ITU-T L.1410] for ICT HW in AVs.
+
+## **7 Assessing the longevity of the ICT components of an autonomous vehicle**
+
+Clauses 7.1 to 7.4 list several guidelines that may increase the longevity of ICT HW in AVs.
+
+### **7.1 Usage and mileage**
+
+- Manufacturers should set the minimum kilometrage and lifespan for AVs.
+- Manufacturers should commit resources to maintain ICT HW in AVs.
+
+### **7.2 Remote monitoring**
+
+- Manufacturers should provide remote monitoring of AV usage and assess AV usage time and lifespan.
+
+### **7.3 Critical part**
+
+- The lifespan of critical (priority) parts should be assessed or verified according to international standards.
+
+### **7.4 Test and verification**
+
+- Moderate or frequent testing and verification should be considered for AV condition and lifespan.
+
+## Annex A
+
+### Scorecard for guidelines and requirements evaluation
+
+(This annex forms an integral part of this Recommendation.)
+
+**Table A.1 – Scorecard for guidelines and requirements for evaluation**
+
+| Guideline or requirements                                                                                                | Clause | Met    | Unmet  |
+|--------------------------------------------------------------------------------------------------------------------------|--------|--------|--------|
+| Ensuring ICT HW in AVs is at least in harmony with the ELV directive. (requirement)                                      | 6.1    | Yes/No | Yes/No |
+| Avoidance of hazardous substance use.                                                                                    | 6.1    | Yes/No | Yes/No |
+| Encouragement of the reduction of number of chemical categories used in production.                                      | 6.1    | Yes/No | Yes/No |
+| Use of eco-friendly and recyclable materials for ICT HW in AVs.                                                          | 6.2    | Yes/No | Yes/No |
+| Development of eco-friendly and recyclable materials or parts for ICT HW in AVs.                                         | 6.2    | Yes/No | Yes/No |
+| Use of the simplest possible painting for ICT HW in AVs where applicable.                                                | 6.2    | Yes/No | Yes/No |
+| Determination of the degree of modularity (generic building block design) for ICT HW in AVs.                             | 6.3    | Yes/No | Yes/No |
+| Conformity of all components used to criteria in international standards, e.g., on safety and performance. (requirement) | 6.4    | Yes/No | Yes/No |
+| Determination of the degree of reparability for ICT HW in AVs.                                                           | 6.5    | Yes/No | Yes/No |
+| Determination of the degree of maintainability for ICT HW in AVs.                                                        | 6.5    | Yes/No | Yes/No |
+
+**Table A.1 – Scorecard for guidelines and requirements for evaluation**
+
+| <b>Guideline or requirements</b>                                                                                               | <b>Clause</b> | <b>Met</b> | <b>Unmet</b> |
+|--------------------------------------------------------------------------------------------------------------------------------|---------------|------------|--------------|
+| Maximization of the ability of ICT HW in AVs to be remanufactured.                                                             | 6.6           | Yes/No     | Yes/No       |
+| Determination of the degree of ability to be remanufactured for ICT HW in AVs.                                                 | 6.6           | Yes/No     | Yes/No       |
+| Determination of the degree of ability of parts and components to be reused for ICT HW in AVs.                                 | 6.6           | Yes/No     | Yes/No       |
+| Determination of the degree of replaceable and harmonized OS (in the microcontroller HW) for ICT HW in AVs.                    | 6.7           | Yes/No     | Yes/No       |
+| Development of the OS from common principles of modularity and scalability.                                                    | 6.7           | Yes/No     | Yes/No       |
+| Determination of the degree of compatibility of all OSs with all current AV models, and <i>vice versa</i> , for ICT HW in AVs. | 6.7           | Yes/No     | Yes/No       |
+| Determination of the degree of compatibility of all OSs of customized SW applications with all models, for ICT HW in AVs.      | 6.7           | Yes/No     | Yes/No       |
+| Determination of the degree of SW change burden on hardware change for ICT HW in AVs.                                          | 6.7           | Yes/No     | Yes/No       |
+| Ensuring that ICT HW is future proof and backward compatible.                                                                  | 6.7           | Yes/No     | Yes/No       |
+| Ensuring that SW updates are compatible with current ICT HW.                                                                   | 6.8           | Yes/No     | Yes/No       |
+
+**Table A.1 – Scorecard for guidelines and requirements for evaluation**
+
+| <b>Guideline or requirements</b>                                                                                                                           | <b>Clause</b> | <b>Met</b> | <b>Unmet</b> |
+|------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------|------------|--------------|
+| Ensuring that hardware updates are compatible with current SW.                                                                                             | 6.8           | Yes/No     | Yes/No       |
+| Quantification of the amount of GHG emissions by LCA from upstream, distribution, use and end-of-first life according to [ITU-T L.1410] for ICT HW in AVs. | 6.9           | Yes/No     | Yes/No       |
+| Setting the minimum kilometrage and lifespan for AVs.                                                                                                      | 7.1           | Yes/No     | Yes/No       |
+| Commitment of resources to maintain ICT HW in AVs.                                                                                                         | 7.1           | Yes/No     | Yes/No       |
+| Provision of remote monitoring for AV usage and assessment of the usage time and lifespan.                                                                 | 7.2           | Yes/No     | Yes/No       |
+| Assessment or verification of the lifespan of critical (priority) parts according to international standards.                                              | 7.3           | Yes/No     | Yes/No       |
+| Consideration of moderate or frequent testing and verification of AV condition and lifespan.                                                               | 7.4           | Yes/No     | Yes/No       |
+
+## Appendix I
+
+### Model for estimating ICT and battery waste generation from vehicles including autonomous and battery electric vehicles
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix outlines the schematics and main assumptions in a model used to estimate annual global ICT and battery waste generation as a result of variable lifespan of AVs or BEVs.
+
+Similarly to Equation 5 of [b-Islam], as far as annual ICT HW waste generation, this model for calculating total mass of ICT HW from AV vehicles waste in year 2010, etc. features in principle:
+
+- "year"
+- "category of AV vehicle that contains ICT HW, which becomes e-waste"
+- "total number of units of category of AV vehicle which contains ICT HW sold in year 2010, etc."
+- "net mass of the ICT HW in the AV vehicle in the year 2010, etc."
+- "failure rate of AV vehicle that contains ICT HW since year 2010".
+
+ICEV cars are assumed to decline from 95% market share of those sold in 2010 to 41% in 2040.
+
+Hybrid, BEV ("Light EV") and FCEV vehicles are assumed to increase from 5% market share in 2010 to 58% in 2040.
+
+ICEV trucks are assumed to decline from 100% market share of trucks sold in 2010 to 66% in 2040.
+
+AV or BEV ("Heavy EV") and FCEV trucks are assumed to increase from ~0% market share of trucks sold in 2010 to 34% in 2040.
+
+If the lifespan of ICT HW in AVs or BEVs is set to 4 years, the first e-waste is generated in 2013.
+
+If the lifespan of the ICT HW in AVs or BEVs is set to 8 years, the first e-waste is delayed and generated in 2017. The more AVs or BEVs that are produced, the more e-waste is potentially generated.
+
+If the lifespan of the battery HW in AVs or BEVs is set to 6 years, the first e-waste is generated in 2015. However, p. 4 of [b-Curt] argues that BEV batteries first lifespan is 10-15 years and may have a second life of 10 years.
+
+#### Traditional ICEV car assumptions
+
+20 kg ICT HW and 25 kg batteries per vehicle.
+
+#### Hybrid car assumptions
+
+25 kg ICT HW and 40 kg batteries per vehicle.
+
+#### AV or BEV car assumptions
+
+60 kg ICT HW per vehicle and 240 kg battery per vehicle.
+
+#### FCEV car assumptions
+
+60 kg ICT HW per vehicle. Fuel cell waste is not included.
+
+#### Traditional ICEV truck assumptions
+
+40 kg ICT HW and 100 kg batteries per truck.
+
+#### AV ICEV truck assumptions
+
+100 kg ICT HW per vehicle.
+
+#### FCEV truck assumptions
+
+100 kg ICT HW per vehicle. Fuel cell waste is not included.
+
+#### Electric truck assumptions
+
+100 kg ICT HW and 400 kg battery per vehicle.
+
+### Carbon
+
+From 2010 to 2040 the kilogram CO<sub>2</sub>-equivalents per kilogram of ICT HW is assumed to be on average around 300 kg/kg.
+
+Table I.1 shows the key results for e-waste generation as a result of introducing AVs.
+
+**Table I.1 – Key results for e-waste and battery waste generation and greenhouse gas emissions for vehicles 2010 to 2040**
+
+|                                                                                 | 2010  | 2015    | 2020  | 2025  | 2030  | 2035  | 2040  |
+|---------------------------------------------------------------------------------|-------|---------|-------|-------|-------|-------|-------|
+| <b>E-waste</b>                                                                  |       |         |       |       |       |       |       |
+| 1) E-waste from all vehicles, 8 year lifetime of ICT (Mt)                       |       |         | 2.5   | 2.9   | 3.0   | 4.1   | 5.8   |
+| 1.1) E-waste from AVs or BEVs, 8 year lifetime of ICT (Mt)                      |       |         | 0.005 | 0.082 | 0.23  | 0.78  | 2.1   |
+| 2) E-waste from all vehicles, 4 years lifetime of ICT (Mt)                      |       | 2.4     | 2.8   | 2.9   | 3.8   | 5.4   | 7.6   |
+| 2.1) E-waste from AVs or BEVs, 4 year lifetime of ICT (Mt)                      |       | 0.002 4 | 0.067 | 0.18  | 0.63  | 1.8   | 3.7   |
+| 2.2) E-waste from AV ICEV trucks, 4 year lifetime of ICT HW (Mt)                |       |         |       | 0.012 | 0.042 | 0.014 | 0.026 |
+| <b>Battery waste</b>                                                            |       |         |       |       |       |       |       |
+| 6) Battery waste from all vehicles, 6 year lifetime of battery (Mt)             |       | 3.9     | 4.5   | 4.8   | 6.4   | 9.6   | 15    |
+| 7) Battery waste from all kinds of AVs or BEVs, 6 year lifetime of battery (Mt) |       | 0.001 8 | 0.063 | 0.37  | 1.2   | 3.6   | 8.3   |
+| <b>Greenhouse gas emissions</b>                                                 |       |         |       |       |       |       |       |
+| 8) GHG from all vehicles production (Mt CO <sub>2</sub> -equivalents)           | 1 400 | 1 600   | 1 500 | 1 700 | 2 000 | 2 300 | 2 700 |
+| 9) ICT HW GHG from AV or BEV production (Mt CO <sub>2</sub> -equivalents)       | 0.14  | 4.7     | 28    | 110   | 380   | 830   | 1 700 |
+| 10) ICT sector GHG (Mt CO <sub>2</sub> -equivalents)                            | 1 100 | 1 100   | 1 100 | 1 100 | 1 700 | 2 100 | 2 600 |
+
+As shown in Table A.1, the proportion of AV or BEV ICT hardware production-related GHGs – of ICT sector GHGs – in 2020, 2030 and 2040 will be around 3%, 22% and 64%, respectively. ICT sector GHG levels for 2035 and 2040 are extrapolated from [b-Andrae] estimations from 2019 to 2030.
+
+GHGs produced by AV or BEV ICT HW as a fraction of total vehicle production is projected to increase towards 2040.
+
+ICT HW waste from emerging AVs or BEVs of the total ICT HW vehicle waste is projected to increase towards 2040. The trends are similar for battery vehicle waste.
+
+Page 5 of [b-Melin] estimates that light EV and heavy EV will generate some 0.075, 0.3 and 1.4 Mt lithium-ion batteries for recycling in 2020, 2025 and 2030, respectively. These numbers are quite close to those in row 7) of Table A.1, suggesting that the present model makes sense.
+
+Another finding is that this model estimates 1.55 million AV or BEV sales in 2020. For 2020, this fits rather well with [b-IEA], which reckons 2.8 million EV placed on the market. Moreover [b-InsideEVs] indicates that the total battery market in 2020 was 142.8 GWh, Then Table 1 of [b-Zheng] estimates around 30 kW h battery capacity per BEV, leading to 4.76 million (see Note) AV or BEV sales in 2020. The 4.76 million figure is comparable to this model's forecast for 2020 of 6.22 million hybrid (4.66 million) battery and plug-in electric vehicles (1.55 million).
+
+NOTE – 142.8 GWh amount for light EV divided by 30 kWh per light EV.
+
+It also aligns with the prediction in Figure 1 of [b-di Paolo Emilio] of 2% plug-in hybrid and EV of all light vehicles put on the market.
+
+## Bibliography
+
+- [b-ISO/TS 22002-5] ISO Technical Specification 22002-5:2019, *Prerequisite programmes on food safety – Part 5: Transport and storage*.
+- [b-IEA] IEA (2021). *Global EV sales by scenario, 2020-2030*. Paris: International Energy Agency. Available [viewed 2022-09-21] at: <https://www.iea.org/data-and-statistics/charts/global-ev-sales-by-scenario-2020-2030>
+- [b-UNECE] E/ECE/324/Rev.2/Add.137/Rev.1 (2017). *Agreement concerning the adoption of harmonized technical United Nations regulations for wheeled vehicles, equipment and parts which can be fitted and/or be used on wheeled vehicles and the conditions for reciprocal recognition of approvals granted on the basis of these United Nations regulations*. Geneva: United Nations Economic Commission for Europe. 40 pp. Available [viewed 2022-09-15] at: <https://unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2017/R138r1e.docx>
+- [b-Andrae] Andrae, A.S.G. (2021). Internet's handprint. *Eng. Appl. Sci. Lett.* **4**, pp. 80-97. doi: 10.30538/psrp-easl2021.0065
+- [b-AR] Arkansas Department of Transportation (2020). *Autonomous vehicle pilot program rules*. Little Rock, AR: Bureau of Legislative Research. 10 pp. Available [viewed 2022-09-15] at: <https://www.arkleg.state.ar.us/Calendars/Attachment?committee=040&agenda=3557&file=D.16a+ArDOT+ASHC+Autonomous+Vehicle+Pilot+Program+Rules+and+Relevant+Acts.pdf>
+- [b-Curt] Curt, J.D. (2019), The potential and benefits of second-life EV batteries [unpublished]. Paper presented at; E-waste World Conference 2019-11-14, Frankfurt, Germany.
+- [b-di Paolo Emilio] di Paolo Emilio, M. (2020). Electric vehicles: 48 V is the new 12 V. *Power Electron, News* (Internet). Available [viewed 2022-09-15] at: <https://www.poweerelectronicsnews.com/electric-vehicles-48v-is-the-new-12v/>
+- [b-EC ELV] European Commission (Internet). *End-of-life vehicles*. Brussels: European Commission. Available [viewed 2022-09-15] at: [https://ec.europa.eu/environment/topics/waste-and-recycling/end-life-vehicles\\_en](https://ec.europa.eu/environment/topics/waste-and-recycling/end-life-vehicles_en)
+- [b-InsideEVs] Kane, M. (2021). *SNE Research: Global xEV battery market – 142.8 GWh in 2020*. Miami, FL: InsideEVs. Available [viewed 2022-09-21] at: <https://insideevs.com/news/488274/sne-research-global-xev-battery-market-2020/>
+- [b-Islam] Islam, M. T., Huda, N. (2020). Assessing the recycling potential of "unregulated" e-waste in Australia. *Resour. Conserv. Recycl.* **152**, 104526. doi: 10.1016/j.resconrec.2019.104526
+- [b-LI] Law Insider (Internet). *Law insider*. San Francisco, CA: Law Insider. Available [viewed 2022-09-15] at: <https://www.lawinsider.com>
+- [b-Melin] Melin, H.E. (2019), *The EV battery – The key to a circular industry* [unpublished]. Paper presented at: E-waste World Conference 2019-11-14, Frankfurt, Germany.
+- [b-Zheng] Zheng, G., Peng, Z. (2021). Life cycle assessment (LCA) of BEV's environmental benefits for meeting the challenge of ICExit (internal combustion engine exit). *Energy Rep.* **7**, pp. 1203-1216. doi: 10.1016/j.egyrep.2021.02.039
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

marked/L/T-REC-L.108-201803-I_PDF-E/raw.md

@@ -0,0 +1,894 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**L.108**
+
+(03/2018)
+
+SERIES L: ENVIRONMENT AND ICTS, CLIMATE  
+CHANGE, E-WASTE, ENERGY EFFICIENCY;  
+CONSTRUCTION, INSTALLATION AND PROTECTION  
+OF CABLES AND OTHER ELEMENTS OF OUTSIDE  
+PLANT
+
+Optical fibre cables – Cable structure and characteristics
+
+# --- **Optical fibre cable elements for microduct blowing-installation application**
+
+Recommendation ITU-T L.108
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+## ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT
+
+|                                                        |                    |
+|--------------------------------------------------------|--------------------|
+| OPTICAL FIBRE CABLES                                   |                    |
+| <b>Cable structure and characteristics</b>             | <b>L.100–L.124</b> |
+| Cable evaluation                                       | L.125–L.149        |
+| Guidance and installation technique                    | L.150–L.199        |
+| OPTICAL INFRASTRUCTURES                                |                    |
+| Infrastructure including node elements (except cables) | L.200–L.249        |
+| General aspects and network design                     | L.250–L.299        |
+| MAINTENANCE AND OPERATION                              |                    |
+| Optical fibre cable maintenance                        | L.300–L.329        |
+| Infrastructure maintenance                             | L.330–L.349        |
+| Operation support and infrastructure management        | L.350–L.379        |
+| Disaster management                                    | L.380–L.399        |
+| PASSIVE OPTICAL DEVICES                                | L.400–L.429        |
+| MARINIZED TERRESTRIAL CABLES                           | L.430–L.449        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.108
+
+# Optical fibre cable elements for microduct blowing-installation application
+
+## Summary
+
+Recommendation ITU-T L.108 (ex. L.79) describes the characteristics, construction and test methods for microduct fibre units and microduct cables that are used with the blowing installation technique. The cable characteristics required for a cable to perform appropriately are described. Also, a method is described for determining whether or not the cable has the required characteristics. The required conditions may differ according to the installation environment; detailed test conditions must be agreed upon between a user and a manufacturer for the environment in which a cable is to be used.
+
+## History
+
+| Edition | Recommendation   | Approval   | Study Group | Unique ID*                                                                |
+|---------|------------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T L.108/L.79 | 2008-07-07 | 6           | <a href="http://handle.itu.int/11.1002/1000/9429">11.1002/1000/9429</a>   |
+| 2.0     | ITU-T L.108      | 2018-03-16 | 15          | <a href="http://handle.itu.int/11.1002/1000/13565">11.1002/1000/13565</a> |
+
+## Keywords
+
+Blowing installation, fibre unit, microcable, microduct, optical fibre cable.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2018
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|              |                                                                                            | Page |
+|--------------|--------------------------------------------------------------------------------------------|------|
+| 1            | Scope.....                                                                                 | 1    |
+| 2            | References.....                                                                            | 1    |
+| 3            | Definitions .....                                                                          | 3    |
+| 3.1          | Terms defined elsewhere .....                                                              | 3    |
+| 3.2          | Terms defined in this Recommendation.....                                                  | 3    |
+| 4            | Abbreviations and acronyms .....                                                           | 4    |
+| 5            | Conventions .....                                                                          | 4    |
+| 6            | Environmental conditions .....                                                             | 4    |
+| 6.1          | Underground.....                                                                           | 4    |
+| 6.2          | Aerial .....                                                                               | 4    |
+| 6.3          | Indoor .....                                                                               | 4    |
+| 7            | Construction and characteristics of microduct system and cable elements .....              | 4    |
+| 7.1          | Fibre.....                                                                                 | 4    |
+| 7.2          | Blown-in elements.....                                                                     | 5    |
+| 7.3          | Microducts.....                                                                            | 6    |
+| 7.4          | Protected microducts .....                                                                 | 6    |
+| 7.5          | Composite protected microduct/cable .....                                                  | 7    |
+| 8            | Test methods .....                                                                         | 7    |
+| 8.1          | Test methods for dimensions .....                                                          | 7    |
+| 8.2          | Test methods for cable elements .....                                                      | 7    |
+| 8.3          | Methods for testing mechanical characteristics.....                                        | 8    |
+| 8.4          | Test methods for environmental characteristics .....                                       | 10   |
+| 8.5          | Test methods for fire safety .....                                                         | 11   |
+| 8.6          | Test methods for installation performance .....                                            | 11   |
+| Appendix I   | – Chinese experience .....                                                                 | 12   |
+| I.1          | Product types of microducts .....                                                          | 12   |
+| I.2          | Microduct inner clearance verification.....                                                | 13   |
+| I.3          | Blowing performance test for microcables or fibre units in microduct.....                  | 14   |
+| I.4          | Layout location selection for microduct.....                                               | 16   |
+| Appendix II  | – Chinese experience on effects of freezing conditions on microduct air-blown cables ..... | 17   |
+| II.1         | Introduction .....                                                                         | 17   |
+| II.2         | Freezing test.....                                                                         | 17   |
+| II.3         | Conclusion.....                                                                            | 20   |
+| Bibliography | .....                                                                                      | 21   |
+
+# Introduction
+
+Air blowing installation methods are based on viscous drag acting upon a cable within a duct by forcing a continuous high-speed airflow through the duct. The velocity of the moving air propels the cable and makes it advance at a typical speed supported by the blowing equipment. When using blowing techniques, there is generally no pulling force at the front end of the cable; the airflow exerts a distributed force along the entire cable. In addition, connection to a pulling cord is not needed.
+
+Generally, the blowing force is an order of magnitude lower than the typical force involved in other installation methods, for example pulling techniques, thus reducing installation hazards. Additionally, with this technique, bends in a duct run are of less concern than with pulling techniques, so, generally, the installation speed increases and longer lengths of cable can be installed. Cables are installed with low stress levels, leaving the cable or other elements effectively relaxed in the duct once the installation has been completed.
+
+Therefore, cables can be designed with lower tensile capabilities than cables to be pulled. And, elements without additional strength members, such as fibre units and single fibres, can also be considered.
+
+New generation cabling techniques, based on microduct cables, microduct fibre units and microduct systems, offer the possibility of branching without the need for splices. These techniques are extremely flexible and make them possible to grow in accordance with demand. This gives rise to the concept of "fibre on demand", which involves the pre-installation of a multi-microduct system and then the subsequent, incremental installation of fibres based on individual customer demand.
+
+To support this "fibre on demand" approach, a fibre cable product must allow the installation of only a few fibres at a time. These types of cable products should take up the smallest possible amount of the service provider's right-of-way (i.e., fit the smallest microduct) so that there is plenty of space to add fibres for future customers. Therefore, usually only a small number of the fibres that are installed are used immediately. Also, the latest fibre technology can be adopted when required.
+
+# Recommendation ITU-T L.108
+
+# Optical fibre cable elements for microduct blowing-installation application
+
+# 1 Scope
+
+This Recommendation:
+
+- refers to microduct fibre units and microduct cables to be used for telecommunication networks with blowing installation techniques;
+- deals with mechanical and environmental characteristics of microduct fibre units and microduct cables. The optical fibre dimensional and performance parameters, together with their test methods, should comply with [IEC 60793-5-10] or [IEC 60794-5-20] which deal with microduct cable and microduct fibre units, respectively. The optical fibre dimensional and transmission characteristics, together with their test methods, should comply with [IEC 60793-2-10] and with [ITU-T G.651.1], [ITU-T G.652], [ITU-T G.653], [ITU-T G.654], [ITU-T G.655], [ITU-T G.656] and [ITU-T G.657] which deal with multi-mode graded index optical fibres and single-mode optical fibres, respectively;
+- acknowledges that some optical fibre cables may contain metallic elements, for which reference should be made to [b-ITU-T Technical Report] and other L-series Recommendations.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T G.650.1] Recommendation ITU-T G.650.1 (2018), *Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable*.
+- [ITU-T G.651.1] Recommendation ITU-T G.651.1 (2007), *Characteristics of a 50/125 µm multimode graded index optical fibre cable for the optical access network*.
+- [ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre and cable*.
+- [ITU-T G.653] Recommendation ITU-T G.653 (2010), *Characteristics of a dispersion-shifted single-mode optical fibre and cable*.
+- [ITU-T G.654] Recommendation ITU-T G.654 (2016), *Characteristics of a cut-off shifted single-mode optical fibre and cable*.
+- [ITU-T G.655] Recommendation ITU-T G.655 (2009), *Characteristics of a non-zero dispersion-shifted single-mode optical fibre and cable*.
+- [ITU-T G.656] Recommendation ITU-T G.656 (2010), *Characteristics of a fibre and cable with non-zero dispersion for wideband optical transport*.
+- [ITU-T G.657] Recommendation ITU-T G.657 (2016), *Characteristics of a bending loss insensitive single mode optical fibre and cable*.
+
+- [ITU-T L.100] Recommendation ITU-T L.100/L.10 (2015), *Optical fibre cables for duct and tunnel application.*
+- [ITU-T L.101] Recommendation ITU-T L.101/L.43 (2015), *Optical fibre cables for buried application.*
+- [ITU-T L.102] Recommendation ITU-T L.102/L.26 (2015), *Optical fibre cables for aerial application.*
+- [ITU-T L.103] Recommendation ITU-T L.103/L.59 (2016), *Optical fibre cables for indoor applications.*
+- [ITU-T L.162] Recommendation ITU-T L.162 (2016), *Microduct technology and its applications.*
+- [ITU-T L.400] Recommendation ITU-T L.400/L.12 (2008), *Optical fibre splices.*
+- [IEC 60189-1] IEC 60189-1 (2007), *Low-frequency cables and wires with PVC insulation and PVC sheath – Part 1: General test and measuring methods.*
+- [IEC 60793-1-1] IEC 60793-1-1 (2017), *Optical fibres – Part 1-1: Measurement methods and test procedures – General and guidance.*
+- [IEC 60793-1-20] IEC 60793-1-20 (2016), *Optical fibres – Part 1-20: Measurement methods and test procedures – Fibre geometry.*
+- [IEC 60793-1-21] IEC 60793-1-21 (2001), *Optical fibres – Part 1-21: Measurement methods and test procedures – Coating geometry.*
+- [IEC 60793-1-32] IEC 60793-1-32 (2010), *Optical fibres – Part 1-32: Measurement methods and test procedures – Coating strippability.*
+- [IEC 60793-1-53] IEC 60793-1-53 (2014), *Optical fibres – Part 1-53: Measurement methods and test procedures – Water immersion tests.*
+- [IEC 60793-2-10] IEC 60793-2-10 (2017), *Optical fibres – Part 2-10: Product specifications – Sectional specification for category A1 multimode fibres.*
+- [IEC 60794-1-1] IEC 60794-1-1 (2015), *Optical fibre cables – Part 1-1: Generic specification – General.*
+- [IEC 60794-1-2] IEC 60794-1-2 (2017), *Optical fibre cables – Part 1-2: Generic specification – Basic optical cable test procedures – General guidance.*
+- [IEC 60794-1-21] IEC 60794-1-21 (2015), *Optical fibre cables – Part 1-21: Generic specification – Basic optical cable test procedures – Mechanical tests methods.*
+- [IEC 60794-1-22] IEC 60794-1-22 (2012), *Optical fibre cables – Part 1-22: Generic specification – Basic optical cable test procedures – Environmental test methods.*
+- [IEC 60794-1-23] IEC 60794-1-23 (2012), *Optical fibre cables – Part 1-23: Generic specification – Basic optical cable test procedures – Cable element test methods.*
+- [IEC 60794-5] IEC 60794-5 (2014), *Optical fibre cables – Part 5: Sectional specification – Microduct cabling for installation by blowing.*
+- [IEC 60794-5-10] IEC 60794-5-10 (2014), *Optical fibre cables – Part 5-10: Family specification - Outdoor microduct optical fibre cables, microducts and protected microducts for installation by blowing.*
+- [IEC 60794-5-20] IEC 60794-5-20 (2014), *Optical fibre cables – Part 5-20: Family specification – Outdoor microduct fibre units, microducts and protected microducts for installation by blowing.*
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+For the purpose of this Recommendation, the definitions given in [ITU-T G.650.1] and [ITU-T G.651.1] apply.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 blowing duct:** There are three kinds of blowing ducts: outer protective duct, protected microduct and composite protected microduct/cable.
+
+**3.2.2 blown-in element:** A blown-in element consists of optical fibre(s), sheath and other materials and can be inserted into the microduct by continuous high-speed airflow force. Some of the characteristics of this element are described in clause 7.2.
+
+**3.2.3 composite protected microduct/cable:** A composite protected microduct/cable is a bundle containing both microducts and optical fibre cable. They are combined and surrounded by a tight or loose protective sheath, perhaps with another optional protective layer such as a moisture barrier.
+
+**3.2.4 microduct:** A small, flexible tube with enough wall thickness to provide the mechanical protection required by the application, with its outer and inner diameter defined according to the dimension and the condition of the existing duct and the diameter of the microcable.
+
+**3.2.5 microduct cable (also called microcable):** An optical fibre cable that is suitable for installation into a subducting microduct.
+
+**3.2.6 microduct fibre unit:** This is a group of fibres (with a count starting at 1) that can be installed in a microduct with the blowing technique.
+
+**3.2.7 micromodule:** This is a thin walled tubing unit. These flexible modules have bending radii similar to the unbundled fibre and are easy to strip without a tool for easy splice preparation and mid-span access. They have no shape memory and may be used directly in an enclosure up to the splicing tray. Water-blocking material may be contained in the micromodule, if required. See Figure 1.
+
+![Diagram of a micromodule cross-section showing thin and low modules wall tubing, fibre, and filling compound or dry filling solution.](af8f80bac7328747fbc93c2eb86f5be9_img.jpg)
+
+The diagram shows a cross-section of a micromodule. It consists of a thick blue outer ring representing the 'Thin and low modules wall tubing'. Inside this ring, there are several green circles representing 'Fibre' units. The space between the fibres is filled with a 'Filling compound or dry filling solution'. The label 'L.108(18)\_F01' is located at the bottom right of the diagram.
+
+Diagram of a micromodule cross-section showing thin and low modules wall tubing, fibre, and filling compound or dry filling solution.
+
+**Figure 1 – Example of primary coated fibres protected by micromodule**
+
+**3.2.8 protected microduct:** This kind of duct comprises a number of microducts that are loosely or tightly packed together and jacketed, in much the same way as an optical cable without the fibre.
+
+# **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|       |                                   |
+|-------|-----------------------------------|
+| FTTH  | Fibre To The Home                 |
+| HDPE  | High Density Polyethylene         |
+| LSZH  | Low Smoke Zero Halogen            |
+| OD/ID | Outer Diameter/Inner Diameter     |
+| OTDR  | Optical Time Domain Reflectometer |
+| PE    | Polyethylene                      |
+| PVC   | Polyvinyl Chloride                |
+
+# **5 Conventions**
+
+None.
+
+# **6 Environmental conditions**
+
+The required characteristics depend strongly on the environmental conditions at the location where the optical cables are installed. Therefore, it is important to know these conditions.
+
+## **6.1 Underground**
+
+### **6.1.1 Conduits and tunnels**
+
+The environmental conditions of conduits and tunnels are described in [ITU-T L.100].
+
+### **6.1.2 Direct buried**
+
+The environmental conditions for buried applications are described in [ITU-T L.101].
+
+## **6.2 Aerial**
+
+The environmental conditions for aerial applications are described in [ITU-T L.102].
+
+## **6.3 Indoor**
+
+The environmental conditions for indoor applications are described in [ITU-T L.103].
+
+# **7 Construction and characteristics of microduct system and cable elements**
+
+## **7.1 Fibre**
+
+### **7.1.1 Primary coated fibre**
+
+Primary coated fibres must comply with the relevant ITU-T G.65x-series Recommendations.
+
+### **7.1.2 Buffered fibre**
+
+When using a tight or semi-tight (loosely applied) buffer, the following characteristics are required:
+
+- A tight buffer should be easily removable over a length of 15 to 25 mm for fibre termination or splicing.
+- A semi-tight buffer should be easily removable over a length of 0.3 to 2 m for fibre termination or splicing, and without affecting the fibre coating.
+- With a tight buffer, the nominal diameter should be between 300 and 1000 µm, based on an agreement between the user and supplier. The tolerance should be  $\pm 50$  µm.
+
+- With a semi-tight buffer, the nominal diameter should be between 300 and 1400  $\mu\text{m}$ , based on an agreement between the user and supplier. The tolerance should be  $\pm 50 \mu\text{m}$ .
+
+## 7.2 Blown-in elements
+
+The key mechanical design issues related to the blown-in elements are diameter, weight, stiffness and elasticity, robustness, surface friction and element memory. Element memory is an attribute relating to the element's ability to return to its original shape, i.e., straight, after being bent. The relatively lower tensile force resulting from blowing in a microduct cable or microduct fibre unit generally results in a structure requiring lower tensile rating than that of ordinary optical fibre cables. Although the blown-in element is effectively pulled into the duct by an air stream during installation, there are circumstances under which compressive axial forces can occur, and hence the possibility of buckling the blown-in element. Buckling can cause jams in the duct and possible damage to the fibre being installed.
+
+Therefore, these elements must also be able to bend around corners, as typical installations will contain bends. Thus, the element bending stiffness must be sufficiently high to minimize the risk of buckling, but not so high as to prevent cornering during installation.
+
+Another key property of these elements is their surface characteristics. The goal is to maximize viscous air drag on these elements and minimize friction with the duct. Although these elements should be designed to minimize sliding friction inside the duct, its surface will contribute to drag.
+
+Regarding the fibre itself, any of the current ITU-T Recommendations may be considered, from [ITU-T G.651.1] to [ITU-T G.657].
+
+Different methods may be used to ensure correct fibre identification within the element (typically, by colouring fibres).
+
+Finally, the element must be robust to the presence of gases or liquids (typically, water) in the duct.
+
+### 7.2.1 Microduct cable
+
+Microduct cables, often called microcables, may consist of fibres, groupings of fibres, strength members, water blocking materials, sheaths and other appropriate materials. Microduct cable construction and performance is described by [IEC 60794-5-10].
+
+The attenuation of the installed cable at the operational wavelength(s) should not exceed the values of [IEC 60794-5-10] or as agreed between the customer and supplier.
+
+There should be no fibre splice in a delivery length unless otherwise agreed by the customer and supplier.
+
+It should be possible to identify each individual fibre throughout the length of the optical fibre microduct cable. Colour coding of fibres and units within the cable are common methods.
+
+Microduct cables typically have fibre counts ranging from 4 to 288 or more, with a typical outside diameter of 1.5 mm to 10.0 mm or even larger diameters. The units within may consist of single fibres, fibre groupings such as tubes, micromodules or ribbons.
+
+### 7.2.2 Microduct fibre unit
+
+These units differ from microduct optical fibre cables in that they provide less protection to the fibres that they contain. Microduct fibre unit construction and performance is described by [IEC 60794-5-20].
+
+Microduct fibre units do not utilize strength members as traditional fibre cables do, and therefore the stiffness and tensile strength of the entire element is achieved through the intrinsic stiffness of the fibre assemblage and the intrinsic tensile strength of the fibres themselves, as well as of the materials coating the fibres. Here the small cross-sectional geometry of the blown-in element plays a beneficial role in achieving a balance between flexibility and stiffness.
+
+The attenuation of an installed microduct fibre unit at the operational wavelength(s) should not exceed the values of [IEC 60794-5-20] or as agreed between the customer and supplier.
+
+There should be no fibre splice in a delivery length unless otherwise agreed between the customer and supplier.
+
+It should be possible to identify each individual fibre throughout the length of the microduct fibre unit. Colour coding and positional coding are common methods.
+
+Fibre units typically have fibre counts ranging from 1 to 24 fibres, and will typically have an outside diameter of between 1.0 mm and 3.2 mm. They may consist of single fibre, or an assembled bundle or a flat ribbon (made of two or four fibres). Bundles may be assembled using coating-like matrix, buffer material, binders or other methods meeting the design intent.
+
+## **7.3 Microducts**
+
+The microducts should be able to resist the pressure differences needed during installation with a blowing technique. They should be circular and uniform in cross-section throughout their length and the inner surface should have a low friction coefficient either by the material used (silicone, etc.) or having profiled ribbing. The inner and outer diameters should be specified.
+
+Microducts are intended for benign installation within ducts or as components within protected microducts as described in clause 7.4. In all cases it should be possible to identify each individual microduct throughout its length. Colour coding or marking are common methods for identification.
+
+Microducts can also be put into the interstices of ducts containing other cables.
+
+## **7.4 Protected microducts**
+
+Duct systems to install blown-in elements inside have been designed to optimize blowing distances and provide additional protection from the environment. Different kinds of protected microducts are considered, with alternative materials and properties, depending on the installation environment.
+
+For example, if rodent protection is needed, fibreglass yarn or corrugated laminated steel can be used in the outer duct.
+
+### **7.4.1 Outdoor protected microducts for duct installation**
+
+The outer duct of these microducts can be made of polyethylene, with an optional low friction anti-static inner surface. The surface may be ribbed or may be of a different material. For example, such a surface could be made of silicone rubber to reduce the friction or aluminium foil to deal with the presence of water.
+
+Inner duct counts may vary from 1 to more than 20 microducts. These inner microducts are typically coloured to facilitate identification.
+
+### **7.4.2 Outdoor protected microducts to be directly buried**
+
+Duct assemblies for direct burial should be more robust than those for duct installation. The outer duct of these microducts can be made of polyethylene: two sheaths of polyethylene (the outer one made of high density polyethylene), with a low friction anti-static inner surface. The surface may be ribbed or may be of a different material. For example, such a surface could be made of silicone to reduce the friction or aluminium foil to deal with the presence of water.
+
+Alternatively, they can consist of a bundle of microducts loosely pre-installed in a protective duct of the type commonly used as an empty protected duct.
+
+Inner microduct counts may vary from 1 to more than 20. These inner microducts are typically coloured to facilitate identification.
+
+### **7.4.3 Aerial protected microducts for outdoor installations**
+
+These microducts, can either be used singly or enclosed in a larger outer duct. Either type is usually made of polyethylene. The ducts that are suspended are often self-supporting with a typical installation span of up to 70 m. Different reinforcing elements or materials such as steel, fibreglass or aramid yarns should be used to improve the mechanical characteristics. These protected microducts may be lashed to aerial suspension elements in the same manner as outdoor optical fibre cables. Inner microduct counts may vary from 1 to more than 12. These inner microducts are typically coloured to facilitate identification.
+
+The suspension element can be metallic or dielectric, and the whole system should be waterproof.
+
+### **7.4.4 Indoor protected microducts**
+
+These microducts are usually made of halogen-free, flame-retardant material, with a low friction anti-static inner surface. Usually, fire safety is required (see clause 8.5). Inner microduct counts may vary from 1 to more than 15. These inner microducts typically have individual markings or colour coding for identification.
+
+## **7.5 Composite protected microduct/cable**
+
+Composite protected assemblies consist of microducts, optical fibre cables and protective sheaths, perhaps with some other optional protective layer such as a moisture barrier. The materials and configuration that can be used for microducts are described in clause 7.3. The requirements, configuration, characteristics and test methods of an optical fibre cable that is used for this unit are described in [ITU-T L.100], [ITU-T L.102], [ITU-T L.101] and [ITU-T L.103], and depend on the environment in which they are used.
+
+# **8 Test methods**
+
+The tests and performance requirements recommended herein should comply with the applicable requirements of [IEC 60794-1-1] and the relevant ITU-T G.65x-series Recommendations.
+
+## **8.1 Test methods for dimensions**
+
+[IEC 60793-1-20] and [IEC 60793-1-21] should be used for measuring fibre geometry parameters.
+
+[IEC 60189-1] should be used for measuring buffered fibres, tubes and cable diameters. This method can be employed to measure the thickness of a cable sheath, buffer tube, or similar.
+
+## **8.2 Test methods for cable elements**
+
+### **8.2.1 Tests applicable to optical fibres**
+
+This clause describes optical fibre test methods related to cabled fibre performance. Methods for testing the mechanical and optical characteristics of optical fibres are described in [ITU-T G.650.1], [ITU-T G.651.1] and [IEC 60793-1].
+
+#### **8.2.1.1 Coating strippability**
+
+[IEC 60793-1-32] should be used for measuring the strippability of primary or secondary fibre coatings.
+
+#### **8.2.1.2 Compatibility with filling material**
+
+When fibres come into contact with a filling material, the stability of the fibre coating and the filling material should be tested after accelerated ageing.
+
+The stability of the coating stripping force after ageing should be tested in accordance with method E5A of [IEC 60794-1-21].
+
+Dimensional stability and coating transmissivity should be examined by using a test method agreed upon between the manufacturer and the user.
+
+### 8.2.2 Tests applicable to tubes
+
+#### 8.2.2.1 Tube kink
+
+Method G7 of [IEC 60794-1-23] should be used for measuring the kink characteristics of a tube.
+
+## 8.3 Methods for testing mechanical characteristics
+
+The methods for testing the mechanical characteristics of each product are divided into two categories as shown in Table 1. This table is a general summary of the testing requirements of [IEC 60794-5-10] and [IEC 60794-5-20]. In the table, "recommended" means that a test should be performed. "Optional" means that a test will be performed if agreed between the manufacturer and the user. As regards the test methods, reference should be made to [IEC 60794-1-21], [IEC 60794-5] and [IEC 60794-5-10] for microduct cables or [IEC 60794-5-20] for fibre units.
+
+**Table 1 – Mechanical test methods applied for each product**
+
+|                            | <b>Protected microducts and microducts</b> | <b>Composite protected microduct/cable</b> | <b>Microduct fibre unit and microduct cable</b> |
+|----------------------------|--------------------------------------------|--------------------------------------------|-------------------------------------------------|
+| Tensile strength           | Recommended                                | Recommended                                | Recommended                                     |
+| Bending                    | Recommended                                | Recommended                                | Recommended                                     |
+| Crushing                   | Recommended                                | Recommended                                | Recommended                                     |
+| Torsion                    | Recommended                                | Recommended                                | Recommended                                     |
+| Impact                     | Recommended                                | Recommended                                | Recommended                                     |
+| Kink                       | Recommended                                | Recommended                                | Recommended                                     |
+| Repeated bending           | Recommended                                | Recommended                                | Recommended                                     |
+| Bending at low temperature | Optional                                   | Optional                                   | Optional                                        |
+
+NOTE – The mechanical test methods for protected microducts and microducts as well as the microducts in composite protected microduct/cable should be carried out as per [IEC 60794-5-10].
+
+### 8.3.1 Tensile strength
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+Measurements are made to examine the behaviour of the fibre attenuation and fibre strain as a function of the load on a cable or other elements during installation.
+
+The test should be carried out in accordance with method E1 of [IEC 60794-1-21].
+
+For cable, the amount of mechanical decoupling of the fibre and cable can be determined by measuring the fibre elongation with optical phase shift test equipment, together with cable elongation.
+
+This method may be non-destructive if the tension applied represents the operational values.
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### 8.3.2 Bending
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+The purpose of this test is to determine the ability of microduct cables to withstand bending around a pulley, as simulated by a test mandrel. The applicability to microduct fibre units should be as agreed between the manufacturer and the user.
+
+This test should be carried out in accordance with method E11A or E11B of [IEC 60794-1-21].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.3.3 Crushing**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+This test should be carried out in accordance with method E3A of [IEC 60794-1-21] (the plate/plate configuration).
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.3.4 Torsion**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+This test should be carried out in accordance with method E7 of [IEC 60794-1-21].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.3.5 Impact**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+This test should be carried out in accordance with method E4 of [IEC 60794-1-21].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.3.6 Kink**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+This test should be carried out in accordance with method E10 of [IEC 60794-1-21].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.3.7 Repeated bending**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+This test should be carried out in accordance with method E6 of [IEC 60794-1-21].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.3.8 Bending at low temperature**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+This test should be carried out in accordance with method E11A or E11B of [IEC 60794-1-21].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units and at the minimum installation temperature, as  $T_{A1}$ .
+
+## **8.4 Test methods for environmental characteristics**
+
+This clause recommends appropriate tests and test methods for verifying the environmental characteristics of optical fibre cables.
+
+### **8.4.1 Temperature cycling**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+Testing involves temperature cycling to determine the stability of the attenuation of a microduct element in the presence of ambient temperature changes, which may occur during storage, transportation, installation and operation.
+
+This test should be carried out in accordance with method F1 of [IEC 60794-1-22].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.4.2 Ageing**
+
+This test method applies to microduct cables, microduct fibre units installed under all environmental conditions.
+
+Testing involves extended high temperature exposure after temperature cycling to determine the stability of the attenuation of a cable after simulated ageing.
+
+This test should be carried out in accordance with method F9 of [IEC 60794-1-22].
+
+The test conditions should be identical to those of [IEC 60794-5-10] for microduct cables and [IEC 60794-5-20] for microduct fibre units.
+
+### **8.4.3 Water penetration for microduct cables**
+
+This test method applies to microduct cables installed under all environmental conditions.
+
+Testing involves exposure of a cable specimen to a water head at one end to evaluate the ability of the microduct cable to inhibit the longitudinal flow of water.
+
+This test should be carried out in accordance with method F5B or F5C, as appropriate to the cable design, of [IEC 60794-1-22].
+
+The test conditions should be identical to those of [IEC 60794-5-10].
+
+### **8.4.4 Water immersion for microduct fibre units**
+
+This test method applies to microduct fibre units installed under all environmental conditions.
+
+Testing involves soaking a microduct fibre unit specimen in water (or other fluid, as agreed) to evaluate the integrity of the fibre unit after such exposure.
+
+This test should be carried out in accordance with [IEC 60793-1-53].
+
+The test conditions should be identical to those of [IEC 60794-5-20].
+
+### **8.4.5 UV exposure testing**
+
+These tests apply to any elements of this Recommendation installed so that they are exposed to ultraviolet (UV) radiation. Elements for indoor applications may be exposed to UV radiation from fluorescent lights. Elements for outdoor application may be exposed to UV radiation from sunlight. UV exposure can cause degradation of the outer surface and of the material characteristics of the exposed element.
+
+Testing differs for indoor and outdoor exposure because of the different spectrums and intensity of UV radiation, and requires different test methods and attribute values. These differences are specifically addressed in the standard test method for cable UV resistance.
+
+Testing should be carried out in accordance with method F14 of [IEC 60794-1-22].
+
+The exposed outer material of the element should retain at least 80% of the elongation and tensile strength before exposure.
+
+## **8.5 Test methods for fire safety**
+
+The user is advised that local fire codes are predominant in this subject area. [IEC/TR 62222] provides guidance and recommendations for the requirements and test methods for the fire performance of communication cables when installed in buildings. The recommendations relate to typical applications and installation practices, and an assessment of the fire hazards presented. Account is also taken of applicable legislation and regulation.
+
+[IEC/TR 62222] references several IEC fire performance test methods and also other test methods that may be required by local or national legislation and regulation. The tests to be applied, and the requirements, should be agreed between the manufacturer and the user taking into account the fire hazard presented by the end use application in which the cable is intended to be used.
+
+## **8.6 Test methods for installation performance**
+
+This clause recommends appropriate tests and test methods for verifying that a microduct cable and microduct fibre unit can be installed in a microduct in the manner intended. The microduct installation test should refer to methods E23 and E24 in [IEC 60794-1-21].
+
+# Appendix I
+
+# Chinese experience
+
+(This appendix does not form an integral part of this Recommendation.)
+
+## I.1 Product types of microducts
+
+Product types of microduct include outer protective ducts, microducts, microduct bundles, protected microducts, composite protected microduct/cable, etc.
+
+Their main specifications are shown in Table I.1.
+
+**Table I.1 – Main specifications and arrangements of microduct**
+
+| Duct type                           |                           |          | Example of maximum capacity of sub-ducts or microcables                                         | Layout purpose                                                                            |
+|-------------------------------------|---------------------------|----------|-------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------|
+| Duct type                           | Outer/inner diameter (mm) | Material |                                                                                                 |                                                                                           |
+| Underground telecommunication ducts | 110/100                   | PVC PE   | 3 × 40/33 outer protective ducts, 4 × 34/28 outer protective ducts                              | Backbone conduit, or conduit from telecom central office.                                 |
+|                                     | 100/90                    | PVC PE   | 2 × 40/33 outer protective ducts, 3 × 34/28 or 32/26 outer protective ducts                     | Backbone conduit.                                                                         |
+|                                     | 75/65                     | PVC PE   | 2 × 32/26 outer protective ducts                                                                | Branching conduit to distribution point, or feeder conduit to a great number of users.    |
+| Outer protective ducts              | 63/54                     | HDPE     | 10 × 10/8 microducts, 20 × 7/5 microducts                                                       | Placed inside underground telecommunication ducts/ rainwater pipelines, or used directly. |
+|                                     | 50/41                     | HDPE     | 7 × 10/8 microducts, 14 × 7/5 microducts                                                        |                                                                                           |
+|                                     | 46/38                     | HDPE     | 6 × 10/8 microducts, 12 × 7/5 microducts                                                        |                                                                                           |
+|                                     | 40/33                     | HDPE     | 5 × 10/8 microducts, 7 × 8/6 microducts, 10 × 7/5 microducts, 4 groups of 4/3 microduct bundles |                                                                                           |
+|                                     | 34/28                     | HDPE     | 3 × 10/8 microducts, 7 × 7/5 microducts                                                         |                                                                                           |
+|                                     | 32/28                     | HDPE     | 3 × 10/8 microducts, 7 × 7/5 microducts                                                         |                                                                                           |
+|                                     | 32/26                     | HDPE     | 3 × 10/8 microducts, 6 × 7/5 microducts                                                         |                                                                                           |
+
+**Table I.1 – Main specifications and arrangements of microduct**
+
+| Duct type         |                                                  |          | Example of maximum capacity of sub-ducts or microcables                                                                                                                                                                         | Layout purpose                                                                            |  |
+|-------------------|--------------------------------------------------|----------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------|--|
+| Duct type         | Outer/inner diameter (mm)                        | Material |                                                                                                                                                                                                                                 |                                                                                           |  |
+| Microducts        | 20.0/16.0                                        | HDPE     |                                                                                                                                                                                                                                 | Placed inside the outer protective ducts.                                                 |  |
+|                   | 16.0/14                                          | HDPE     | Could accommodate the microduct cable, and the ratio of the cross-sectional area of the microduct cable to the inner aperture area of the microduct is generally not more than 60%.                                             |                                                                                           |  |
+|                   | 14.0/10.0**                                      | HDPE     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 12.0/10.0*                                       | HDPE     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 10.0/8.0*                                        | HDPE     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 8.0/6.0                                          | HDPE     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 7.0/5.5*                                         | HDPE     | Could accommodate microduct cable or microduct fibre unit, and the ratio of the cross-sectional area of the microduct cable or microduct fibre unit to the inner aperture area of the microduct is generally not more than 60%. |                                                                                           |  |
+|                   | 5.0/3.5*                                         | HDPE     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 4.0/3.0                                          | LSZH     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 3.5/2.5                                          | LSZH     |                                                                                                                                                                                                                                 |                                                                                           |  |
+|                   | 3.0/2.1                                          | LSZH     |                                                                                                                                                                                                                                 |                                                                                           |  |
+| Microduct bundles | Main types are 1, 2, 4, 7, 12, 19, 24 apertures. |          |                                                                                                                                                                                                                                 | Placed inside underground telecommunication ducts/ rainwater pipelines, or used directly. |  |
+
+NOTE 1 – The microducts noted with \* are often used and \*\* are ducts with larger wall thickness.  
+NOTE 2 – The choice of duct diameter should be based on the most commonly used specifications, reducing the size of duct, and improving the air-blowing performance.  
+NOTE 3 – If necessary, the ratio of the cross-sectional area of the microduct cable to the inner aperture area of the microduct can be expanded to 70%. In this case, the blowing distance may decline.
+
+## I.2 Microduct inner clearance verification
+
+**Test method:** As shown in Figure I.1, fix the microduct on a plate to make it remain horizontal, and then put the experimental object into the sample to see if it could reach the other end of the microduct.
+
+NOTE 1 – If the microduct is flat enough, the plate is not required.
+
+**Sample length:** A short segment of the microduct is used, usually 2 m length.
+
+NOTE 2 – If longer microduct is tested, refer to method E23 of [IEC 60794-1-21].
+
+**Test apparatus:** a) An experimental object, either a small steel ball or a short segment of microduct cable or microduct fibre unit to be installed (for example, 100 mm long). The outer diameter of the experimental object should not be less than 85% of the nominal inner diameter of the microduct under test. b) A piece of flat plate; this helps to make the microduct remain flat.
+
+**Performance guidance:** The experimental object should pass through the microduct.
+
+![Figure I.1: Test set-up for microduct inner clearance verification. The diagram shows a cross-section of a microduct. On the left, a 'Plate' is shown with a 'Steel ball' (represented by a dashed circle) inside the microduct. The 'Sample' (microduct) is held in place by two 'Clamp' units. The label 'L.108(18)_FI.1' is in the bottom right corner.](cd91fd97c6e4da454b42f4fde13f7e44_img.jpg)
+
+Figure I.1: Test set-up for microduct inner clearance verification. The diagram shows a cross-section of a microduct. On the left, a 'Plate' is shown with a 'Steel ball' (represented by a dashed circle) inside the microduct. The 'Sample' (microduct) is held in place by two 'Clamp' units. The label 'L.108(18)\_FI.1' is in the bottom right corner.
+
+**Figure I.1 – Test set-up for microduct inner clearance verification**
+
+## **I.3 Blowing performance test for microcables or fibre units in microduct**
+
+### **I.3.1 Method A: Blowing test through microduct on drum**
+
+**Test method:** as shown in Figure I.2.
+
+**Sample length:** not less than 500 m.
+
+**Microduct drum diameter:** to be 1000 mm for microcables; to be 500 mm for fibre units.
+
+**Microduct diameter when sample is a microcable:** To be determined according to the ratio of the cross-sectional area of the microcable to the inner aperture area of the microduct. Generally, 45% to 65% are specified as reasonable ratios. (Lower limit is possible)
+
+**Microduct diameter when sample is fibre unit:** to be determined according to the dimension of the fibre unit and the maximum blowing force that it can support. Generally, the reasonable microduct diameter range is from 2.5 mm to 6.0 mm.
+
+**Blowing pressure:** generally, 15 bar max. for microduct cables and 10 bar max. for microduct fibre units. Lower pressure may be agreed upon between the customer and supplier.
+
+**Relative humidity of air in microduct:** 40% to 60%.
+
+**Number of tests:** 3 times.
+
+**Performance guidance:** In order to evaluate the blowing performance of blowing products, in the test process the installation length, installation speed and blowing pressure should be recorded corresponding to installation time. Generally speaking, as for microduct cables, the average installation speed should be not less than 25 m/min, installation length in 20 minutes should be not less than 500 m. As for fibre units, the average installation speed should be not less than 20 m/min, installation length in 25 minutes should be not less than 500 m.
+
+![Figure I.2: Test set-up for blowing performance on drum. The diagram shows a 'Microduct cable or microduct fibre unit' being blown from a 'Blowing tool' into a '500 m - microduct' drum. The label 'L.108(18)_FI.2' is in the bottom right corner.](a7b0ce8ddbb18a80bb6f57334023059d_img.jpg)
+
+Figure I.2: Test set-up for blowing performance on drum. The diagram shows a 'Microduct cable or microduct fibre unit' being blown from a 'Blowing tool' into a '500 m - microduct' drum. The label 'L.108(18)\_FI.2' is in the bottom right corner.
+
+**Figure I.2 – Test set-up for blowing performance on drum**
+
+### **I.3.2 Method B: Blowing test through microduct on field (simulated)**
+
+**Test method:** Besides method E24 of [IEC 60794-1-21], the microduct can be laid out according to one of a), b) and c) in Figure I.3. Sufficient access to both ends of the microduct should be provided. The microduct should then be positioned for the duration of the tests. Air should then be blown into the microduct through the blowing head for 20 minutes to condition the reference test route. Then the microduct cable or microduct fibre unit should be installed into the microduct at up to the maximum
+
+speed specified, until the microduct cable or microduct fibre unit is blown out of the other end of the microduct.
+
+**Sample length:** not less than 1000 m for microduct cables; 500 m for microduct fibre units.
+
+**Microduct diameter when sample is a microduct cable:** to be determined according to the ratio of the cross-sectional area of the microduct cable to the inner aperture area of the microduct. Generally, 45% to 65% are specified as reasonable ratios (lower limit is possible).
+
+**Microduct diameter when sample is a microduct fibre unit:** To be determined according to the dimensions of the microduct fibre unit and the maximum blowing force that it can support. Generally, reasonable values for the microduct diameter are 2.5 mm to 6.0 mm.
+
+**Blowing pressure:** Generally, 15 bar max. for microduct cables and 10 bar max. for fibre units. Lower pressure may be agreed upon between the user and supplier.
+
+**Relative humidity of air in microduct:** 40% to 60% (only relevant for microduct fibre units).
+
+**Number of tests:** 3 times.
+
+**Performance guidance:** In order to evaluate the blowing performance of blowing products, in the test process the installation length, installation speed and blowing pressure should be recorded corresponding to installation time. Generally speaking, for microduct cables, the average installation speed should be not less than 35 m/min, installation length in 30 minutes should be not less than 1000 m. For microduct fibre units, the average installation speed should be not less than 25 m/min, installation length in 20 minutes should be not less than 500 m.
+
+![Figure I.3 shows three test routes for blowing performance in the field (simulated). Route A is a straight line with a total length of 48.5 m ± 2 m and a diameter of 3 m ± 0.4 m. Route B is a square loop with side lengths of 25.5 m ± 1.0 m and a corner radius of 0.8 m ± 0.1 m. Route C is a figure-eight loop with a total length of 25 m and a height of 8.5 m, starting at 'Start' and ending at 'End'.](75e4b78ee25f885d73120e3066a5253e_img.jpg)
+
+a) Route A
+
+b) Route B
+
+c) Route C
+
+L.108(18)\_FI.3
+
+Figure I.3 shows three test routes for blowing performance in the field (simulated). Route A is a straight line with a total length of 48.5 m ± 2 m and a diameter of 3 m ± 0.4 m. Route B is a square loop with side lengths of 25.5 m ± 1.0 m and a corner radius of 0.8 m ± 0.1 m. Route C is a figure-eight loop with a total length of 25 m and a height of 8.5 m, starting at 'Start' and ending at 'End'.
+
+**Figure I.3 – Test set-up for blowing performance in the field (simulated)**
+
+## I.4 Layout location selection for microduct
+
+The best layout location should be selected according to Table I.2, taking local conditions into account.
+
+**Table I.2 – The priority of layout location selection for microduct**
+
+| Sequence number | Layout region    | Layout location for microduct                                                                                                                                                                                                                      |
+|-----------------|------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 1               | Super highway    | 1) Central reservation (median strip)<br>2) Road shoulder<br>3) Inside safety guardrail<br>4) Roadside ditch                                                                                                                                       |
+| 2               | Ordinary highway | 1) Invariable highway: road shoulder, the belt between the roadside ditch and the edge of highway, the roadside ditch<br>2) Variable highway: within 200 m of the highway; avoiding the influence of inclines, changes in direction or width, etc. |
+| 3               | City street      | 1) Footway footpath (sidewalk)<br>2) Slow lane<br>3) Fast lane                                                                                                                                                                                     |
+| 4               | Other region     | 1) Suitable topography and consistent geology<br>2) Convenient access for blowing machines                                                                                                                                                         |
+
+### Burying depth
+
+The burying depth for protected microduct should be determined according to the characteristics of the soil and environment around layout regions. The main specifications are shown in Table I.3.
+
+**Table I.3 – Guidance on burying depth for protected microduct**
+
+| Number | Characteristics of soil and layout regions                                 | Burying depth (m)                           |
+|--------|----------------------------------------------------------------------------|---------------------------------------------|
+| 1      | Ordinary soil, hard soil                                                   | $\geq 1.0$                                  |
+| 2      | Half stone-like soil (for example stonebrash and efflorescent stone, etc.) | $\geq 0.8$                                  |
+| 3      | Full stone-like soil and quicksand                                         | $\geq 0.6$                                  |
+| 4      | Suburb, village and small town                                             | $\geq 1.0$                                  |
+| 5      | City street                                                                | $\geq 0.8$                                  |
+| 6      | Through railroad or highway from underside                                 | $\geq 1.0$ (from roadbed)                   |
+| 7      | Central reservation (median strip) and road shoulder of highway            | $\geq 0.7$ (pavement) and $\geq 0.8$ (road) |
+| 8      | Groove, ditch and pond                                                     | $\geq 1.0$                                  |
+
+# Appendix II
+
+# Chinese experience on effects of freezing conditions on microduct air-blown cables
+
+(This appendix does not form an integral part of this Recommendation.)
+
+## II.1 Introduction
+
+With the development of fibre to the home (FTTH) network construction, microduct air-blown cables are more frequently used, even in some cold regions. In this case, the water permeated into the microduct will be frozen under such low temperatures. In order to study the effects of freezing conditions on the transmission performance of optical fibres, freezing tests to simulate the cold climate with the aid of temperature cycling chambers have been designed. During the tests, the attenuation change of the fibres is monitored and also the appearance of the cable is checked.
+
+## II.2 Freezing test
+
+#### II.2.1 Test details
+
+Microduct air-blown cable: stranded loose tube structure containing 96 G.652D fibres with an outer diameter of 6.1 mm.
+
+Microduct: HDPE duct with OD/ID: 10/8 mm.
+
+Cycles: 2.
+
+#### II.2.2 Impact on fibre attenuation with water frozen in microducts
+
+A 1.8 km long microduct air-blown cable and an 80 m long microduct are used.
+
+First, soak the 80 m long microduct (with cable inside) in water for 24 hours to fill the duct completely with water. Seal the duct with end caps. Then take the cable as well as the duct out and put them into the temperature cycling chamber. Then record the attenuation of each fibre at room temperature (23°C).
+
+##### Temperature cycling programme
+
+1. Lower the temperature from 23°C to 3°C within 30 minutes and hold this temperature for 8 hours. Record the attenuation of each fibre.
+2. Then lower the temperature to -40°C within 30 minutes and hold it until the water is completely frozen and the ice temperature is -10°C or lower (by using a temperature monitoring device).
+3. Raise the temperature to -2°C and hold this temperature for 1 hour. Record the attenuation of each fibre.
+4. Raise the temperature to 65°C. Maintain the temperature until the water reaches 15°C. Then, return the temperature to 23°C and hold the temperature until the water reaches 23°C±5°C. Record the attenuation of each fibre.
+
+##### Results and analysis
+
+1. During the test, attenuation changes of all fibres are really small. The largest attenuation values at -2°C are shown in Figure II.1, at 1310 nm and 1550 nm wavelengths respectively.
+
+![Two OTDR graphs showing fibre attenuation at -2°C. The left graph is for 1550 nm with an attenuation of 0.186 dB/Km. The right graph is for 1310 nm with an attenuation of 0.324 dB/Km. Both graphs show a smooth curve with a single event at approximately 10 km.](9ce50bc10864dc86e1cdee4be08f1897_img.jpg)
+
+Figure II.1 displays two OTDR graphs for fibre attenuation at  $-2^{\circ}\text{C}$ . The left graph shows the attenuation at 1550 nm, which is 0.186 dB/Km. The right graph shows the attenuation at 1310 nm, which is 0.324 dB/Km. Both graphs display a smooth curve with a single event at approximately 10 km.
+
+L.108(18)\_FII.1
+
+Two OTDR graphs showing fibre attenuation at -2°C. The left graph is for 1550 nm with an attenuation of 0.186 dB/Km. The right graph is for 1310 nm with an attenuation of 0.324 dB/Km. Both graphs show a smooth curve with a single event at approximately 10 km.
+
+**Figure II.1 – OTDR graphs of the fibre with largest attenuation values at  $-2^{\circ}\text{C}$**
+
+- Considering the microduct is rarely full of water and the actual temperature change rate is much slower than that in the experiment, the impact of ice in microducts on air-blown cables can be regarded as insignificant.
+
+##### **Additional test (for extreme weather conditions)**
+
+When considering extreme cold weather conditions, the temperature cycling programme is changed and the above test repeated.
+
+##### **Temperature programme (for extreme weather conditions)**
+
+- Lower the temperature from  $23^{\circ}\text{C}$  to  $-40^{\circ}\text{C}$  within 30 minutes and hold this temperature for 12 hours. Perform attenuation measurement.
+- Raise the temperature to  $65^{\circ}\text{C}$  within 30 minutes and hold it for 12 hours. Perform attenuation measurement.
+- Return the temperature to  $23^{\circ}\text{C}$  within 30 minutes and hold this temperature for 12 hours. Perform attenuation measurement.
+
+##### **Results and analysis (for extreme weather conditions)**
+
+- During the test, attenuation changes of all fibres are really small and the optical time domain reflectometer (OTDR) curves are very smooth. The test results at  $-40^{\circ}\text{C}$  should be the worst. Therefore, the largest attenuation values at  $-40^{\circ}\text{C}$  are displayed in Figure II.2, at 1310 nm and 1550 nm wavelengths respectively.
+
+![Two OTDR graphs showing fibre attenuation at -40°C. The left graph is for 1550 nm with an attenuation of 0.190 dB/Km. The right graph is for 1310 nm with an attenuation of 0.328 dB/Km. Both graphs show a smooth curve with a single event at approximately 10 km.](367ee68d9b8e16d27f4271a3c5c8ed18_img.jpg)
+
+Figure II.2 displays two OTDR graphs for fibre attenuation at  $-40^{\circ}\text{C}$ . The left graph shows the attenuation at 1550 nm, which is 0.190 dB/Km. The right graph shows the attenuation at 1310 nm, which is 0.328 dB/Km. Both graphs display a smooth curve with a single event at approximately 10 km.
+
+L.108(18)\_FII.2
+
+Two OTDR graphs showing fibre attenuation at -40°C. The left graph is for 1550 nm with an attenuation of 0.190 dB/Km. The right graph is for 1310 nm with an attenuation of 0.328 dB/Km. Both graphs show a smooth curve with a single event at approximately 10 km.
+
+**Figure II.2 – OTDR graphs of the fibre with largest attenuation values at  $-40^{\circ}\text{C}$**
+
+- The largest fibre attenuation values in each loose tube at different temperature points during the above test and the additional test are shown in Figure II.3, at 1310 nm and 1550 nm wavelengths respectively. During this extreme weather condition test, attenuation changes of all fibres are really small.
+
+![Figure II.3: Two line graphs showing fibre attenuation values at different temperatures for 1550 nm and 1310 nm wavelengths. The left graph for 1550 nm shows attenuation values between 0.175 and 0.20 dB/km. The right graph for 1310 nm shows attenuation values between 0.316 and 0.328 dB/km. Both graphs plot data for nine fibre types (B, OR, GR, BR, GREY, W, R, BL) across seven temperature points (23, 3, -2, 23, -40, 70, 20 °C).](1d3994bfe548ae7545d57df703e32a02_img.jpg)
+
+**1550 nm**
+
+| Temperature (°C) | B     | OR    | GR    | BR    | GREY  | W     | R     | BL    |
+|------------------|-------|-------|-------|-------|-------|-------|-------|-------|
+| 23               | 0.186 | 0.191 | 0.191 | 0.191 | 0.190 | 0.188 | 0.185 | 0.186 |
+| 3                | 0.188 | 0.193 | 0.193 | 0.193 | 0.192 | 0.189 | 0.187 | 0.188 |
+| -2               | 0.188 | 0.195 | 0.195 | 0.195 | 0.194 | 0.190 | 0.185 | 0.188 |
+| 23               | 0.188 | 0.191 | 0.191 | 0.191 | 0.190 | 0.188 | 0.185 | 0.188 |
+| -40              | 0.192 | 0.198 | 0.198 | 0.198 | 0.197 | 0.194 | 0.192 | 0.192 |
+| 70               | 0.186 | 0.194 | 0.194 | 0.194 | 0.193 | 0.187 | 0.193 | 0.186 |
+| 20               | 0.186 | 0.191 | 0.191 | 0.191 | 0.190 | 0.188 | 0.185 | 0.186 |
+
+**1310 nm**
+
+| Temperature (°C) | B     | OR    | GR    | BR    | GREY  | W     | R     | BL    |
+|------------------|-------|-------|-------|-------|-------|-------|-------|-------|
+| 23               | 0.320 | 0.325 | 0.323 | 0.323 | 0.321 | 0.322 | 0.320 | 0.320 |
+| 3                | 0.321 | 0.325 | 0.324 | 0.324 | 0.322 | 0.322 | 0.320 | 0.321 |
+| -2               | 0.324 | 0.326 | 0.324 | 0.324 | 0.323 | 0.323 | 0.321 | 0.324 |
+| 23               | 0.323 | 0.325 | 0.323 | 0.323 | 0.322 | 0.322 | 0.320 | 0.323 |
+| -40              | 0.324 | 0.326 | 0.325 | 0.325 | 0.324 | 0.323 | 0.322 | 0.324 |
+| 70               | 0.324 | 0.325 | 0.323 | 0.323 | 0.322 | 0.320 | 0.321 | 0.324 |
+| 20               | 0.322 | 0.324 | 0.322 | 0.322 | 0.321 | 0.322 | 0.320 | 0.322 |
+
+Figure II.3: Two line graphs showing fibre attenuation values at different temperatures for 1550 nm and 1310 nm wavelengths. The left graph for 1550 nm shows attenuation values between 0.175 and 0.20 dB/km. The right graph for 1310 nm shows attenuation values between 0.316 and 0.328 dB/km. Both graphs plot data for nine fibre types (B, OR, GR, BR, GREY, W, R, BL) across seven temperature points (23, 3, -2, 23, -40, 70, 20 °C).
+
+**Figure II.3 – Largest attenuation values in each loose tube at different temperature points**
+
+- Until all the above tests have been finished, the cable is blown out of the duct by compressed air. It shows that the blowing performance of the cable is still good and no visual damage to the cable sheath has been found.
+
+#### II.2.3 Impact on fibre attenuation with water frozen around end caps
+
+A 1.8 km long microduct air-blown cable and 6 m long microduct are used in this test. Move the microduct to the middle of the cable and record the distance from the test end to the microduct.
+
+First, seal one end of the microduct with an end cap and fill water into the duct till it is full of water. Then seal the other end of the duct with another end cap and keep the two end caps at the same height.
+
+Before the experiment, record the attenuation of each fibre. Then put the cable into the temperature cycling chamber and set the temperature programme as below:
+
+- Lower the temperature from 23°C to -40°C within 30 minutes and hold this temperature for 12 hours. Perform attenuation measurement.
+- Raise the temperature to 70°C within 30 minutes and hold it for 12 hours. Perform attenuation measurement.
+- Return temperature to 23°C within 30 minutes and hold this temperature for 12 hours. Perform attenuation measurement.
+
+##### Results and analysis
+
+- Check the end caps at -40°C. Some ice can be found around them. Therefore, the situation where water freezes around end caps, as shown in Figure II.4, is successfully simulated.
+
+![A close-up photograph of a hand pointing to a cable end cap. The cap is a small, cylindrical component with a blue top and a red base. The cable itself is light grey. The background is dark and appears to be an indoor setting with a door or panel.](7b517f15a2d307945bd78e30c13a75bd_img.jpg)
+
+A close-up photograph of a hand pointing to a cable end cap. The cap is a small, cylindrical component with a blue top and a red base. The cable itself is light grey. The background is dark and appears to be an indoor setting with a door or panel.
+
+L.108(18)\_FII.4
+
+**Figure II.4 – Water frozen around end caps**
+
+2. Note the positions where the end caps are located on the attenuation curve during measurement. The OTDR curves are very smooth.
+3. During the test, attenuation changes of all fibres are really small and no visual damage to the cable sheath has been found.
+
+## **II.3 Conclusion**
+
+When microduct air-blown cables are used in cold areas, the influence of freezing conditions on optical fibre transmission should be taken into consideration. In order to study this subject, two experiments are designed to evaluate this influence. Based on the test results, it can be concluded that the effects of frozen water on microduct air-blown cables are insignificant. However, the long-term effects during a cable's lifetime should be also considered. Thus, protective measures to avoid the penetration of water into microducts should not be ignored.
+
+# Bibliography
+
+[b-ITU-T Technical Report] ITU-T Technical Report (2015), *Optical fibres, cables and systems*.
+
+
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

marked/L/T-REC-L.109.1-202211-I_PDF-E/raw.md

@@ -0,0 +1,652 @@
+
+
+# Recommendation **ITU-T L.109.1 (11/2022)**
+
+SERIES L: Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant
+
+Optical fibre cables – Cable structure and characteristics
+
+---
+
+## **Type II optical/electrical hybrid cables for access points and other terminal equipment**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a blue circular emblem with a stylized globe and the letters 'ITU' in white.
+
+ITU logo
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+## ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT
+
+|                                                        |                    |
+|--------------------------------------------------------|--------------------|
+| OPTICAL FIBRE CABLES                                   |                    |
+| <b>Cable structure and characteristics</b>             | <b>L.100–L.124</b> |
+| Cable evaluation                                       | L.125–L.149        |
+| Guidance and installation technique                    | L.150–L.199        |
+| OPTICAL INFRASTRUCTURES                                |                    |
+| Infrastructure including node elements (except cables) | L.200–L.249        |
+| General aspects and network design                     | L.250–L.299        |
+| MAINTENANCE AND OPERATION                              |                    |
+| Optical fibre cable maintenance                        | L.300–L.329        |
+| Infrastructure maintenance                             | L.330–L.349        |
+| Operation support and infrastructure management        | L.350–L.379        |
+| Disaster management                                    | L.380–L.399        |
+| PASSIVE OPTICAL DEVICES                                | L.400–L.429        |
+| MARINIZED TERRESTRIAL CABLES                           | L.430–L.449        |
+| E-WASTE AND CIRCULAR ECONOMY                           | L.1000–L.1199      |
+| POWER FEEDING AND ENERGY STORAGE                       | L.1200–L.1299      |
+| ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES | L.1300–L.1399      |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES  | L.1400–L.1499      |
+| ADAPTATION TO CLIMATE CHANGE                           | L.1500–L.1599      |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES        | L.1600–L.1699      |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                    | L.1700–L.1799      |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.109.1
+
+## Type II optical/electrical hybrid cables for access points and other terminal equipment
+
+## Summary
+
+Recommendation ITU-T L.109.1 explains the type II optical/electrical hybrid cable (OEHC) in which a copper pair is used for power delivery (not for telecommunications) and an optical fibre can support data transmission up to and beyond 1 Gbit/s. The current application scenarios for remote powering and data transmission of access points and other equipment require a type of hybrid cable that has a small footprint, is lightweight, and is convenient for installation.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T L.109.1  | 2022-11-13 | 15          | <a href="http://handle.itu.int/11.1002/1000/15122">11.1002/1000/15122</a> |
+
+## Keywords
+
+Access point/terminals, type II optical/electrical hybrid cables.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2023
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                     | Page |
+|---------------------------------------------------------------------|------|
+| 1 Scope .....                                                       | 1    |
+| 2 References.....                                                   | 1    |
+| 3 Definitions .....                                                 | 3    |
+| 4 Abbreviations and acronyms .....                                  | 3    |
+| 5 Conventions .....                                                 | 3    |
+| 6 Type II optical/electrical hybrid cable application scenario..... | 3    |
+| 7 OEHC construction.....                                            | 5    |
+| 7.1 General .....                                                   | 5    |
+| 7.2 Optical fibre element .....                                     | 6    |
+| 7.3 Optical fibre coating and requirements .....                    | 6    |
+| 7.4 Conductor requirements .....                                    | 6    |
+| 7.5 Strength member .....                                           | 6    |
+| 7.6 Yarn (optional) .....                                           | 7    |
+| 7.7 Tape (optional) .....                                           | 7    |
+| 7.8 Ripcord (optional) .....                                        | 7    |
+| 7.9 Inner sheath .....                                              | 7    |
+| 7.10 Screen or shield (optional).....                               | 7    |
+| 7.11 Moisture barrier (optional) .....                              | 7    |
+| 7.12 Armouring (optional).....                                      | 8    |
+| 7.13 Outer sheath.....                                              | 8    |
+| 7.14 Sheath marking.....                                            | 8    |
+| 7.15 Cable structure.....                                           | 8    |
+| 8 Rated values and characteristics .....                            | 9    |
+| 8.1 Minimum bending radius for installation .....                   | 9    |
+| 8.2 Temperature range.....                                          | 9    |
+| 8.3 Rated voltages .....                                            | 10   |
+| 9 Performance requirements and test methods .....                   | 10   |
+| 9.1 Optical requirements .....                                      | 10   |
+| 9.2 Electrical requirements.....                                    | 10   |
+| 9.3 Mechanical requirements.....                                    | 11   |
+| Appendix I – Chinese experience .....                               | 13   |
+| I.1 Introduction .....                                              | 13   |
+| I.2 Cable structure.....                                            | 13   |
+| I.3 Application network .....                                       | 14   |
+| Bibliography.....                                                   | 15   |
+
+
+
+# Recommendation ITU-T L.109.1
+
+## Type II optical/electrical hybrid cables for access points and other terminal equipment
+
+# 1 Scope
+
+This Recommendation explains the requirements for type II optical/electrical hybrid cables (OEHC) for access points (APs) and other terminal equipment that can support data transmission up to and beyond 1 Gbit/s that require remote powering. As classified in [ITU-T L.109], a copper pair in the type II OEHC is not used for telecommunication but for power delivery.
+
+This Recommendation:
+
+- explains the cables that may be installed outdoors, indoors and indoors/outdoors;
+- describes the characteristics of type II OEHC;
+- provides suggestions for cable construction with optical fibres that comply with [ITU-T G.652], [ITU-T G.657] and [IEC 60793-2-10];
+- suggests acceptance criteria and requirements in test methods for type II OEHC; and
+- suggests installation requirements for type II OEHC.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [ITU-T G.650.1] Recommendation ITU-T G.650.1 (2020), *Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable*.
+- [ITU-T G.650.2] Recommendation ITU-T G.650.2 (2015), *Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable*.
+- [ITU-T G.650.3] Recommendation ITU-T G.650.3 (2017), *Test methods for installed single-mode optical fibre cable links*.
+- [ITU-T G.652] Recommendation ITU-T G.652 (2016), *Characteristics of a single-mode optical fibre cable*.
+- [ITU-T G.657] Recommendation ITU-T G.657 (2016), *Characteristics of a bending loss insensitive single-mode optical fibre and cable*.
+- [ITU-T L.100] Recommendation ITU-T L.100/L.10 (2021), *Optical fibre cables for duct and tunnel application*.
+- [ITU-T L.102] Recommendation ITU-T L.102/L.26 (2015), *Optical fibre cables for aerial application*.
+- [ITU-T L.103] Recommendation ITU-T L.103 (2016), *Optical fibre cables for indoor applications*.
+- [ITU-T L.109] Recommendation ITU-T L.109 (2018), *Construction of optical/metallic hybrid cables*.
+
+- [IEC 60227-1] IEC 60227-1:2007, *Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V – Part 1: General requirements.*
+- [IEC 60228] IEC 60228:2004, *Conductors of insulated cables.*
+- [IEC 60502-1] IEC 60502-1:2021, *Power cables with extruded insulation and their accessories for rated voltages from 1 kV ( $U_m = 1,2$  kV) up to 30 kV ( $U_m = 36$  kV) – Part 1: Cables for rated voltages of 1 kV ( $U_m = 1,2$  kV) and 3 kV ( $U_m = 3,6$  kV).*
+- [IEC 60793-2-10] IEC 60793-2-10:2019, *Optical fibres – Part 2-10: Product specifications – Sectional specification for category A1 multimode fibres.*
+- [IEC 60794-1-1] IEC 60794-1-1 (2015), *Optical fibre cables – Part 1-1: Generic specification – General.*
+- [IEC 60794-1-21] IEC 60794-1-21:2015, *Optical fibre cables – Part 1-21: Generic specification – Basic optical cable test procedures – Mechanical tests methods.*
+- [IEC 60794-2] IEC 60794-2:2017, *Optical fibre cables – Part 2: Indoor cables – Sectional specification.*
+- [IEC 60794-2-20] IEC 60794-2-20:2013, *Optical fibre cables – Part 2-20: Indoor cables – Family specification for multi-fibre optical cables.*
+- [IEC 60794-3] IEC 60794-3:2022, *Optical fibre cables – Part 3: Outdoor cables – Sectional specification.*
+- [IEC 60794-3-11] IEC 60794-3-11:2010, *Optical fibre cables – Part 3-11: Outdoor cables – Product specification for duct, directly buried, and lashed aerial single-mode optical fibre telecommunication cables.*
+- [IEC 60794-6] IEC 60794-6:2020, *Optical fibre cables – Part 6: Indoor-outdoor cables – Sectional specification for indoor-outdoor cables.*
+- [IEC 60794-6-10] IEC 60794-6-10:2020, *Optical fibre cables – Part 6-10: Indoor-outdoor cables – Family specification for universal indoor-outdoor cables.*
+- [IEC 60811-202] IEC 60811-202:2012/AMD1:2017, *Amendment 1 – Electric and optical fibre cables – Test methods for non-metallic materials – Part 202: General tests – Measurement of thickness of non-metallic sheath.*
+- [IEC 60811-203] IEC 60811-203:2012, *Electric and optical fibre cables – Test methods for non-metallic materials – Part 203: General tests – Measurement of overall dimensions.*
+- [IEC 60811-607] IEC 60811-607:2012, *Electric and optical fibre cables – Test methods for non-metallic materials – Part 607: Physical tests – Test for the assessment of carbon black dispersion in polyethylene and polypropylene.*
+- [IEC 61156-1] IEC 61156-1:2007, *Multicore and symmetrical pair/quad cables for digital communications – Part 1: Generic specification.*
+- [IEC 61156-1-4] IEC 61156-1-4:2018, *Multicore and symmetrical pair/quad cables for digital communications – Part 1-4: Assessment of conductor heating in bundled cables due to the deployment of remote powering.*
+- [IEC 61196-1-10x] IEC 61196-1-10x-series, *Coaxial communication cables – Parts 1-100 to 1-109: Electrical test methods series.*
+- [IEC 62807-1] IEC 62807-1:2017, *Hybrid telecommunication cables – Part 1: Generic specification.*
+
+# 3 Definitions
+
+For the purposes of this Recommendation, the definitions given in [ITU-T G.650.1], [ITU-T G.650.2], [ITU-T G.650.3], [ITU-T L.102], [ITU-T L.100], and [IEC 60794-1-1] apply.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|        |                                 |
+|--------|---------------------------------|
+| AP     | Access Point                    |
+| DAS    | Distributed Antenna Systems     |
+| DC     | Direct Current                  |
+| GFRP   | Glass Fibre Reinforced Polymer  |
+| IDF    | Intermediate Distribution Frame |
+| LAN    | Local Area Network              |
+| LSZH   | Low-smoke zero-halogen          |
+| MDF    | Main Distribution Frame         |
+| OD     | Outer Diameter                  |
+| OEHC   | Optical/Electrical Hybrid Cable |
+| OLT    | Optical Line Terminal           |
+| ONT    | Optical Network Terminal        |
+| ONU    | Optical Network Unit            |
+| PE     | Polyethylene                    |
+| PO-LAN | Passive Optical LAN             |
+| PVC    | Polyvinyl Chloride              |
+| RU     | Radio Unit                      |
+| SFP    | Small Form-factor Pluggable     |
+| UV     | Ultraviolet                     |
+| WAP    | Wireless Access Points          |
+
+# 5 Conventions
+
+None.
+
+# 6 Type II optical/electrical hybrid cable application scenario
+
+Deployment of OEHC can maximize the utilization of existing infrastructure to optimize the cost of deployment and maintenance. OEHC is classified into one of three types depending on the purpose of the optical and copper pair [ITU-T L.109]. It is mainly used in the drop-and-access section of the network, from the optical electrical hybrid power supply unit to various optical network terminals (ONTs), edge switches, and other application terminals, including wireless access points (WAPs), 5G small cells, digital billboards, public address systems, cameras, monitors, antennas, and smart manufacturing instruments. Figure 6-1 shows one typical application scenario for an OEHC.
+
+![Figure 6-1: Power and data delivery networking based on OEHC. The diagram shows three vertical zones: MDF, IDF, and Ceiling/desk. In the MDF, a Switch/OLT and RF headend are connected to the IDF via yellow fibre cables. In the IDF, a Power source and a Fibre/power distribution frame are present. The Fibre/power distribution frame is connected to the Ceiling/desk via four yellow hybrid cables. These cables connect to an ONU, Wi-Fi AP, Camera, and Small Cell. The ONU is connected to a PC and an IP phone via blue CATx cables. A note indicates that the ONU SFP is pluggable in the device. A legend at the bottom shows: CATx (blue), Copper (red), Fibre (yellow), and Hybrid (red/yellow). The reference L.109.1(22) is shown in the bottom right.](a5ee5c23b6dc52ec1d724b76d5a5f58f_img.jpg)
+
+Figure 6-1: Power and data delivery networking based on OEHC. The diagram shows three vertical zones: MDF, IDF, and Ceiling/desk. In the MDF, a Switch/OLT and RF headend are connected to the IDF via yellow fibre cables. In the IDF, a Power source and a Fibre/power distribution frame are present. The Fibre/power distribution frame is connected to the Ceiling/desk via four yellow hybrid cables. These cables connect to an ONU, Wi-Fi AP, Camera, and Small Cell. The ONU is connected to a PC and an IP phone via blue CATx cables. A note indicates that the ONU SFP is pluggable in the device. A legend at the bottom shows: CATx (blue), Copper (red), Fibre (yellow), and Hybrid (red/yellow). The reference L.109.1(22) is shown in the bottom right.
+
+**Figure 6-1 – Power and data delivery networking based on OEHC**
+
+In large venues, arenas, and/or stadiums, optical/electrical hybrid cables for access points and other terminal equipment are often used to supply power and data to multiple ONTs or edge switches in passive optical local area network (LAN), indoor distributed antenna systems (DAS) terminals, or outdoor small cells. In these use cases, several of these devices may be housed in an aggregation box which can effectively be served with a multi-fibre, multipair cable. Figure 6-2 shows another application scenario for OEHC on the fibre and power to the antenna.
+
+![Figure 6-2: OEHC application on the fibre and power to the zone and the small cell scenario. The diagram shows three vertical zones: MDF, IDF, and Ceiling/desk. In the MDF, a Switch/OLT and RF headend are connected to the IDF via yellow fibre cables. In the IDF, a Power source and a Fibre/power distribution frame are present. The Fibre/power distribution frame is connected to a Zone box in the Ceiling/desk via a red/yellow hybrid cable. The Zone box is connected to a Wi-Fi AP, PC, IP phone, Camera, and Small Cell via blue CATx cables. A legend at the bottom shows: CATx (blue), Copper (red), Fibre (yellow), and Hybrid (red/yellow). The reference L.109.1(22) is shown in the bottom right.](e6df2733626a85205c1db682e6259c46_img.jpg)
+
+Figure 6-2: OEHC application on the fibre and power to the zone and the small cell scenario. The diagram shows three vertical zones: MDF, IDF, and Ceiling/desk. In the MDF, a Switch/OLT and RF headend are connected to the IDF via yellow fibre cables. In the IDF, a Power source and a Fibre/power distribution frame are present. The Fibre/power distribution frame is connected to a Zone box in the Ceiling/desk via a red/yellow hybrid cable. The Zone box is connected to a Wi-Fi AP, PC, IP phone, Camera, and Small Cell via blue CATx cables. A legend at the bottom shows: CATx (blue), Copper (red), Fibre (yellow), and Hybrid (red/yellow). The reference L.109.1(22) is shown in the bottom right.
+
+**Figure 6-2 – OEHC application on the fibre and power to the zone and the small cell scenario**
+
+The OEHC containing the optical fibre for data transmission and copper wire for electrical power delivery to the multiple radio units (RU) distributed within a typical distance of less than 2000 m from the centralised power delivery station is shown in the Figure 6-3. The cable can be designed for multiple deployment scenarios to connect multiple termination points in series by containing multiple fibres and copper pairs in one cable. Centralised power delivery and power backup system are used to eliminate the power outage of active terminal devices (such as 5G RU).
+
+![Diagram of a centralised fibre connectivity and power delivery network based on multi fibre OEHC. The diagram is divided into two sections: 'Central location' and 'Street furniture'. In the 'Central location', a 'Centralized power/UPS' is connected to a 'Fibre/power distribution frame' by a red line (Copper). The 'Fibre/power distribution frame' is connected to a 'Transport hub' by a yellow line (Fibre). A dashed vertical line separates the 'Central location' from the 'Street furniture'. In the 'Street furniture', three 'Radio unit' blocks are shown. Each 'Radio unit' is connected to the 'Fibre/power distribution frame' by a red line (Copper). A yellow line (Fibre) runs from the 'Fibre/power distribution frame' to each 'Radio unit'. A legend at the bottom indicates: Red line = Copper, Yellow line = Fibre, Red dashed line = Hybrid. The reference 'L.109.1(22)' is shown in the bottom right corner.](cfef993dcc8fb513de79eb1f93cf26ae_img.jpg)
+
+Diagram of a centralised fibre connectivity and power delivery network based on multi fibre OEHC. The diagram is divided into two sections: 'Central location' and 'Street furniture'. In the 'Central location', a 'Centralized power/UPS' is connected to a 'Fibre/power distribution frame' by a red line (Copper). The 'Fibre/power distribution frame' is connected to a 'Transport hub' by a yellow line (Fibre). A dashed vertical line separates the 'Central location' from the 'Street furniture'. In the 'Street furniture', three 'Radio unit' blocks are shown. Each 'Radio unit' is connected to the 'Fibre/power distribution frame' by a red line (Copper). A yellow line (Fibre) runs from the 'Fibre/power distribution frame' to each 'Radio unit'. A legend at the bottom indicates: Red line = Copper, Yellow line = Fibre, Red dashed line = Hybrid. The reference 'L.109.1(22)' is shown in the bottom right corner.
+
+**Figure 6-3 – Centralised fibre connectivity and power delivery network based on multi fibre OEHC**
+
+The typical distance of these cabled links varies in accordance with the application requirements and can be as long as several hundred metres. This Recommendation considers an optical fibre that supports a bit rate of up to 1 Gbit/s and beyond.
+
+# 7 OEHC construction
+
+## 7.1 General
+
+The cable may be composed of one or more optical fibre cores and two or more current carrying electrical conductors under a common outer sheath. The conductor part is used as a remote power supply, with the power supply generally being  $\leq 100$  W, but higher electrical power can also be considered depending on the application scenarios.
+
+The design of the cable is related to the application area, so the construction type can be divided into outdoor, indoor and indoor/outdoor types. The technical specifications of the optical cables described in [IEC 60794-2], [IEC 60794-3] and [IEC 60794-6] should be used, depending on the circumstances and technical requirements.
+
+The make-up of the cable, particularly the number of fibres, the method of protecting the fibre, and the location of the strength members and metallic wires, should be clearly specified. Designs other than those described in clauses 7.4 to 7.15 may be used, provided that they comply with the aims of this Recommendation.
+
+In this Recommendation, the copper component of the cable is used exclusively for remote power delivery and not for data signal transmission.
+
+### 7.1.1 Fire safety
+
+Requirements for fire safety in different applications may differ depending on the country. Optical/metallic hybrid cables should meet the fire safety regulations in each country or be in accordance with each telecommunication carrier's requirements. [b-IEC TR 62222] should be considered if there are no fire safety specifications provided.
+
+### 7.1.2 Electrical power feeding wires
+
+Requirements for electrical performance in different applications may differ by country. Cable type designations and performance requirements should meet the electrical regulations in each country or be in accordance with the requirements of each telecommunication carrier.
+
+The conductor characteristics of the copper wire should comply with [IEC 60228], unless there is a different agreement between a manufacturer and a user. The insulation characteristics of the copper wire should be in accordance with the [IEC 60502-1] or [IEC 60227-1] standard requirements, unless there is a different agreement between a manufacturer and a user.
+
+## 7.2 Optical fibre element
+
+The following optical fibres or optical fibre elements can be used:
+
+- Single-mode optical fibres described in [ITU-T G.652], [ITU-T G.657], or multimode optical fibres described in [IEC 60793-2-10], should be used, depending on the circumstances and technical requirements.
+
+## 7.3 Optical fibre coating and requirements
+
+If a secondary coating or buffer is required, it should consist of one or more layers of polymeric material. The coating should be easily removable for fibre splicing. For tight/semi-tight buffers, the buffer and the fibre primary coating should be removable in one operation over a length depending on the customer's requirements. The nominal overall diameter of the tight/semi-tight secondary coating is typically 800/900 µm.
+
+## 7.4 Conductor requirements
+
+The conductor characteristics of the copper wire and conductors should comply with [IEC 60228], unless there is a different agreement between the manufacturer and user. The insulation characteristic of the copper wire should comply with the [IEC 60502-1] or [IEC 60227-1] standard requirements, unless there is a different agreement between the manufacturer and the user.
+
+The cross-section of the metallic wire should be chosen by taking into account transmission voltage, transmission distance and power consumption. Under extreme operating conditions, for example, when many cables are installed together in the same duct, the heat generated by the electrical conductors should not exceed the maximum allowed temperature specified for the cable element materials. The test recommendations for the temperature rise test of the cable should refer to [IEC 61156-1-4].
+
+The size of the conductor may refer to some commercial products. For example, conductor sizes between 0.404 mm and 1.290 mm can be found in [b-AWG].
+
+Conductors and insulation materials for power-feeding wires should be specified in detail.
+
+A power-feeding wire unit contains power-feeding wire(s) and is fabricated cylindrically with or without suitable material.
+
+The positive and negative poles of the conductor should be distinguished by the colour of the sheath or the colour bar.
+
+## 7.5 Strength member
+
+The cable should be designed with strength member(s) suitable to meet the installation and service conditions such that the fibre is not subjected to strain levels in excess of those agreed upon between the manufacturer and the user. The strength member(s) may be either metallic or non-metallic. When the metallic strength members are used, care should be taken to avoid hydrogen generation effects and lightning hazards.
+
+For indoor cables, it is recommended to use the conductor itself as the strength member. Non-metallic strength members can be added for particular installation environments.
+
+For an indoor-outdoor duct cable, it is recommended that non-metal strength members be used as the stronger part of cables, such as aramid yarns, fibreglass yarns, or glass fibre reinforced polymer (GFRP).
+
+For an outdoor duct cable, strength members mainly serve to limit tensile strain, but may also serve to limit compressive strain as in temperature changes. The strength members may be located within the core or in the sheath layers, or both.
+
+For outdoor aerial applications, it is recommended that the overhead suspension steel wires be used as an additional component for the 'figure-of-eight' cable type. Alternatively, the cable may be supported by attaching it to a supporting strand. Knowledge of the span, sag, wind and ice loads, as well as the permitted ground clearances is necessary when designing cables for use in aerial applications.
+
+Depending on particular conditions such as short distances or very light cables, the copper pair(s) present in the cable can be used as a reinforcement and/or pulling element.
+
+## **7.6 Yarn (optional)**
+
+Yarns may be used to provide enough tensile strength to meet the cable tensile requirements. Water blocking yarn may also be used. Yarns should be water-resistant and non-oil absorbing.
+
+## **7.7 Tape (optional)**
+
+The cable core may be protected by a tape or tapes, applied longitudinally or helically. The tape may provide thermal insulation, binding and/or provide dielectric properties. The material may be polyester, polyester non-woven tape, water-blocking tape or other suitable materials.
+
+## **7.8 Ripcord (optional)**
+
+A ripcord can be used. It should be non-hygroscopic, non-oil absorbing, and have enough strength to strip the cable sheath
+
+## **7.9 Inner sheath**
+
+If required, an inner sheath over the cable core and beneath the outer sheath with an optional armouring layer and shielding layer can be used. In indoor and indoor-outdoor applications, the material of the inner sheath can be fire retardant in order to meet local regulation requirements. It can be made of polyvinyl chloride (PVC), low-smoke zero-halogen (LSZH) flame-retardant polyolefin, or other materials. The minimum thickness of the conductor sheath must meet the requirements for insulation and the wall thickness of the optical fibre.
+
+The conductor jacket should have markings that identify the positive and negative poles, such as the colour, colour bar, and the corrugated cable.
+
+## **7.10 Screen or shield (optional)**
+
+When electromagnetic compatibility or lightning proofing is required, a screen can be added over the cable core. In passive optical local area network (PO-LAN) applications, the screen is able to reduce the current level induced by lightning, and minimize the electromagnetic noise induced by the current. The screen may consist of a single or double metal tape layers (or foil), single or double metal braid layers or a combined structure of metal braid and metal tape (or foil). A drain wire in contact with the metal shield layers can be used. A metallic sheath or continuous metal armouring layer can also act as the screen of the cable core.
+
+## **7.11 Moisture barrier (optional)**
+
+Filling a cable with water-blocking material or wrapping the cable core with layers of water-swellable material are two means of protecting fibres from water ingress. A water-blocking element (tapes or yarns, water swelling powder or a combination of materials) may be used. Any materials used should not be harmful to personnel. The materials in the cable should be compatible with each other and, in particular, should not adversely affect the fibre characteristics. These materials should not hinder
+
+splicing or connection operations. It is recommended to use a moisture barrier for outdoor and indoor-outdoor applications.
+
+## **7.12 Armouring (optional)**
+
+In applications where better mechanical performance is required for hybrid cable; an armouring layer can be added over the cable core. Armouring material can be either metallic or non-metallic.
+
+## **7.13 Outer sheath**
+
+The cable core should be covered with a sheath or sheaths suitable for the environmental and mechanical conditions associated with the storage, installation and operation. The sheath may be of a composite construction and may include strength members.
+
+Sheath considerations for optical fibre cables are generally the same as for metallic conductor cables. Consideration should also be given to the amount of hydrogen generated from a metallic moisture barrier. The minimum acceptable thickness of the sheath should be stated, together with any maximum and minimum allowable overall cable diameter.
+
+The selection of the sheath material is one of the important issues to be considered in order, for example, to ensure stability under the environmental conditions of installation, such as resistant to degradation due to ultraviolet (UV) radiation and biotic hazards, and to satisfy fire safety requirements. The outer sheath material of duct cables should optimize the friction forces between the cable sheath and the duct. Polyethylene (PE), polyvinyl chloride (PVC), outdoor low-smoke zero-halogen (LSZH) and thermoplastic polyurethane are typically used as cable sheath materials for outdoor cables. Fire-retardant sheath materials may vary for indoor or indoor-outdoor cables for fire safety reasons depending on the local regulations.
+
+The electrical tracking resistance of sheath materials may be an issue for type II cables.
+
+For passive optical LAN (PO-LAN) and other outdoor applications, the outer sheath of the hybrid cable should be able to resist ultraviolet rays and heat shock. The cable should have a seamless sheath made of UV-stabilized weather-resistant polyethylene, containing 2.0 % minimum well dispersed carbon black in accordance with [IEC 60811-607], unless otherwise agreed between the customer and the supplier.
+
+The sheath thickness (tested in accordance with [IEC 60811-202]) and the overall cable diameter (tested in accordance with [IEC 60811-203]) and its variations should consider the installation conditions and it shall be determined by the relevant specification or by agreement between the customer and the supplier.
+
+## **7.14 Sheath marking**
+
+It is recommended to provide a visual identification of optical-electrical hybrid cables: this can be done by visibly marking the outer sheath. For identifying cables, embossing, sintering, imprinting, hot foil or ink-jet or laser printing can be used by agreement between the user and supplier. Hybrid cable and cable units containing optical fibres and power-feeding units should be clearly coded in order to indicate that dangerous current flows through them and distinguish one type of unit from another. Colour coding and marking identification may be considered, however guidance differs in each country / region. Additional guidance on cable sheath marking can be found in [b-IEC TR 63194] and [b-ITU-T L.1203].
+
+## **7.15 Cable structure**
+
+Several recommended cable structures are shown in Figures 7-1 and 7-2 as examples. Other cables can also be used as long as they meet the actual requirements in the access scenarios.
+
+![Figure 7-1 – Rectangular cable designs. A) Indoor hybrid cable (Single sheath) showing Conductor unit, Fibre unit, and Sheath (Insulation). B) Indoor/outdoor hybrid cable (Double sheath) showing Sub cable, Outer sheath, and Strength member. C) Indoor/outdoor hybrid cable (Self-supporting) showing Conductor unit, Fibre unit, Sheath (Insulation), and Suspension part. Reference L.109.1(22).](33ed1f9b27c7c21c797aa928b0f06851_img.jpg)
+
+Figure 7-1 – Rectangular cable designs. A) Indoor hybrid cable (Single sheath) showing Conductor unit, Fibre unit, and Sheath (Insulation). B) Indoor/outdoor hybrid cable (Double sheath) showing Sub cable, Outer sheath, and Strength member. C) Indoor/outdoor hybrid cable (Self-supporting) showing Conductor unit, Fibre unit, Sheath (Insulation), and Suspension part. Reference L.109.1(22).
+
+**Figure 7-1 – Rectangular cable designs**
+
+![Figure 7-2 – Round cable designs. A) Indoor/outdoor hybrid cable (Rectangular core) showing Outer sheath, Sub cable, and Strength members and filler. B) Indoor/outdoor hybrid cable (One pair fibre and copper unit core) showing Outer sheath, Fibre unit, Negative wire, Positive wire, and Strength member and filler. C) Indoor/outdoor hybrid cable (Multi pairs fibre and copper units core) showing Outer sheath, Conductor units, Central element, Strength elements, Fibres, and Fibre unit. Reference L.109.1(22).](724c7777b608e53be38b12b6fb3c43bc_img.jpg)
+
+Figure 7-2 – Round cable designs. A) Indoor/outdoor hybrid cable (Rectangular core) showing Outer sheath, Sub cable, and Strength members and filler. B) Indoor/outdoor hybrid cable (One pair fibre and copper unit core) showing Outer sheath, Fibre unit, Negative wire, Positive wire, and Strength member and filler. C) Indoor/outdoor hybrid cable (Multi pairs fibre and copper units core) showing Outer sheath, Conductor units, Central element, Strength elements, Fibres, and Fibre unit. Reference L.109.1(22).
+
+**Figure 7-2 – Round cable designs**
+
+# 8 Rated values and characteristics
+
+## 8.1 Minimum bending radius for installation
+
+The standard installation tensile rating for cables is specified in Table 8-1.
+
+**Table 8-1 – Minimum bend**
+
+|                                         |                                |
+|-----------------------------------------|--------------------------------|
+| Standard minimum bend diameter          |                                |
+| Unloaded condition (Installed):         | 20 × Cable outer diameter (OD) |
+| Loaded condition (During installation): | 40 × Cable OD                  |
+
+## 8.2 Temperature range
+
+The normal temperature ranges for cables covered by this Recommendation are listed in Table 8-2.
+
+**Table 8-2 – Operating temperature**
+
+|                                   | Vertical riser |  | Horizontal |  |
+|-----------------------------------|----------------|--|------------|--|
+|                                   | °C             |  | °C         |  |
+| <u>Indoor</u>                     |                |  |            |  |
+| Operation                         | –20 to +70     |  | 0 to +70   |  |
+| Storage and shipping              | –40 to +70     |  | –40 to +70 |  |
+| Installation                      | –10 to 60      |  | 0 to 60    |  |
+| <u>Outdoor and indoor/outdoor</u> |                |  |            |  |
+| Operation                         | –40 to +70     |  | –40 to +70 |  |
+| Storage and shipping              | –40 to +70     |  | –40 to +70 |  |
+| Installation                      | –10 to 60      |  | 0 to 60    |  |
+
+## **8.3 Rated voltages**
+
+OEHC should adequately provide voltage for remote powering of distributed antenna systems, optical networks, small cells and more.
+
+The cross-section of the metallic wire should be designed in accordance with the transmission voltage, transmission distance and the power consumption. Under extreme operating conditions, the heat generated by the conductors should not make the cable temperature exceed the maximum allowed temperature of the cable element materials as specified in the detailed specifications under References.
+
+Specifications of conductors and insulation materials of the power feeding wires should also be specified in detail.
+
+# **9 Performance requirements and test methods**
+
+## **9.1 Optical requirements**
+
+The cable element (optical fibre) performance requirements and supported applications for indoor, outdoor and indoor/outdoor are as specified in [IEC 60794-2], [IEC 60794-3], and [IEC 60794-6] respectively.
+
+## **9.2 Electrical requirements**
+
+Electrical characteristics of hybrid cable should include the voltage test, insulation resistance, conductor resistance of power-feeding wires and electrical characteristics of symmetrical metallic pairs listed in clause 7.1.2. Test methods of the voltage test, insulation resistance and conductor resistance of power-feeding wires should comply with [IEC 60502-1] or [IEC 60227-1]. Test methods for electrical characteristics of symmetrical pairs should comply with [IEC 61156-1]. Assessment of conductor heating in bundled cables due to the deployment of remote powering should comply with [IEC 61156-1-4]. Test methods for the electrical characteristics of coaxial units should comply with documents in the series [IEC 61196-1-10x].
+
+### **9.2.1 Resistance of conductors**
+
+Test method: [IEC 60227-1]
+
+Requirement: Direct current (DC) resistance at 20°C  $\leq 0.017241\Omega\cdot\text{m}^2/\text{m}$
+
+### **9.2.2 Voltage test on the completed cable**
+
+Test method: [IEC 60227-1]
+
+Voltage and duration: 2000V for 5 minutes
+
+Requirement: No breakdown
+
+### **9.2.3 Voltage test on cores**
+
+Test method: [IEC 60227-1]
+
+Voltage and duration: 2000V for 5 minutes
+
+Requirement: No breakdown
+
+### **9.2.4 Insulation resistance at 80°C**
+
+Test method: [IEC 60227-1]
+
+Requirement: Insulation resistance at 80°C  $\geq 0.0094\text{ M}\Omega\cdot\text{km}$
+
+### 9.2.5 Temperature rise test
+
+Test method:
+
+- 1) [IEC 61156-1-4] Multicore and symmetrical pair/quad cables for digital communications – Part 1-4: Assessment of conductor heating in bundled cables due to the deployment of remote powering.
+- 2) DC current 2 A, ambient 70°C, maximum, under sealed duct conditions.
+
+Requirement:
+
+1. Temperature rise cannot exceed 10°C.
+2. No visible damage is found on the sheath surface.
+
+## 9.3 Mechanical requirements
+
+Unless there is a different agreement between the manufacturer and the user, an OEHC should have the mechanical characteristics specified in [ITU-T L.103] and [IEC 62807-1], depending on the installation environment.
+
+### 9.3.1 Tensile performance
+
+Test method: Method E1, [IEC 60794-1-21]
+
+The allowable tensile force should meet the specific requirements of the application and the cable construction type.
+
+The recommended tensile force value should be based on the cable construction, however other force requirements can also be determined based on the application requirements.
+
+The tensile performance test methods and requirements are given in Table 9-1.
+
+**Table 9-1 – Tensile performance test methods and requirements**
+
+|             | Indoor                         | Outdoor                        | Indoor/outdoor                 |
+|-------------|--------------------------------|--------------------------------|--------------------------------|
+| Method      | [IEC 60794-1-21-E1A]           | [IEC 60794-1-21-E1A]           | [IEC 60794-1-21-E1A]           |
+| Requirement | [IEC 60794-2-20] Section 4.3.1 | [IEC 60794-3-11] Section 7.5.5 | [IEC 60794-6-10] Section 6.2.2 |
+
+### 9.3.2 Crush performance
+
+Test method: Method E3, [IEC 60794-1-21]
+
+The allowable crush force should meet the specific requirements of the application and the cable construction type.
+
+The crush performance test methods and requirements are given in Table 9-2.
+
+**Table 9-2 – Crush performance test methods and requirements**
+
+|             | Indoor                         | Outdoor                        | Indoor/outdoor                 |
+|-------------|--------------------------------|--------------------------------|--------------------------------|
+| Method      | [IEC 60794-1-21-E3]            | [IEC 60794-1-21-E3]            | [IEC 60794-1-21-E3]            |
+| Requirement | [IEC 60794-2-20] Section 4.3.2 | [IEC 60794-3-11] Section 7.5.4 | [IEC 60794-6-10] Section 6.2.4 |
+
+### 9.3.3 Bend
+
+Test method: Method E11A, [IEC 60794-1-21]
+
+The allowable bend should meet the specific requirements of the application and the cable construction type.
+
+The bend performance test methods and requirements are given in Table 9-3.
+
+**Table 9-3 – Bend performance test methods and requirements**
+
+|             | <b>Indoor</b>                  | <b>Outdoor</b>                 | <b>Indoor/outdoor</b>          |
+|-------------|--------------------------------|--------------------------------|--------------------------------|
+| Method      | [IEC 60794-1-21-E11A]          | [IEC 60794-1-21-E11A]          | [IEC 60794-1-21-E11A]          |
+| Requirement | [IEC 60794-2-20] Section 4.3.4 | [IEC 60794-3-11] Section 7.5.2 | [IEC 60794-6-10] Section 6.2.8 |
+
+### 9.3.4 Repeated bending
+
+Test method: Method E6, [IEC 60794-1-21]
+
+The allowable repeated bending should meet the specific requirements of the application and the cable construction type.
+
+The repeated bending performance test methods and requirements are given in Table 9-4.
+
+**Table 9-4 – Repeated bending performance test methods and requirements**
+
+|             | <b>Indoor</b>                  | <b>Outdoor</b>                 | <b>Indoor/outdoor</b>          |
+|-------------|--------------------------------|--------------------------------|--------------------------------|
+| Method      | [IEC 60794-1-21-E6]            | [IEC 60794-1-21-E6]            | [IEC 60794-1-21-E6]            |
+| Requirement | [IEC 60794-2-20] Section 4.3.5 | [IEC 60794-3-11] Section 7.5.7 | [IEC 60794-6-10] Section 6.2.6 |
+
+### 9.3.5 Bending at low temperature
+
+Test method: Method E11A, [IEC 60794-1-21]
+
+The allowable bending at low temperatures should meet the specific requirements of the application and the cable construction type.
+
+The bending performance at low temperature test methods requirements are given in Table 9-5.
+
+**Table 9-5 – Bending performance at low temperature test methods and requirements**
+
+|             | <b>Indoor</b>                  | <b>Outdoor</b>                 | <b>Indoor/outdoor</b>          |
+|-------------|--------------------------------|--------------------------------|--------------------------------|
+| Method      | [IEC 60794-1-21-E11A]          | [IEC 60794-1-21-E11A]          | [IEC 60794-1-21-E11A]          |
+| Requirement | [IEC 60794-2-20] Section 4.3.7 | [IEC 60794-3-11] Section 7.5.2 | [IEC 60794-6-10] Section 6.2.8 |
+
+# Appendix I
+
+## Chinese experience
+
+(This appendix does not form an integral part of this Recommendation.)
+
+## I.1 Introduction
+
+In the PO-LAN optical access network, hybrid cables containing both optical fibres and copper cables are developing rapidly. The hybrid cable is used to transmit optical data signals and power supply to active devices.
+
+Power over hybrid cable technology is fast becoming a vital component in campus optical systems. The system consists of the power supply unit, optical/electrical hybrid cable, optical/electrical hybrid adapter, and the optical/electrical hybrid connector. These can transmit optical signals and electrical power at the same time and are cost-effective and easy to install.
+
+## I.2 Cable structure
+
+The optical/electrical hybrid cable has been successfully installed and operated in a campus optical access network in the People's Republic of China (PRC).
+
+Figures I.1 and I.2 show the structure of an optical/electrical hybrid cable.
+
+![Cross-section diagram of an indoor optical/electrical hybrid cable.](07f72fad02dad5056cf76b429709a802_img.jpg)
+
+This diagram shows a cross-section of an indoor optical/electrical hybrid cable. The cable has a grey, pill-shaped insulation sheath. Inside, there are two groups of brown circular conductors, one at the top and one at the bottom. In the center, there is a white circular tight buffer optical fibre. An 'Open notch' is indicated by an arrow pointing to the left side of the cable. A 'Positive color strip' is shown as a red oval at the bottom right. The label 'L.109.1(22)' is at the bottom right.
+
+Cross-section diagram of an indoor optical/electrical hybrid cable.
+
+Figure I.1 – Indoor optical/electrical hybrid cable
+
+![Cross-section diagram of an indoor/outdoor optical/electrical hybrid cable.](86b435d3ff1e3454a85a4c9e3e5e4ff4_img.jpg)
+
+This diagram shows a cross-section of an indoor/outdoor optical/electrical hybrid cable. It features a central grey indoor sub-cable (identical to Figure I.1) surrounded by a yellow layer of aramid/glass/WB yarns, which is further enclosed by a thick black outdoor LSZH (Low Smoke Zero Halogen) jacket. Red arrows point from the labels on the right to each of these three concentric layers. The label 'L.109.1(22)' is at the bottom right.
+
+Cross-section diagram of an indoor/outdoor optical/electrical hybrid cable.
+
+Figure I.2 – Indoor/outdoor optical/electrical hybrid cable
+
+This type of hybrid cable is used for single-fibre bidirectional data signal transmission. The conductors of the copper cable are two flexible wires without the jacket and are used to supply the electrical power.
+
+The cable can be terminated with an optical/electrical hybrid connector that carries optical signals and electrical power alongside each other. This solution improves the operational simplicity because the optical and electrical connections can be made and unmade in a single action.
+
+The transmission distance of this kind of optical/electrical hybrid cable assembly ranges from 100 m (71.3 W) to 800 m (15 W).
+
+Table I.1 gives the recommended sizes of an optical/electrical hybrid cable (OEHC) construction.
+
+**Table I.1 – Recommended sizes of an OEHC construction**
+
+| Type of cable           | Dimensions (mm)    | Shape                                                  |
+|-------------------------|--------------------|--------------------------------------------------------|
+| Indoor drop             | $\leq 3 \times 6$  | rectangular                                            |
+| Indoor/outdoor duct     | $\leq 5 \times 8$  | rectangular                                            |
+| Indoor/outdoor duct     | $\leq 8$           | round                                                  |
+| Indoor/outdoor overhead | $\leq 3 \times 10$ | Shape examples are shown in Figure 7-1 and Figure 7-2. |
+
+## I.3 Application network
+
+One end of an optical/electrical hybrid cable assembly is connected to the power supply unit through the hybrid connector, and the other end is connected to an optical port that supports the hybrid connector to transmit and supply optical data to the optical network unit (ONU). Figure I.3 shows the power supply networking for the hybrid cable ONU.
+
+![Diagram of power supply networking for the hybrid cable ONU. An OEHC cable power box is connected via an optical/electrical hybrid adapter to one end of an OEHC cable. The other end of the OEHC cable is connected via another optical/electrical hybrid connector to an ONU. The ONU is also connected to an optical/electrical hybrid adapter. The diagram includes labels for the OEHC cable power box, optical/electrical hybrid adapter, OEHC cable, and ONU. A reference code L.109.1(22) is present in the bottom right corner of the diagram area.](1a85642ed2356d183ce598f2c8b3ee8b_img.jpg)
+
+Diagram of power supply networking for the hybrid cable ONU. An OEHC cable power box is connected via an optical/electrical hybrid adapter to one end of an OEHC cable. The other end of the OEHC cable is connected via another optical/electrical hybrid connector to an ONU. The ONU is also connected to an optical/electrical hybrid adapter. The diagram includes labels for the OEHC cable power box, optical/electrical hybrid adapter, OEHC cable, and ONU. A reference code L.109.1(22) is present in the bottom right corner of the diagram area.
+
+**Figure I.3 – Power supply networking for the hybrid cable ONU**
+
+The optical/electrical hybrid cable assembly can also connect the optical port of the hybrid connector to the hybrid small form-factor pluggable (SFP) ONU to carry the access point (AP) and the camera. If the AP and the camera do not have optical ports, they can be connected using separate optical and electrical connectors.
+
+## Bibliography
+
+- [b-ITU-T L.1203] Recommendation ITU-T L.1203 (2016), *Colour and marking identification of up to 400 VDC power distribution for information and communication technology systems.*
+- [b-AWG] ASTM B258-18 (2018), *Standard Specification for Standard Nominal Diameters and Cross-Sectional Areas of AWG Sizes of Solid Round Wires Used as Electrical Conductors*, ASTM international.  
+<https://www.astm.org/b0258-18.html>
+- [b-IEC TR 62222] IEC TR 62222:2021, *Fire performance of communication cables installed in buildings.*  
+<https://standards.iteh.ai/catalog/standards/iec/ebf8353d-6275-4aa8-9c83-7d053acf65b5/iec-tr-62222-2021>
+- [b-IEC TR 63194] IEC TR 63194:2019, *Guidance on colour coding of optical fibre cables.*  
+<https://standards.iteh.ai/catalog/standards/iec/604faf3f-23a5-44ab-a4d7-f38d073ac438/iec-tr-63194-2019>
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

marked/L/T-REC-L.1200-201205-I_PDF-E/raw.md

@@ -0,0 +1,438 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**L.1200**
+
+(05/2012)
+
+SERIES L: CONSTRUCTION, INSTALLATION AND  
+PROTECTION OF CABLES AND OTHER ELEMENTS OF  
+OUTSIDE PLANT
+
+---
+
+**Direct current power feeding interface up to  
+400 V at the input to telecommunication and ICT  
+equipment**
+
+Recommendation ITU-T L.1200
+
+
+
+# Recommendation ITU-T L.1200
+
+# Direct current power feeding interface up to 400 V at the input to telecommunication and ICT equipment
+
+## Summary
+
+Recommendation ITU-T L.1200 specifies the direct current (DC) interface between the power feeding system and ICT equipment connected to it. It also describes normal and abnormal voltage ranges, and immunity test levels for ICT equipment to maintain the stability of telecommunication and data communication services. The specified interface is operated from a DC power source of up to 400 V to allow increased power consumption and equipment power density, in order to obtain higher energy efficiency and reliability with less material usage than using a lower voltage such as –48 VDC or AC UPS power feeding solutions.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group |
+|---------|----------------|------------|-------------|
+| 1.0     | ITU-T L.1200   | 2012-05-29 | 5           |
+
+## Keywords
+
+Data centre, direct current, energy efficiency, ICT equipment, power feeding system, reliability, telecommunication centre.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2012
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                           | Page |
+|-----------------------------------------------------------|------|
+| 1 Scope .....                                             | 1    |
+| 2 References.....                                         | 1    |
+| 3 Definitions .....                                       | 2    |
+| 3.1 Terms defined elsewhere .....                         | 2    |
+| 3.2 Terms defined in this Recommendation.....             | 2    |
+| 4 Abbreviations and acronyms .....                        | 2    |
+| 5 Conventions .....                                       | 2    |
+| 6 DC power feeding interface specification .....          | 2    |
+| 6.1 Definition of DC power feeding interface.....         | 3    |
+| 6.2 Voltage range at interface P .....                    | 3    |
+| 6.3 Reference test voltage ( $U_T$ ) at interface P ..... | 4    |
+| 6.4 Abnormal conditions .....                             | 4    |
+| 6.5 Inrush current.....                                   | 7    |
+| Appendix I – Information on grounding method .....        | 8    |
+| I.1 Basic configuration.....                              | 8    |
+| I.2 Specification for PE at interface P.....              | 8    |
+| Bibliography.....                                         | 10   |
+
+## Introduction
+
+This Recommendation specifies a power feeding system for ICT equipment with a DC voltage of up to 400 V.
+
+This Recommendation takes into consideration the improvements in energy efficiency as well as the reduction in greenhouse gas (GHG) emissions and raw materials that are enabled by using the 'up to 400 VDC' power feeding system. The 'up to 400 VDC' power feeding system was developed, due to increased power consumption and equipment power density, in order to obtain a higher energy efficiency with less material consumption than using a lower voltage such as –48 VDC or AC UPS power feeding solutions. One of the advantages of 'up to 400 VDC' power feeding is that it reduces intermediate power conversion stages (e.g., the inverter and power factor compensator can be eliminated) and it is lower current usage than –48 V feeding for the same power requirement, thereby improving the efficiency and reliability of the entire power feeding system.
+
+This Recommendation is concerned with the requirements for the interface between the power feeding system and telecommunication and ICT equipment. It also includes requirements relating to its stability, safety and measurement. Reliability and scalability are easier to improve in DC compared to AC because phase synchronization and inverters are not required. The system architecture is also simpler.
+
+The purpose of the 'up to 400 VDC' interface is to facilitate interworking of different loads, standardization of power feeding systems for ICT equipment, and installation, operation and maintenance of ICT equipment and systems with different origins.
+
+In addition, the DC interface can also simplify the use of renewable energy power sources with DC output such as photovoltaic generators and fuel cell systems.
+
+## Recommendation ITU-T L.1200
+
+## Direct current power feeding interface up to 400 V at the input to telecommunication and ICT equipment
+
+# 1 Scope
+
+This Recommendation is aimed at providing compatibility between the power feeding system and ICT equipment installed at telecommunication centres, data centres and customer premises. This Recommendation deals with the requirements for an up to 400 VDC interface between power feeding system and ICT equipment.
+
+This Recommendation covers the following main items:
+
+- The identification of a power feeding system with the same characteristics for all ICT equipment defined in any location where an up to 400 VDC interface is used, e.g., telecommunication centres, radio base stations, data centres and customer premises.
+- The 'up to 400 VDC' voltage range in normal and abnormal service conditions at the interface defined in this Recommendation.
+- Behaviour during voltage variation, dips, short interruptions, transients, inrush current, grounding, etc.
+
+The general requirements for safety and earthing and bonding are out of the scope of this Recommendation unless specific requirements are not defined in current standards.
+
+# 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+- [IEC 60445] IEC 60445 (2010), *Basic and safety principles for man-machine interface, marking, and identification – Identification of equipment terminals, conductor terminations, and conductors.*
+- [IEC 61000-4-5] IEC 61000-4-5 (2005), *Electromagnetic compatibility (EMC) – Part 4-5: Testing and measurement techniques – Surge immunity test.*
+- [IEC 61000-4-29] IEC 61000-4-29 (2000), *Electromagnetic compatibility (EMC) – Part 4-29: Testing and measurement techniques – Voltage dips, short interruptions and voltage variations on d.c. input power port immunity tests.*
+- [ETSI EN 300-132-3-1] ETSI EN 300-132-3-1 (2012), *Environmental Engineering (EE); Power supply interface at the input to telecommunications and datacom (ICT) equipment; Part 3: Operated by rectified current source, alternating current source, or direct current source up to 400 V subpart 1: direct current (DC) up to 400 V solution.*
+
+# 3 Definitions
+
+## 3.1 Terms defined elsewhere
+
+None.
+
+## 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 abnormal DC voltage range:** DC voltage range at interface P where ICT equipment may not operate within its specification, but is not damaged.
+
+**3.2.2 DC voltage range:** DC voltage range at interface P.
+
+**3.2.3 ICT equipment:** Information and communication equipment (e.g., switch, transmitter, router, server, and peripheral devices) used in telecommunication centres, data centres and customer premises.
+
+**3.2.4 interface P:** Interface, physical point, at which power feeding system is connected to operate ICT equipment. Refer to Figure 1.
+
+**3.2.5 normal DC voltage range:** DC voltage range at interface P where ICT equipment operates within its specification.
+
+**3.2.6 power feeding system:** Power source to which ICT equipment is intended to be connected.
+
+# 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+AC Alternating Current (also when used as a suffix to units of measurement)
+
+DC Direct Current (also when used as a suffix to units of measurement)
+
+EMC Electromagnetic Compatibility
+
+GHG Green House Gas
+
+ICT Information and Communication Technology
+
+PE Protective Earth
+
+Rg Resistance for the grounding system
+
+UPS Uninterruptible Power Supply
+
+$U_T$  Reference test voltage
+
+$V_o$  output Voltage of power feeding system
+
+VDC Volts DC
+
+# 5 Conventions
+
+None.
+
+# 6 DC power feeding interface specification
+
+This clause describes the DC power feeding interface to ICT equipment in data centres, telecommunication centres and customer premises.
+
+## 6.1 Definition of DC power feeding interface
+
+![Figure 1: Definition of interface P. A diagram showing a 'Power feeding system' on the left connected to 'ICT equipment' on the right at 'Interface P'. The power feeding system has three terminals: (+), (-), and PE. The ICT equipment is represented by a rectangle. The diagram is labeled L.1200(12)_F01.](acfc53eca625d62b38aa2563efa95c3e_img.jpg)
+
+The diagram shows a 'Power feeding system' on the left connected to 'ICT equipment' on the right at 'Interface P'. The power feeding system has three terminals: (+), (-), and PE. The ICT equipment is represented by a rectangle. The diagram is labeled L.1200(12)\_F01.
+
+Figure 1: Definition of interface P. A diagram showing a 'Power feeding system' on the left connected to 'ICT equipment' on the right at 'Interface P'. The power feeding system has three terminals: (+), (-), and PE. The ICT equipment is represented by a rectangle. The diagram is labeled L.1200(12)\_F01.
+
+**Figure 1 – Definition of interface P**
+
+The power feeding interface, shown as interface P in Figure 1, is a physical point at which all the requirements apply. This point is situated between the power feeding system and ICT equipment in accordance with [IEC 60445].
+
+In this clause, all specifications are defined at the input of ICT equipment.
+
+Figure 2 shows a typical use of interface P.
+
+![Figure 2: Illustration of power feeding system and ICT equipment. A block diagram showing 'AC mains' connected to a 'Rectifier' (containing an 'AC/DC converter'). The 'Rectifier' is part of the 'Power feeding system'. The 'Rectifier' outputs 'DC power' to 'ICT equipment' at 'Interface P'. A 'Battery system' is also connected to the 'Rectifier'. A note indicates that definitions such as DC voltage range are defined at this interface point. The diagram is labeled L.1200(12)_F02.](dbe553cf16dd14073b89a8263a428664_img.jpg)
+
+The diagram shows 'AC mains' connected to a 'Rectifier' (containing an 'AC/DC converter'). The 'Rectifier' is part of the 'Power feeding system'. The 'Rectifier' outputs 'DC power' to 'ICT equipment' at 'Interface P'. A 'Battery system' is also connected to the 'Rectifier'. A note indicates that definitions such as DC voltage range are defined at this interface point. The diagram is labeled L.1200(12)\_F02.
+
+Figure 2: Illustration of power feeding system and ICT equipment. A block diagram showing 'AC mains' connected to a 'Rectifier' (containing an 'AC/DC converter'). The 'Rectifier' is part of the 'Power feeding system'. The 'Rectifier' outputs 'DC power' to 'ICT equipment' at 'Interface P'. A 'Battery system' is also connected to the 'Rectifier'. A note indicates that definitions such as DC voltage range are defined at this interface point. The diagram is labeled L.1200(12)\_F02.
+
+**Figure 2 – Illustration of power feeding system and ICT equipment**
+
+## 6.2 Voltage range at interface P
+
+### 6.2.1 Normal DC voltage range
+
+The maximum environmental benefit will only be achieved by transitioning towards a single voltage interface: the target solution.
+
+However, it is also recognized that there have already been some regional developments in DC for powering ICT equipment. To take advantage of the benefits resulting from a single voltage range interface (the target solution), a transitional period will be specified during which a transitional solution is allowed towards the single DC voltage range at the input of the ICT equipment.
+
+The target delay for full implementation of the target solution shall be as short as possible from the date of publication of this Recommendation.
+
+##### Target solution
+
+This solution has the following characteristics:
+
+The normal voltage range is the range of steady-state voltage over which ICT equipment shall maintain a specified normal service.
+
+- The minimum voltage is 260 V.
+- The maximum voltage is 400 V.
+
+The voltage at the output of the power supply must take into account the voltage drop in the cable at a maximum steady current.
+
+Any new ICT equipment or electrical room installation compliant with this Recommendation shall use this target voltage range (260-400 V).
+
+##### **Transitional solution**
+
+The transitional voltage range over which ICT equipment shall maintain a specified normal service is 192 V-288 V.
+
+This can be used for the migration of DC systems towards the recommended target voltage range for a limited time in some regions.
+
+### **6.2.2 Abnormal DC voltage range**
+
+ICT equipment may be subjected to steady-state voltage out of the normal DC voltage range for the target solution. The limits of an abnormal DC voltage range for the target solution are defined as follows:
+
+- $0 \text{ V} < U < 260 \text{ V}$ .
+- $400 \text{ V} < U < 410 \text{ V}$ .
+
+After the restoration of the supply from the abnormal DC voltage range to the normal DC voltage range, the ICT equipment shall not incur any damage and will be able to automatically resume operation according to its specifications when the voltage comes back into the normal DC voltage range.
+
+## **6.3 Reference test voltage ( $U_T$ ) at interface P**
+
+Reference test voltages ( $U_T$ ) for the target solution at interface P for ICT equipment are defined as  $U_T = 380 \text{ V}$  or  $U_T = 300 \text{ V}$  depending on system requirements.
+
+NOTE – Different  $U_T$  can be defined because there can be different operating voltages inside the target voltage range.
+
+## **6.4 Abnormal conditions**
+
+Under abnormal conditions, voltage values outside the normal DC voltage range for the target solution may occur for a short time. The deviations from the steady-state voltage at interface P may be caused by:
+
+- voltage variations;
+- voltage dips;
+- voltage interruptions;
+- voltage surges/transients.
+
+The tests for voltage dips, short interruptions and voltage variations shall be conducted in accordance with [IEC 61000-4-29].
+
+The tests for voltage surges shall be conducted in accordance with [IEC 61000-4-5].
+
+Specific criteria for ICT equipment are defined in the tables below which display testing details. The detailed specifications of the generator are in Annex F of [ETSI EN 300-132-3-1]. The tests shall be performed on individual modules/subsystems.
+
+### **Compliance criteria are as follows:**
+
+Criteria a) ICT equipment shall continue to operate as intended during and after the test. No degradation of performance or loss of function is allowed below a performance level specified by the manufacturer for when the ICT equipment is used as intended.
+
+Criteria b) Temporary loss of function or degradation of performance should cease after the disturbance ceases and the equipment under test should return to its normal performance level, without operator intervention.
+
+### 6.4.1 Voltage variation
+
+The voltage variation at interface P shall be tested by referring to [ETSI EN 300-132-3-1]. The condition and compliance criteria for testing are in Table 1.
+
+**Table 1 – Test levels, duration and compliance criteria for voltage variation**
+
+| <b>Voltage</b>                     | <b>Duration</b> | <b>Compliance criteria on ICT equipment</b>                                                                                       | <b>Comments</b>                                                                      |
+|------------------------------------|-----------------|-----------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------------------------------|
+| From $U_T$ to 260 V, back to $U_T$ | 1 min           | Criteria a)<br>Normal performance                                                                                                 | Test of minimum operating voltage at interface P within the normal DC voltage range. |
+| From $U_T$ to 400 V, back to $U_T$ | 1 min           | Criteria a)<br>Normal performance                                                                                                 | Test of maximum operating voltage at interface P within the normal DC voltage range. |
+| From $U_T$ to 410 V, back to $U_T$ | 1 s             | Criteria b)<br>Temporary loss of function or degradation of performance; automatic recovery to normal performance after the test. | Test of voltage increase variation entering the abnormal DC voltage range.           |
+| From $U_T$ to 420 V, back to $U_T$ | 10 ms           | Criteria b)<br>Temporary loss of function or degradation of performance; automatic recovery to normal performance after the test. | Test of voltage increase variation outside the abnormal DC voltage range.            |
+
+### 6.4.2 Voltage dips
+
+The voltage interruption at interface P shall be tested by referring to [ETSI EN 300-132-3-1]. The condition and compliance criteria for testing are in Table 2.
+
+**Table 2 – Test levels, duration and compliance criteria for voltage dips**
+
+| <b>Voltage</b>                    | <b>Duration</b> | <b>Compliance criteria on ICT equipment</b> | <b>Comments</b>                                                                      |
+|-----------------------------------|-----------------|---------------------------------------------|--------------------------------------------------------------------------------------|
+| From $U_T$ to 260V, back to $U_T$ | 10 ms           | Criteria a)<br>Normal performance           | Test of minimum operating voltage at interface P within the normal DC voltage range. |
+
+### 6.4.3 Short interruptions
+
+The short interruption at interface P shall be tested by referring to [ETSI EN 300-132-3-1]. The condition and compliance criteria for testing are in Table 3.
+
+**Table 3 – Test levels, duration and compliance criteria for short interruptions**
+
+| Voltage                    | Supply network                | Duration | Compliance criteria on ICT equipment                                                                                              | Comments                                                                                                  |
+|----------------------------|-------------------------------|----------|-----------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------|
+| $U_T$ to 0 V back to $U_T$ | Low impedance (short circuit) | 10 ms    | Criteria a)<br>Normal performance                                                                                                 | Test of hold-up time during fault clearing due to a short-circuit in the system.                          |
+| $U_T$ to 0 V back to $U_T$ | High impedance (open circuit) | 1 s      | Criteria b)<br>Temporary loss of function or degradation of performance, automatic recovery to normal performance after the test. | Test of automatic recovery after an extended (>1 s) interruption of the operating voltage at interface P. |
+
+NOTE 1 – With reference to clauses 6.1.1 and 6.1.2 of [IEC 61000-4-29] the definition of low impedance is a generator output impedance  $< 0.5 \Omega$  and high impedance  $> 100 k \Omega$ .
+
+NOTE 2 – The purpose of the second test above ("High impedance") is to test the performance of the system during a power start-up of the system from 0 V (i.e., all system capacitors are fully discharged). This reflects the reset of a tripped circuit-breaker on interface P or DC interruptions in the network caused by transient voltage. This reset can also occur with the recovery of interface P voltage following the restoration of AC mains after an AC mains interruption longer than the battery backup time.
+
+### 6.4.4 Voltage surges/transients
+
+The voltage surges at interface P shall be tested by referring to [IEC 61000-4-5] and [ETSI EN 300-132-3-1]. The condition and compliance criteria for testing are in Table 4.
+
+Voltage surges may occur at interface P when faults (e.g., short circuits) occur in the power distribution system.
+
+The voltage surges due to short circuits and protective device clearance are characterized by a voltage drop in the abnormal voltage range, followed by an overvoltage often in excess of the maximum abnormal voltage range and dependent upon the power distribution up to interface P and the ICT equipment connected to interface P.
+
+The purpose of this clause is thus to address the energy and subsequent so-called "fuse blowing surge" associated with a short circuit.
+
+Other voltage surges induced from other external sources, e.g., faults on the AC mains or lightning, belong to EMC generic requirements and are outside the scope of this Recommendation.
+
+Due to the lack of commercial test generators for testing voltage surges, according to this clause, references are, however, given for the EMC standard to reuse the so-called combination generator specified in [IEC 61000-4-5].
+
+**Table 4 – Test levels, wave shape and compliance criteria for voltage surges/transients**
+
+| Test voltage | Supply network | Wave shape                                 | Compliance criteria on ICT equipment | Comments                                                                                                                                                                  |
+|--------------|----------------|--------------------------------------------|--------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 500 V        | Line to line   | 1.2/50 $\mu\text{s}$ (8/20 $\mu\text{s}$ ) | Criteria a)<br>Normal performance    | Test of voltage increase variation outside the abnormal voltage range (e.g., due to fuse blow, switching).<br>Test voltage polarity shall be the same as for interface P. |
+
+**Table 4 – Test levels, wave shape and compliance criteria for voltage surges/transients**
+
+| Test voltage | Supply network | Wave shape             | Compliance criteria on ICT equipment                                                                                           | Comments                                                                                                                                                                  |
+|--------------|----------------|------------------------|--------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| 500 V        | Line to ground | 1.2/50 µs<br>(8/20 µs) | Criteria a)<br>Normal performance                                                                                              | Test of voltage increase variation outside the abnormal voltage range (e.g., due to fuse blow, switching).<br>Test voltage polarity shall be the same as for interface P. |
+| 2 kV         | Line to line   | 1.2/50 µs<br>(8/20 µs) | Criteria b)<br>Temporary loss of function degradation of performance, automatic recovery to normal performance after the test. | Test of automatic system recovery after a line-to-line short-circuit condition.<br>Test voltage polarity shall be the same as for interface P.                            |
+| 2 kV         | Line to ground | 1.2/50 µs<br>(8/20 µs) | Criteria b)<br>Temporary loss of function degradation of performance, automatic recovery to normal performance after the test. | Test of automatic system recovery after a line-to-ground (line-to-PE) short-circuit condition.<br>Test voltage polarity shall be the same as for interface P.             |
+
+NOTE 1 – Lengthening of the interruption to service (equipment is not functioning as intended) due to the recovery of software should be declared in the test report (i.e., details about the service interruption).
+
+NOTE 2 – To prevent system malfunctioning, additional arrangements concerning the power supply system may be necessary.
+
+For example:
+
+- dual feeding system;
+- high ohmic distribution system;
+- independent power distribution.
+
+NOTE 3 – Special precautions are normally taken in power distribution networks to fulfil compliance criteria a) for mission critical ICT equipment, i.e., to prevent functional disturbances due to the voltage surges treated in this clause.
+
+## 6.5 Inrush current
+
+The inrush current pulse shall be limited in magnitude and in time duration to avoid protective devices clearance by excess current and energy passing through them.
+
+The inrush current of ICT equipment at interface P shall be tested by referring to [ETSI EN 300-132-3-1].
+
+**Appendix I**
+
+### **Information on grounding method**
+
+(This appendix does not form an integral part of this Recommendation.)
+
+**I.1 Basic configuration**
+
+All cabinets/chassis in the 'up to 400 VDC' system should have a protective earth (PE). A high resistance  $R_g$  connected between each power line and ground at the output section of the rectifier shall be neutral. By using  $R_g$ , the ground-fault current should be controlled to be less than 20 mA. A protective circuit, such as a fuse/circuit-breaker, should be installed in the positive and negative power lines because both poles of the power line have a  $V_o/2$  voltage to the ground level. (An example of the basic configuration is shown in Figure I.1.) Because of the necessity to ensure human safety, and due to the low level ground fault current, the power system should have a leakage current detector and an alarm function.
+
+![Figure I.1 – Example of the basic configuration of a grounding system for an 'up to 400 VDC' system](411fa16c3211377525ba37c57784fee0_img.jpg)
+
+A schematic diagram showing a DC power system. On the left is a 'Rectifier' block with (+) and (-) DC power output terminals. Two resistors  $R_g$  are connected in series between the (+) and (-) lines, with the center point connected to a common ground point. The voltage across each resistor is labeled  $V_o/2$ , and the total voltage is  $V_o$ . A 'Battery unit' is connected across the DC lines. To the right is a 'DC power distribution' block with fuses/circuit breakers on both lines. Finally, on the far right is 'ICT equipment' connected to the distribution. Protective Earth (PE) connections are shown for the rectifier, battery unit, distribution, and ICT equipment, all leading to a common ground. The interface between the distribution and ICT equipment is labeled 'Interface P'.
+
+Figure I.1 – Example of the basic configuration of a grounding system for an 'up to 400 VDC' system
+
+**Figure I.1 �� Example of the basic configuration of a grounding system for an 'up to 400 VDC' system**
+
+**I.2 Specification for PE at interface P**
+
+The power lines and PE ports (PE ports are connected to the metallic enclosure of the equipment on Figures I.1 and I.2) at interface P of the PSU should be isolated. To ensure protection against any stray current, the input and output power ports of the PSU should be isolated; namely, the power converter should be isolated e.g., by a transformer (see Figure I.2).
+
+![Figure I.2 – Grounding system configuration for an 'up to 400 VDC' system](b8261918596971c3801af23435c5ea50_img.jpg)
+
+A schematic diagram showing isolation within ICT equipment. On the left, 'Up to 400 V DC power feeding system' provides (+), (-), and PE lines. These enter the 'ICT equipment' at 'Interface P'. Inside the ICT equipment, there is an 'Isolation' boundary. The (+) and (-) lines enter a 'Power supply unit' which contains a transformer symbol, indicating electrical isolation between the input and output. The PE line is connected to the equipment's metallic enclosure but is shown as isolated from the internal power supply unit's secondary side.
+
+Figure I.2 – Grounding system configuration for an 'up to 400 VDC' system
+
+**Figure I.2 – Grounding system configuration for an 'up to 400 VDC' system**
+
+8 Rec. ITU-T L.1200 (05/2012)
+
+The safety, earthing and bonding should use ITU-T work and other standards from IEC and ETSI.
+
+In particular the use of interface P should maintain compliance with [b-IEC 60950-1].
+
+If there is a need for monitoring including alarms, the interface protocol might be based on [b-ETSI ES 202 336-1] and [b-ETSI ES 202 336-2].
+
+## Bibliography
+
+- [b-ETSI ES 202 336-1] EN 202 336-1 (in force), *Environmental Engineering (EE); Monitoring and Control Interface for Infrastructure Equipment (Power, Cooling and Building Environment Systems used in Telecommunication Networks) Part 1: Generic Interface.*
+- [b-ETSI EN 202 336-2] EN 202 336-2 (in force), *Environmental Engineering (EE); Monitoring and control interface for infrastructure equipment (Power, Cooling and environment systems used in telecommunication networks) Part 2: DC power system control and monitoring information model.*
+- [b-IEC 60950-1] IEC 60950-1 (2005), *Information technology equipment – Safety – Part 1: General requirements.*
+- [b-DC Distribution 2] Babasaki, T. *et al.*, (2010), *Developing of higher voltage direct-current power-feeding prototype system*, Telecommunications Energy Conference, INTELEC 2009, pp. 1-5, IEEE.
+- [b-Grounding concept] Hirose, K. *et al.*, (2011), *Grounding concept considerations and recommendations for 400 VDC distribution system*, Telecommunications Energy Conference (INTELEC), pp. 1-8, IEEE.
+- [b-DC Architecture] Marquet, D. and Kervarrec, G. (2005), *New Flexible Powering Architecture for Integrated Service Operators*, Telecommunications Conference, INTELEC '05, pp. 575-580, IEEE.
+- [b-DC Distribution 1] Pratt, A., Kumar, P. and Aldridge, T.V. (2007), *Evaluation of 400 VDC distribution in telco and data centers to improve energy efficiency*, Telecommunications Energy Conference, INTELEC 2007, pp. 32-39, IEEE.
+- [b-DC grounding] Tanaka, T. *et al.*, (2009), *Basic study on grounding system for high-voltage direct current power supply system*, Telecommunications Energy Conference, INTELEC 2009, pp. 1-4., IEEE.
+- [b-DC Fuse] Tanaka, T., Babasaki, T. and Mino, M. (2008), *Fuse blowing characteristics for HVDC power supply systems*, Telecommunications Energy Conference, INTELEC 2008, pp. 1-6, IEEE.
+- [b-DC Characteristics] Babasaki, T. *et al.*, (2010), *Basic Characteristics of New Developed Higher-Voltage Direct-Current Power-Feeding Prototype System*, IEICE Transactions on Communications Vol. E93-B No. 9 pp. 2244 2249.
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                |
+|-----------------|------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                              |
+| Series D        | General tariff principles                                                                      |
+| Series E        | Overall network operation, telephone service, service operation and human factors              |
+| Series F        | Non-telephone telecommunication services                                                       |
+| Series G        | Transmission systems and media, digital systems and networks                                   |
+| Series H        | Audiovisual and multimedia systems                                                             |
+| Series I        | Integrated services digital network                                                            |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals    |
+| Series K        | Protection against interference                                                                |
+| <b>Series L</b> | <b>Construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                            |
+| Series N        | Maintenance: international sound programme and television transmission circuits                |
+| Series O        | Specifications of measuring equipment                                                          |
+| Series P        | Terminals and subjective and objective assessment methods                                      |
+| Series Q        | Switching and signalling                                                                       |
+| Series R        | Telegraph transmission                                                                         |
+| Series S        | Telegraph services terminal equipment                                                          |
+| Series T        | Terminals for telematic services                                                               |
+| Series U        | Telegraph switching                                                                            |
+| Series V        | Data communication over the telephone network                                                  |
+| Series X        | Data networks, open system communications and security                                         |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks      |
+| Series Z        | Languages and general software aspects for telecommunication systems                           |

marked/L/T-REC-L.1301-201505-I_PDF-E/raw.md

@@ -0,0 +1,596 @@
+
+
+International Telecommunication Union
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**L.1301**
+
+(05/2015)
+
+SERIES L: CONSTRUCTION, INSTALLATION AND  
+PROTECTION OF CABLES AND OTHER ELEMENTS OF  
+OUTSIDE PLANT
+
+---
+
+**Minimum data set and communication interface  
+requirements for data centre energy  
+management**
+
+Recommendation ITU-T L.1301
+
+ITU-T
+
+![ITU logo: A globe with a red lightning bolt and the text 'ITU International Telecommunication Union'.](84a1d09fb489061482111515543b60dc_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features a stylized globe with a red lightning bolt striking across it. To the right of the globe, the text "ITU" is written in a bold, blue font, and below it, "International Telecommunication Union" is written in a smaller, blue font.
+
+ITU logo: A globe with a red lightning bolt and the text 'ITU International Telecommunication Union'.
+
+
+
+# Recommendation ITU-T L.1301
+
+# Minimum data set and communication interface requirements for data centre energy management
+
+## Summary
+
+Recommendation ITU-T L.1301 establishes a minimum data set necessary to manage data centres and telecommunication rooms in an environmentally responsible manner.
+
+The Recommendation specifies the communication interface and defines the parameters to be communicated depending on the equipment used in data centres, such as power systems (alternating current (AC)/direct current (DC) and uninterruptible power supply (UPS) and energy distribution), cooling systems and information and communication technology (ICT) equipment.
+
+## History
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T L.1301   | 2015-05-07 | 5           | <a href="http://handle.itu.int/11.1002/1000/12428">11.1002/1000/12428</a> |
+
+## Keywords
+
+Data centre, energy management.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2015
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+###### Page
+
+|       |                                                                                                     |    |
+|-------|-----------------------------------------------------------------------------------------------------|----|
+| 1     | Scope.....                                                                                          | 1  |
+| 2     | References.....                                                                                     | 1  |
+| 3     | Definitions .....                                                                                   | 1  |
+| 3.1   | Terms defined elsewhere .....                                                                       | 1  |
+| 3.2   | Terms defined in this Recommendation.....                                                           | 1  |
+| 4     | Abbreviations and acronyms .....                                                                    | 2  |
+| 5     | Conventions .....                                                                                   | 2  |
+| 6     | Architecture of data centre energy management .....                                                 | 2  |
+| 7     | Managed entities .....                                                                              | 3  |
+| 8     | General requirements for data centre energy management .....                                        | 3  |
+| 8.1   | Requirements for communication interfaces .....                                                     | 3  |
+| 8.2   | Requirements for measuring data .....                                                               | 4  |
+| 9     | Minimum data set for energy management in data centres .....                                        | 4  |
+| 9.1   | Minimum set of static data .....                                                                    | 4  |
+| 9.2   | Minimum set of dynamic data .....                                                                   | 5  |
+| 10    | Data definition and requirements.....                                                               | 6  |
+| 10.1  | Requirements for data items of ICT equipment .....                                                  | 6  |
+| 10.2  | Requirements for data items of facility equipment .....                                             | 7  |
+|       | Appendix I – Examples of an optional data set for energy management in a cloud data centre.....     | 8  |
+| I.1   | Managed entities.....                                                                               | 8  |
+| I.2   | Minimum data set .....                                                                              | 8  |
+|       | Appendix II – Examples of use cases for a minimum data set .....                                    | 10 |
+|       | Appendix III – Suggested accuracy value of measurement data .....                                   | 12 |
+| III.1 | ICT equipment.....                                                                                  | 12 |
+| III.2 | Cooling equipment .....                                                                             | 12 |
+| III.3 | Power equipment .....                                                                               | 12 |
+|       | Appendix IV – Related standardization activities in other standards development organizations ..... | 13 |
+| IV.1  | Activities in ETSI .....                                                                            | 13 |
+| IV.2  | Activities in ECMA .....                                                                            | 13 |
+| IV.3  | Activities in IETF .....                                                                            | 13 |
+|       | Bibliography.....                                                                                   | 14 |
+
+
+
+# Recommendation ITU-T L.1301
+
+## Minimum data set and communication interface requirements for data centre energy management
+
+## 1 Scope
+
+This Recommendation aims to:
+
+- establish a minimum data set necessary to manage data centres in an environmentally responsible manner;
+- establish high-level interface requirements for information and communication technology (ICT) and facility equipment communication that contribute to energy saving, energy management and energy-saving evaluation.
+
+## 2 References
+
+None.
+
+## 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+None.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 communication interface:** An interface through which the management system communicates with the facility equipment and ICT equipment.
+
+**3.2.2 data centre:** A physical location dedicated to computing, as well as a telecom operator location, with equipment dedicated to telecommunication functions (e.g., switching functionality, billing).
+
+**3.2.3 dynamic data:** Data that is periodically obtained from information and communication technology (ICT) equipment and facility equipment.
+
+**3.2.4 facility equipment:** Equipment that supports the information and communication technology (ICT) equipment (e.g., cooling systems and power feeding systems) used in data centres.
+
+**3.2.5 managed entity:** An entity, which is a part of an equipment, that is monitored and managed.
+
+**3.2.6 management system:** A system that collects dynamic/static data and also transmits control data through the communication interface for data centre energy management.
+
+**3.2.7 minimum data set:** A data set that shall be an essential and minimum set of data transmitted over the communication interface for data centre energy management.
+
+**3.2.8 sensor:** A device that transforms a physical value (e.g., temperature, current) into an electrical or logical unit. The sensor can be directly connected with a data stream to the management system or via a conversion device.
+
+**3.2.9 static data:** Data which is constant during operation, such as: specification, configuration and location information.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|      |                                          |
+|------|------------------------------------------|
+| AC   | Alternating Current                      |
+| CPU  | Central Processing Unit                  |
+| CRAC | Computer Room Air Conditioner            |
+| DC   | Direct Current                           |
+| ICT  | Information and Communication Technology |
+| ID   | Identifier                               |
+| PDU  | Power Distribution Unit                  |
+| THD  | Total Harmonic Distortion                |
+| UPS  | Uninterruptible Power Supply             |
+
+## 5 Conventions
+
+None.
+
+## 6 Architecture of data centre energy management
+
+Figure 1 illustrates the architecture of data centre energy management. It consists of information and communication technology (ICT) and facility equipment, which are managed entities, and a management system. General information on equipment called static data, is transmitted to the management system through a communication interface. Energy-related data from the managed entity should be periodically collected and delivered to the management system. The ICT and facility equipment monitors energy-related data, such as power usage and inlet temperature with an agent program or sensors and transmits them to the management system through a communication interface. The management system collects these dynamic data from the ICT and facility equipment and analyses them to produce effective information for energy-efficient data centres. The management system also transmits control data to manipulate the ICT and facility equipment to manage their energy usage through a communication interface. The requirements of the communication interface and data set from the managed entities are the scope of this Recommendation.
+
+![Diagram of data centre energy management architecture showing Management system, ICT equipment, and Facility equipment with data flows for static, dynamic, and control data.](07b17a620c75522d53916a11e12d1bff_img.jpg)
+
+The diagram illustrates the architecture of data centre energy management. At the top is a box labeled 'Management system' containing a database/storage icon. Below it are two boxes: 'ICT equipment' and 'Facility equipment'. Each of these boxes contains a 'Monitoring agent/sensor' (light grey rectangle) and a 'Controller' (dark grey rectangle). Arrows indicate data flow: 'Static data' from the monitoring agents/sensors to the management system, 'Dynamic data' from the monitoring agents/sensors to the management system, and 'Control data' from the management system to the controllers. A bracket on the right side, labeled 'Scope of this Recommendation', encompasses the dynamic and control data paths. A legend at the bottom identifies the icons: a cylinder for 'Database/storage', a light grey rectangle for 'Monitoring agent/sensor', and a dark grey rectangle for 'Controller'. The text 'L.1301(15)\_F01' is in the bottom right corner.
+
+Diagram of data centre energy management architecture showing Management system, ICT equipment, and Facility equipment with data flows for static, dynamic, and control data.
+
+**Figure 1 – Architecture of data centre energy management**
+
+## 7 Managed entities
+
+Managed entities for energy efficiency in data centres are categorized into ICT equipment and facility equipment. Managed entities in ICT equipment are server, storage and networking equipment. Facility equipment includes power feeding systems and cooling systems, which are infrastructures to support stable operation of data centres. The power feeding system includes a backup generator, rectifier, alternating current (AC) uninterruptible power supply (UPS), battery, power distribution unit (PDU), etc. The cooling system includes a chiller, cooling tower, economizer, computer room air conditioner (CRAC), modular cooling systems, humidifier, etc. These are the managed entities that should be identified and managed. Specification, configuration and location information on the managed entities are managed as static data. Operating data related to energy management such as energy consumption and temperature is periodically measured and managed as dynamic data. Table 1 shows managed entities for energy management in data centres.
+
+**Table 1 – Managed entities for energy management in data centres**
+
+| Equipment type     |                      | Managed entities                                                           |
+|--------------------|----------------------|----------------------------------------------------------------------------|
+| ICT equipment      |                      | Server equipment                                                           |
+|                    |                      | Storage equipment                                                          |
+|                    |                      | Networking equipment (e.g., switch, router)                                |
+| Facility equipment | Cooling system       | Chiller                                                                    |
+|                    |                      | Cooling tower                                                              |
+|                    |                      | Economizer                                                                 |
+|                    |                      | Air cooling unit                                                           |
+|                    |                      | Computer room air conditioner (CRAC)                                       |
+|                    |                      | Modular cooling systems (in-row, in-rack, in-chassis)                      |
+|                    |                      | Humidifier                                                                 |
+|                    |                      | Outdoor air system                                                         |
+|                    |                      | Heat exchanging system                                                     |
+|                    | Power feeding system | Backup generator                                                           |
+|                    |                      | Rectifier                                                                  |
+|                    |                      | Battery                                                                    |
+|                    |                      | Power distribution unit (PDU)                                              |
+|                    |                      | AC high/medium voltage power distribution system                           |
+|                    |                      | AC low voltage power distribution system                                   |
+|                    |                      | AC uninterruptible power supply (UPS)                                      |
+|                    |                      | AC/direct current (DC) converters (up to 400 V system, -48 V system, etc.) |
+|                    |                      | DC/AC inverter                                                             |
+|                    |                      | Other energy system                                                        |
+
+## 8 General requirements for data centre energy management
+
+### 8.1 Requirements for communication interfaces
+
+- Compatibility of communication interfaces should be provided in order to manage data collected from multivendor equipment in an identical way.
+
+- Data should be collected without loss and within allowable delay times through a communication interface.
+- Communication interfaces should provide a method to retain the integrity of collected data. Errors in data should be detected.
+- Communication interfaces should provide a method to gather dynamic data from a monitoring agent or sensors.
+- Communication interfaces and control data should be scalable to the number and size of items of equipment.
+- Communication interfaces and control data should be extensible to support various types of equipment, including multivendor solutions.
+
+### 8.2 Requirements for measuring data
+
+- Equipment should have a monitoring agent or sensors to gather dynamic data.
+- Equipment should hold static data and make it available to the management system.
+- Equipment should be uniquely identified also under a multivendor environment.
+- Dynamic and static data should have a unique identifier in view of the management system.
+- Data collected from equipment including multivendor solutions should consistently be maintained in the management system.
+- Data should have a specific form to be easily stored and processed in the management system.
+
+## 9 Minimum data set for energy management in data centres
+
+Data on data centre configuration (e.g., room layout) and facility connection to ICT equipment are stored in the management system.
+
+### 9.1 Minimum set of static data
+
+Data collected from equipment for energy management in data centres are about managed entities. Equipment identifiers (IDs), specifications and configurations for managed entities must be collected in order to manage operating and energy related information in data centres. Table 2 shows the minimum set of static data for energy management in data centres.
+
+**Table 2 – Minimum set of static data for energy management in data centres**
+
+| Equipment type    | Data set                                                                          |
+|-------------------|-----------------------------------------------------------------------------------|
+| ICT equipment     | Equipment ID and description                                                      |
+|                   | Operating temperature range                                                       |
+| Cooling equipment | Equipment ID and description                                                      |
+|                   | Energy consumption characteristics of devices used to cool the refrigerant        |
+|                   | Energy consumption characteristics of devices used to transport the refrigerant   |
+|                   | Presence or absence of the mode controlling the amount of refrigerant transported |
+|                   | Temperature setting range of refrigerant supplied from the indoor unit            |
+|                   | Temperature setting step size of refrigerant supplied from the indoor unit        |
+|                   | Rated amount of refrigerant supplied from the indoor unit                         |
+| Power equipment   | Equipment ID and description                                                      |
+|                   | Total capacity of generator, AC UPS and up to 400 V DC system                     |
+|                   | Number of battery strings and capacity of each battery string                     |
+|                   | Efficiency characteristics                                                        |
+
+### 9.2 Minimum set of dynamic data
+
+Dynamic data refers to data that is obtained from managed entities periodically for energy management in data centres. Table 3 lists the minimum data set necessary for evaluating energy efficiency and for controlling ICT and facility equipment in order to save power in data centres. "G" (Get) in the "Data flow direction" column represents data that should be obtained from equipment and "S" (Set) data represents data that should be set to equipment.
+
+**Table 3 – Minimum data set controlling ICT and facility equipment for energy saving management in data centres**
+
+| Equipment type     |  | Data set                                                                            | Data flow direction |
+|--------------------|--|-------------------------------------------------------------------------------------|---------------------|
+| ICT equipment      |  | Input power                                                                         | G                   |
+|                    |  | Inlet temperature                                                                   | G                   |
+|                    |  | Power state (off mode, sleep, active)                                               | G                   |
+|                    |  | Power state (off mode, activate)                                                    | S                   |
+| Facility equipment |  | Power state                                                                         | G/S (Note 2)        |
+|                    |  | Supply air temperature                                                              | G                   |
+|                    |  | Return air temperature                                                              | G                   |
+|                    |  | Outdoor air temperature                                                             | G                   |
+|                    |  | Temperature setting                                                                 | G/S (Note 1)        |
+|                    |  | Relative humidity                                                                   | G                   |
+|                    |  | Power consumption                                                                   | G                   |
+|                    |  | Energy consumption                                                                  | G                   |
+|                    |  | Fan speed                                                                           | G/S (Note 2)        |
+|                    |  | Output power                                                                        | G                   |
+|                    |  | Input power                                                                         | G                   |
+|                    |  | Input voltage input current of AC UPS/up to 400 V DC/ Inverter/ other energy system | G                   |
+|                    |  | Battery voltage charging/discharging current                                        | G                   |
+|                    |  | Total harmonic distortion (THD) of AC system input current                          | G (Note 3)          |
+|                    |  | AC system power factor                                                              | G                   |
+
+NOTE 1 – Temperature measure is normally taken from a sensor at room level and not inside an item of cooling equipment but is considered part of the cooling system.  
+NOTE 2 – Setting of this dataset is an optional functionality.  
+NOTE 3 – Optional information.
+
+## **10 Data definition and requirements**
+
+### **10.1 Requirements for data items of ICT equipment**
+
+#### **10.1.1 Measured parameters for energy management**
+
+The inlet temperature and input power of the ICT equipment shall be provided as measurement parameters.
+
+In energy management, it is necessary to maintain ICT equipment that operates under varying load conditions within a specified temperature range and to monitor how much energy the equipment consumes.
+
+ICT equipment generally has a number of embedded sensors placed in necessary locations. What measured data are collected or how the data are aggregated may depend on each operator's management applications, but the abovementioned parameters, aggregated in some cases, shall be provided as common parameters for monitoring and control. Precise location information of embedded sensors in the equipment is not necessarily required.
+
+#### **10.1.2 Common identification of measured parameters**
+
+The names and IDs of sensors used for measuring data parameters are assigned by equipment vendors. Thus, when monitoring the inlet temperature of equipment, for example, it is necessary to identify the sensor name (or ID) corresponding to the inlet temperature and to configure necessary settings for each piece of equipment. This adds unnecessary inconvenience and ineffectiveness to the management operations of many equipment resources.
+
+Each parameter corresponding to the inlet temperature and input power of equipment shall therefore have a common name and/or ID that are not dependent on vendors.
+
+#### **10.1.3 Measurement interval**
+
+For energy efficient operation of ICT equipment, related data should immediately be measured and collected. Considerations on setting the interval of measurement include the importance of timeliness of data, the performance of the measuring tool and the amount of measured data. For example, it is desirable to set a very short time interval of measurement when the data varies in time or the variation of the data in time is regarded as significant. On the other hand, if the data does not vary significantly in time or if the amount of measured data is high, it may be desirable to set a longer measurement interval.
+
+Real-time measuring is not always possible due to the features and limitations of equipment measuring tools. Even though measurement is carried out in a real-time manner, a management system may not collect or store measurements in the same way. For example, when a measuring tool measures and collects data every 30 seconds from ICT equipment, a management system may average the data out over 5 minutes or 1 hour.
+
+#### **10.1.4 Indication of allowable temperature range**
+
+The use of monitoring and control shall be applied in order to maintain the temperature environment of ICT equipment within an allowable range during its operation. Parameters of threshold value(s) shall be provided as information representing such a range. Examples of thresholds are "Non critical", "Critical", "Non recoverable", etc.
+
+#### **10.1.5 Measurement resolution and accuracy of the measurement data**
+
+The accuracy of measurement values depends on a sensor's capability, stability and location, i.e., whether the sensor is embedded or externally installed. The degree of precision necessary for these factors can be determined by the deployed ICT equipment specifications, management applications, and in a broader sense, the operator's management policy, capital costs and operational costs.
+
+The accuracy of measured data, however, is essential for ensuring effective monitoring and control. First, the "resolution" of inlet temperature and input power of equipment shall be provided as the fundamental measurement unit concerning accuracy. Here "resolution" represents the smallest scale unit measurable by the sensor. Second, it is required to keep an acceptable error range of measured data in order to provide effective energy management. Therefore, the "accuracy" shall be provided as an acceptable error range of measured data.
+
+### **10.2 Requirements for data items of facility equipment**
+
+#### **10.2.1 Measured parameters for energy management**
+
+For cooling equipment, the following parameters are fundamental to energy management. Parameters related to the air-conditioning capability that the cooling system handles include supply air temperature, return air temperature, outdoor air temperature, temperature setting and relative humidity. Power and energy related parameters of cooling equipment include power consumption, energy consumption as well as the power state of the cooling equipment itself.
+
+In addition, fan speed monitoring and control functionality may be necessary. For example, the use cases of coordinated energy management to reduce hot spots, shown in Appendix II, is to be one of the important best practices for data centres. For the power equipment, the input power and output power are fundamental to energy management.
+
+#### **10.2.2 Common identification of measured parameters**
+
+The names and IDs of sensors used for measuring data parameters are assigned by equipment vendors. Thus, when monitoring the return air temperature of cooling equipment, for example, it is necessary to identify the sensor name (or ID) corresponding to the return air temperature and to configure necessary settings for each piece of equipment. This adds unnecessary inconvenience and ineffectiveness to the management operations across multivendor environments.
+
+Each measured parameter shall therefore have a common name and/or ID that are not dependent on vendors.
+
+#### **10.2.3 Measurement resolution and accuracy of the measurement data**
+
+The accuracy of measured data is essential for ensuring effective monitoring and control. Firstly, the "resolution" of measurement parameters shall be provided as the fundamental measurement unit concerning accuracy. Here "resolution" represents the smallest scale unit measurable by the sensor. Secondly, it is required to keep an acceptable error range of measured data in order to provide effective energy management. Therefore, the "accuracy" shall be provided as an acceptable error range of measured data.
+
+Appendix III contains suggested values for accuracy of measurement data.
+
+## Appendix I
+
+## Examples of an optional data set for energy management in a cloud data centre
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Appendix I is intended to present an optional data set for energy management of a cloud data centre. A cloud data centre is understood herein as a data centre used to provide mainly "cloud computing" platforms and services. The term "cloud computing" is a paradigm for enabling network access to a scalable and elastic pool of shareable physical or virtual resources with on-demand self-service provisioning and administration, for more information, see [b-ITU-T Y.3500].
+
+In a cloud data centre, ICT equipment can be virtualized and integrated into fewer systems according to resource utilization. For example, after analysing the relationship between central processing unit (CPU) utilization and the energy consumption of servers, it may be helpful to integrate distributed workloads in servers with low utilization into fewer servers for energy efficient management. For this purpose, not only the specifications of the CPU, disk and network interfaces but also their operating data should be monitored and managed.
+
+### I.1 Managed entities
+
+Managed entities in cloud data centres include server, storage and network equipment. The CPU, disk and network interface whose workload (utilization) can be measured should be included in managed entities for energy management in cloud data centres. The CPU can be a managed entity for the server and the disk can be a managed entity for storage. Networking equipment such as a switch and a router can be composed of a common chassis with line cards and ports. Thus, chassis, line cards and ports in networking equipment can be a managed entity. Table I.1 shows managed entities for energy management in cloud data centres.
+
+**Table I.1 – Managed entities for energy management in cloud data centres**
+
+| Equipment type | Managed entities     |                                              |
+|----------------|----------------------|----------------------------------------------|
+| ICT equipment  | Server equipment     | CPU                                          |
+|                | Storage equipment    | Disk                                         |
+|                | Networking equipment | Chassis, line card, port (network interface) |
+
+### I.2 Minimum data set
+
+#### I.2.1 Minimum set of static data
+
+The minimum set of static data for energy management in cloud data centres relates to the configuration and specifications of ICT equipment. Server specification may include the number of CPUs, the number of cores and clock rate. Storage specification may include the total capacity of disks in the storage equipment. Networking equipment specification may include configurations of chassis, line cards and ports and the bandwidth (transmission rate) of network interfaces.
+
+**Table I.2 – Minimum set of static data for energy management in cloud data centres**
+
+| <b>Equipment type</b> | <b>Data</b>                        | <b>Data flow direction</b> |
+|-----------------------|------------------------------------|----------------------------|
+| ICT equipment         | Server specification               | G                          |
+|                       | Storage specification              | G                          |
+|                       | Networking equipment specification | G                          |
+
+#### **I.2.2 Minimum set of dynamic data**
+
+The energy efficiency of cloud data centres could be improved if IT resource utilization is periodically collected and utilized for integrating many systems with low workloads into a few systems with high workloads. For this purpose, CPU utilization, disk utilization and network interface utilization in network equipment should be included in the minimum set of dynamic data as shown in Table I.3.
+
+**Table I.3 – Minimum set of dynamic data for energy management in cloud data centres**
+
+| <b>Equipment type</b> | <b>Data set</b>               | <b>Data flow direction</b> |
+|-----------------------|-------------------------------|----------------------------|
+| ICT equipment         | CPU utilization               | G                          |
+|                       | Disk utilization              | G                          |
+|                       | Network interface utilization | G                          |
+
+## Appendix II
+
+## Examples of use cases for a minimum data set
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Examples of use cases for a minimum data set are shown in Figure II.1.
+
+- Monitoring the temperature and power of ICT and facility equipment
+
+To achieve energy saving in a data centre, it is necessary to collect ambient information such as floor temperature distribution and power usage of ICT equipment. As shown in use case 1 of Figure II.1, energy management systems are considered to be capable of detecting hot and cold spots, improving CRAC operation and of analysing the power-usage trends of each piece of equipment by collecting the necessary ambient information from ICT and facility equipment. The inlet temperature, power usage and power state of ICT equipment are examples of dynamic data to be collected. In addition, to maintain ICT equipment within the allowable temperature range, the threshold inlet temperature of ICT equipment can be considered as an example of static data to be collected.
+
+- Coordinated control of multiple cooling units
+
+It is important that cooling units can be managed appropriately to operate ICT equipment in the data centre with stability in the appropriate temperature environment. Currently in many data centres, multiple ambient type cooling units are installed for cooling entire computer floors and these cooling units are generally controlled individually and autonomously.
+
+The concept of coordinated control of multiple cooling units is shown in use case 2 of Figure II.1.
+
+The left part of use case 2 shows a case in which multiple cooling units are operated at a uniform temperature setting in a machine room with heat load deviation. In this case, hot spots occur locally in the area with a large heat load and the environment temperature cannot be maintained properly. In addition, cold spots occur locally in areas with a small heat load and the power of cooling units is consumed ineffectively.
+
+With the issues mentioned above, the right part of use case 2 shows a solution in which multiple cooling units with individual and dynamic temperature settings and the fan mode for each cooling unit are properly controlled by the management system.
+
+To make such coordinated control possible, it is required that the management system collects the following dynamic data:
+
+- ICT equipment: inlet temperature, power consumption and power state,
+- Cooling unit: power state, temperatures (return air, supply air and outside air), temperature setting, frequency of fan, operational mode (normal operation mode, protected operation mode), power consumption and energy consumption.
+
+It is also required that the management system controls the following parameters.
+
+- Cooling unit: temperature setting.
+
+![Diagram illustrating two use cases for a minimum data set in a data center. Use case #1: Monitoring of temperature and power consumption of data centre equipment. Use case #2: Coordinated control of multiple cooling units. The diagram shows a Management system connected to ICT equipment and Cooling units via Monitoring and Control paths.](8fbdfc3d17fb1dae7b2d8f5a287fa9fc_img.jpg)
+
+**Use case #1: Monitoring of temperature and power consumption of data centre equipment**
+
+- Detection of hot spots and overcooling
+- ⇒ Review of cooling strategy
+- Analysis of power consumption trend
+
+**Use case #2: Coordinated control of multiple cooling units**
+
+- Adjusting cooling output among units
+- ⇒ Prevention of hot spots and overcooling
+- ⇒ Efficient cooling and energy saving
+
+**Management system**
+
+**Monitoring**
+
+**Control**
+
+**ICT equipment**
+
+**Cooling units**
+
+**Equipment ID**  
+Power state  
+Supply air temperature  
+Return air temperature  
+Outdoor air temperature  
+Temperature setting  
+Fan frequency  
+Operational mode  
+Power consumption
+
+**Equipment ID**  
+Power state  
+Inlet temperature  
+Temperature threshold  
+Power consumption
+
+**Temperature setting**
+
+L.1301(15)\_FII.1
+
+Diagram illustrating two use cases for a minimum data set in a data center. Use case #1: Monitoring of temperature and power consumption of data centre equipment. Use case #2: Coordinated control of multiple cooling units. The diagram shows a Management system connected to ICT equipment and Cooling units via Monitoring and Control paths.
+
+**Figure II.1 – Examples of use cases for a minimum data set**
+
+## Appendix III
+
+## Suggested accuracy value of measurement data
+
+(This appendix does not form an integral part of this Recommendation.)
+
+### III.1 ICT equipment
+
+Suggested accuracies of measurement data of ICT equipment may be:
+
+For input power:  $\pm 3\%$  from 25% to 100% load and  $\pm 5\%$  below 25% load
+
+For inlet temperature:  $\pm 1^\circ\text{C}$  in the range of  $20\text{-}50^\circ\text{C}$
+
+As a means for ICT equipment to achieve required accuracy, the following can be considered.
+
+Employing sensor hardware with required accuracy
+
+Executing some software processes on measurement data (e.g., calculating a mean value of multiple sensors data)
+
+### III.2 Cooling equipment
+
+Suggested accuracies of measurement data of cooling equipment may be:
+
+For air temperature:  $\pm 0.5^\circ\text{C}$  in the range of  $20\text{-}50^\circ\text{C}$
+
+For relative humidity:  $\pm 5\%$
+
+For power consumption:  $\pm 2\%$
+
+For energy consumption:  $\pm 2\%$
+
+### III.3 Power equipment
+
+Suggested accuracies of measurement data of power equipment may be:
+
+For voltage:  $\pm 1\%$
+
+For current: AC current  $\pm 1\%$ , DC current  $\pm 5\%$
+
+## Appendix IV
+
+## Related standardization activities in other standards development organizations
+
+(This appendix does not form an integral part of this Recommendation.)
+
+Other standardizing organizations and initiatives study and address energy management aspects of facility and ICT equipment at telecommunication and data centre sites.
+
+### IV.1 Activities in ETSI
+
+[b-ETSI ES 300 202 336-1] defines a generic interface that applies to monitoring and control of the infrastructure environment, i.e., power, cooling and building environment systems for telecommunication centres. Further, [b-ETSI ES 300 202 336-12], as a related document series, is under development. This applies to a monitoring and control interface for telecom/ICT equipment power, energy and environmental parameters in telecommunication or data centres or customer premises.
+
+It discusses measurement both inside and outside of equipment, metrics and conditions such as input voltages and currents of equipment, air temperature and humidity at inlets and precision and accuracy, for larger and more complex sites that have many types of equipment provided by different manufacturers.
+
+### IV.2 Activities in ECMA
+
+[b-ECMA-400] describes modelled resources by using common information models (CIMs) of IT and facility equipment, systems and components in a data centre.
+
+IT systems refer mainly to computer systems and facility equipment refers to cooling systems. The energy management aspect of computer systems deals with properties of the input power and detailed power statuses.
+
+### IV.3 Activities in IETF
+
+[b-IETF RFC 7326] defines an energy management framework for devices within or connected to communication networks. The devices, or components of these devices (such as router line cards, fans and disks), can then be monitored and controlled. [b-IETF RFC 6988] defines requirements. [b-IETF RFC 7461] and [b-IETF RFC 7460] provide energy management related management information base (MIB) information to cover energy management functionality that is not covered by the Telecommunications Management Network model.
+
+Energy management objects applied to network equipment include, for example, measured power, measurement caliber (actual/estimated/presumed), power consumption over a certain interval, unit multiplier and accuracy. In addition, relationships are provided as powered by/powering, metered by/metering and aggregated by/aggregating.
+
+## Bibliography
+
+- [b-ITU-T Y.3500] Recommendation ITU-T Y.3500 (2014), *Information technology – Cloud computing – Overview and vocabulary.*
+- [b-ETSI ES 202 336-1] ETSI ES 202 336-1 (2011), *Environmental Engineering (EE); Monitoring and Control Interface for Infrastructure Equipment (Power, Cooling and Building Environment Systems used in Telecommunication Networks) Part1: Generic Interface.*
+- [b-ETSI ES 202 336-12] ETSI ES 202 336-12 (2015), *Environmental Engineering (EE); Monitoring and control interface for infrastructure equipment (power, cooling and building environment systems used in telecommunication networks); Part 12: ICT equipment power, energy and environmental parameters monitoring information model.*
+- [b-IETF RFC 6988] IETF RFC 6988 (2013), *Requirements for Energy Management.*
+- [b-IETF RFC 7326] IETF RFC 7326 (2014), *Energy Management Framework.*
+- [b-IETF RFC 7460] IETF RFC 7460 (2015), *Monitoring and Control MIB for Power and Energy.*
+- [b-IETF RFC 7461] IETF RFC 7461 (2015), *Energy Object Context MIB.*
+- [b-ECMA-400] ECMA-400 (2013), *Smart Data Centre Resource Monitoring and Control.*
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | General tariff principles                                                                                                                                        |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Terminals and subjective and objective assessment methods                                                                                                        |
+| Series Q        | Switching and signalling                                                                                                                                         |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects and next-generation networks                                                                        |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

marked/L/T-REC-L.1307-202403-I_PDF-E/raw.md

@@ -0,0 +1,400 @@
+
+
+# Recommendation **ITU-T L.1307 (03/2024)**
+
+SERIES L: Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant
+
+Energy efficiency, smart energy and green data centres
+
+---
+
+# **Energy efficiency in micro data centres for edge computing**
+
+![ITU logo](0538daaa5583c23e17db3a12f2281a55_img.jpg)
+
+The logo of the International Telecommunication Union (ITU) is located in the bottom right corner. It features the letters "ITU" in a bold, blue, sans-serif font, superimposed on a stylized globe icon with intersecting lines.
+
+ITU logo
+
+## ITU-T L-SERIES RECOMMENDATIONS
+
+### **Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant**
+
+|                                                               |                      |
+|---------------------------------------------------------------|----------------------|
+| OPTICAL FIBRE CABLES                                          | L.100-L.199          |
+| Cable structure and characteristics                           | L.100-L.124          |
+| Cable evaluation                                              | L.125-L.149          |
+| Guidance and installation technique                           | L.150-L.199          |
+| OPTICAL INFRASTRUCTURES                                       | L.200-L.299          |
+| Infrastructure including node elements (except cables)        | L.200-L.249          |
+| General aspects and network design                            | L.250-L.299          |
+| MAINTENANCE AND OPERATION                                     | L.300-L.399          |
+| Optical fibre cable maintenance                               | L.300-L.329          |
+| Infrastructure maintenance                                    | L.330-L.349          |
+| Operation support and infrastructure management               | L.350-L.379          |
+| Disaster management                                           | L.380-L.399          |
+| PASSIVE OPTICAL DEVICES                                       | L.400-L.429          |
+| MARINIZED TERRESTRIAL CABLES                                  | L.430-L.449          |
+| E-WASTE AND CIRCULAR ECONOMY                                  | L.1000-L.1199        |
+| POWER FEEDING AND ENERGY STORAGE                              | L.1200-L.1299        |
+| <b>ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES</b> | <b>L.1300-L.1399</b> |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES         | L.1400-L.1499        |
+| ADAPTATION TO CLIMATE CHANGE                                  | L.1500-L.1599        |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES               | L.1600-L.1699        |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                           | L.1700-L.1799        |
+
+*For further details, please refer to the list of ITU-T Recommendations.*
+
+# Recommendation ITU-T L.1307
+
+# Energy efficiency in micro data centres for edge computing
+
+## Summary
+
+With the advent of the artificial intelligence era, the demands for edge computing to provide ultra-low latency for various services that require high computation power continue to grow. The demand for micro data centres, an essential item of equipment for delivering edge computing services near users, is also growing. Recommendation ITU-T L.1307 presents considerations on micro data centres for edge computing services in energy efficiency aspects. In addition, it presents the management information needed to manage micro data centres' energy efficiency and provides a metric for evaluating the energy performance of micro data centres. Finally, it presents energy efficiency issues in the operation of edge computing services and methods to address them.
+
+## History\*
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID          |
+|---------|----------------|------------|-------------|--------------------|
+| 1.0     | ITU-T L.1307   | 2024-03-08 | 5           | 11.1002/1000/15767 |
+
+## Keywords
+
+Edge computing, energy efficiency, energy efficiency indicator, management, micro data centre.
+
+---
+
+\* To access the Recommendation, type the URL <https://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+## NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2024
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                            | Page |
+|----------------------------------------------------------------------------|------|
+| 1 Scope.....                                                               | 1    |
+| 2 References.....                                                          | 1    |
+| 3 Definitions .....                                                        | 1    |
+| 3.1 Terms defined elsewhere .....                                          | 1    |
+| 3.2 Terms defined in this Recommendation.....                              | 1    |
+| 4 Abbreviations and acronyms .....                                         | 2    |
+| 5 Conventions .....                                                        | 2    |
+| 6 Overview of edge computing and micro data centres .....                  | 2    |
+| 7 Considerations on micro data centre for edge computing .....             | 3    |
+| 8 Energy-efficient management of micro data centre.....                    | 4    |
+| 9 Energy-Efficient Indicator for micro data centre.....                    | 6    |
+| 10 Energy efficiency in edge computing .....                               | 7    |
+| Appendix I – Applying renewable energy to micro data centres.....          | 10   |
+| I.1 Recommended renewable energy types .....                               | 10   |
+| I.2 Photovoltaic power plant requirements for micro data centres .....     | 10   |
+| I.3 Method to incorporate the PV power plant with micro data centres ..... | 10   |
+| Bibliography.....                                                          | 12   |
+
+
+
+# Recommendation ITU-T L.1307
+
+# Energy efficiency in micro data centres for edge computing
+
+## 1 Scope
+
+This Recommendation describes considerations for improving the energy efficiency of micro data centres, which are essential items of equipment for edge computing services, and how to operate them efficiently from an energy perspective. In this respect, this Recommendation focuses on:
+
+- Considerations on micro data centres for edge computing: deployment, configuration including redundancy and components;
+- Energy efficiency in micro data centres: management functions including energy efficiency and operation perspective;
+- Energy efficiency in edge computing: management functions including energy efficiency and operation perspective.
+
+## 2 References
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+[ISO/IEC 30134-2] ISO/IEC 30134-2:2016, *Information technology – Data centres – Key performance indicators – Part 2: Power usage effectiveness (PUE)*.
+
+[ISO/IEC 30134-5] ISO/IEC 30134-5:2017, *Information technology – Data Centres – Key performance indicators – Part 5: IT Equipment utilization for servers (ITEU<sub>sv</sub>)*.
+
+# 3 Definitions
+
+### 3.1 Terms defined elsewhere
+
+This Recommendation uses the following terms defined elsewhere:
+
+**3.1.1 edge computing** [b-ITU-T Y.3073]: This refers to a strategy to deploy processing capability at network edge where end terminals are connected, and to perform the processing of data which is derived from and fed to the end terminals.
+
+**3.1.2 power usage effectiveness (PUE)** [ISO/IEC 30134-2]: Ratio of the data centre total energy consumption to information technology equipment energy consumption, calculated, measured or assessed across the same period.
+
+### 3.2 Terms defined in this Recommendation
+
+This Recommendation defines the following terms:
+
+**3.2.1 micro data centre energy efficiency indicator**: A metric used to assess and quantify the energy efficiency of a micro data centre.
+
+NOTE – This metric can be calculated based on the relation of server central processing unit (CPU) utilization and PUE.
+
+**3.2.2 micro data centre:** A solution designed to provide processing, storage and networking capabilities in a more compact and modular form.
+
+NOTE 1 – This solution is used in edge data centres; see [b-ITU-T L.1306].
+
+NOTE 2 – Micro data centres are typically deployed to address specific needs such as edge computing, where computing resources are placed closer to where data is generated or needed. This can improve performance, reduce latency and enhance overall efficiency for applications that require real-time processing or low-latency communication.
+
+**3.2.3 Offloading:** The process of transferring an application from a device with limited computation resources to one or more remote devices with more resources.
+
+## 4 Abbreviations and acronyms
+
+This Recommendation uses the following abbreviations and acronyms:
+
+|                    |                                                     |
+|--------------------|-----------------------------------------------------|
+| CPU                | Central Processing Unit                             |
+| EEI <sub>MDC</sub> | Energy Efficiency Indicator for a Micro Data Centre |
+| ITEU <sub>sv</sub> | IT Equipment Utilization for servers                |
+| MDC                | Micro Data Centre                                   |
+| PDU                | Power Distribution Unit                             |
+| PUE                | Power Usage Effectiveness                           |
+| PV                 | Photovoltaic                                        |
+| UPS                | Uninterruptible Power Supply                        |
+
+## 5 Conventions
+
+None.
+
+# 6 Overview of edge computing and micro data centres
+
+Emerging services such as autonomous vehicles, artificial intelligence and augmented reality require high-performance computing power and ultra-low latency. Cloud computing has high-performance computing resources, but it is far from user terminals that require services, which inevitably causes transmission delays. This has led to the emergence of edge computing, which can provide computing resources at the edge of the network closer to the users. By offloading tasks from the user terminal to edge computing, it is possible to use high-performance computing resources as well as to extend the battery life of the user terminal.
+
+The advantages provided by edge computing are as follows. Since computing resources are provided closer to the user, transmission delay can be reduced, and the service provisioning time can be shortened. It does not use cloud computing in the network core, so it does not consume network bandwidth in the core. It is easy to use location-based services or network context information because computing services are provided at the base station or on the premises where the user is located. However, there may be a lack of usable computing resources, in contrast to those available to cloud computing, so offloading to nearby edge computing or cloud computing in the core may be necessary.
+
+Edge computing aims to provide the computing resources required by a user terminal near the user's location, but the location of actual edge computing equipment may vary depending on service providers. A micro data centre can provide computing resources for edge computing services. Micro data centres are typically deployed to address specific needs such as edge computing, where computing resources are placed closer to the location where data is generated or needed. This can improve performance, reduce latency and enhance overall efficiency for applications that require real-
+
+time processing or low-latency communication. A micro data centre is a smaller or containerized data centre that is designed to provide processing, storage and networking capabilities in a more compact and modular form.
+
+Depending on the deployment location, there are restrictions on the operation and management of the micro data centre, including service quality such as delay, energy consumption, network bandwidth consumption and rental fee. Figure 1 shows possible locations of micro data centres for edge computing services. The closest location to users is achieved by deploying a micro data centre to Wi-Fi apps in homes or public places. Micro data centres can be deployed in corporate premises such as enterprises or smart factories to provide their own edge computing services. In the case of mobile network operators, micro data centres can be deployed in base stations. Depending on the coverage of the base station, it is possible to provide edge computing services in a smaller unit by placing it in a small cell of about 1 km or by placing it in a femtocell or picocell in a building. It is also possible to deploy micro data centres in base stations (eNodeB, gNodeB) that cover macro cells in a range of several kilometres. These options may depend on the service strategy provided by the edge computing provider.
+
+![Diagram illustrating the location of micro data centres (MDC) for edge computing. The diagram shows various network components connected to a central 'Multi-tech cell aggregation site'. On the left, a 'WiFi AP', 'On-premise' base station, and 'Small cell BS' are connected. On the right, a 'Macro cell BS (eNB or gNB)' is connected. The 'Multi-tech cell aggregation site' is connected to the 'Internet' cloud, which is further connected to a 'Cloud' server. A dashed box labeled 'Micro data centre (MDC)' is shown separately, indicating its potential deployment location.](562f471e8153729557e6a4ee6343c32c_img.jpg)
+
+The diagram illustrates the network architecture for edge computing. At the top left, a 'WiFi AP' (represented by a router icon) is connected to a 'Multi-tech cell aggregation site' (represented by a tower icon). Below the WiFi AP, an 'On-premise' base station (tower icon) and a 'Small cell BS' (tower icon) are also connected to the aggregation site. The aggregation site is connected to the 'Internet' cloud (represented by a cloud icon), which in turn is connected to a 'Cloud' server (represented by a server rack icon). A 'Macro cell BS (eNB or gNB)' (tower icon) is connected to the aggregation site. A dashed box labeled 'Micro data centre (MDC)' (represented by a server rack icon) is shown separately, indicating its potential deployment location. The diagram is labeled 'L.1307(24)' in the bottom right corner.
+
+Diagram illustrating the location of micro data centres (MDC) for edge computing. The diagram shows various network components connected to a central 'Multi-tech cell aggregation site'. On the left, a 'WiFi AP', 'On-premise' base station, and 'Small cell BS' are connected. On the right, a 'Macro cell BS (eNB or gNB)' is connected. The 'Multi-tech cell aggregation site' is connected to the 'Internet' cloud, which is further connected to a 'Cloud' server. A dashed box labeled 'Micro data centre (MDC)' is shown separately, indicating its potential deployment location.
+
+Figure 1 – Location of micro data centres for the realization of edge computing
+
+# 7 Considerations on micro data centre for edge computing
+
+If a micro data centre is placed in a dedicated space such as a traditional data centre, there is not much to consider from an energy efficiency perspective. However, additional considerations arise as the location of micro data centres may vary depending on edge computing service providers and their applications. Depending on edge computing service providers, the micro data centre can be placed in a general office, a communication room, a base station site, a central office, etc. It can be placed inside the building, or it can be placed outside the building depending on the policy of the operating company. When a micro data centre is placed in a non-dedicated space such as a general office or a commercial building, there are restrictions on the noise and vibration it causes. In order to supply stable power, an intelligent power distribution device and an uninterruptible power supply (UPS) are necessary. The capacity of the UPS must be calculated to continuously supply power to servers until it is replaced with an alternative power source in the event of a power outage. When a micro data
+
+centre is placed in a general building supplied by commercial power, it is necessary to ensure that sufficient power is supplied for the operation of the micro data centre and the building. It is recommended to separate the electrical power distribution for the micro data centre and the office. Since a cooling system for thermal control of servers is not provided in general office spaces, a cooling system should be equipped with a micro data centre. A management system (or software) for the data centre is necessary to manage computing resources and measure energy efficiency. Micro data centres deployed outdoors require strong physical security devices to protect against external intrusion. Table 1 summarizes the general requirements for micro data centres for edge computing.
+
+**Table 1 – Requirements for micro data centres for edge computing**
+
+| Category                        | General requirements                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
+|---------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Power supply                    | The power supply shall be configured in consideration of the maximum power that can be consumed by the servers, storages, network equipment, cooling system and other security and operation equipment constituting the micro data centre. It is recommended to separate electrical power distribution between the data centre and other service present in the site.                                                                                                                                                                                                                                                     |
+| Redundancy                      | Possible failures include server failure, storage and network equipment failure, cooling system failure, power outage and power supply failure. Backup servers in a rack can be used to protect against server failures or servers operated by other micro data centres can be used as backups through task offloading. UPS should be fitted to prepare for power outages. It is desirable to provide the battery capacity of the UPS to provide a backup time of 5–10 minutes to protect from power outage; protection from power failure can be implemented using UPS and power distribution system in redundancy mode. |
+| Virtualization                  | Since the main characteristic of edge computing technology is to process the computing of the user terminal instead, all computing resources in the micro data centre should be provided through virtualization. It is required to provide computing resources through virtual machines or container technology, network function virtualization and software-defined networking.                                                                                                                                                                                                                                         |
+| Computing capacity planning     | It is necessary to expand the capacity of computing resources as service demands from users increase. It is possible to expand computing resources from virtual machines to server units and up to rack units. In the case of the expansion of rack units, the power capacity of the building in which it is located should also be considered. Before physical expansion, computing offloading to a nearby micro data centre or a central cloud data centre is recommended.                                                                                                                                              |
+| Operation and management system | A management system is required to monitor environmental conditions such as temperature and humidity, and the operational status of computing resources and power consumption in order to optimize the operating condition.                                                                                                                                                                                                                                                                                                                                                                                               |
+| Noise and vibration             | If a micro data centre is placed in a general office (indoor), it is recommended that noise and vibration that the micro data centre causes not hinder the normal working for workers in the same place. If a micro data centre is placed outside, the restriction of noise and vibration can be relaxed. It is necessary to introduce an enclosed rack enclosure for noise and vibration reduction.                                                                                                                                                                                                                      |
+| Physical security               | When a micro data centre is placed in a general office building rather than a dedicated place in a data centre, it could be easily accessible to the general public. Thus, it requires strong physical security and access-limiting technologies.                                                                                                                                                                                                                                                                                                                                                                         |
+
+## 8 Energy-efficient management of micro data centre
+
+Micro data centres should be managed in the aspects of computing resources and energy consumption. IT-related resources such as servers, storage and networks should be managed to immediately provide computing resources to users who request edge computing services. Server virtualization or container technology can be applied for the efficient management of physical server resources. For this purpose,
+
+the utilization of server CPU, memory and storage should be monitored and managed. If the resources of the micro data centre are insufficient to provide the computing resources that users request, they can offload the computing resource to a nearby micro data centre or to cloud computing. Computing resources and facilities that the micro data centre should monitor and manage are presented in Table 2.
+
+Energy consumption and power saving are important management issues in micro data centres. So, it is necessary to periodically collect power consumed by various equipment in the micro data centre. It is very important to effectively remove the heat generated by the servers. This is for the stable operation of the servers as well as power saving of the cooling system. Therefore, it is necessary to collect temperature data in the data centre and operate the cooling system in an energy-efficient way. Table 2 additionally shows the data to be collected for energy management. These can be used to evaluate the energy efficiency of the micro data centre.
+
+**Table 2 – Resource items for energy-efficient managing micro data centres**
+
+| <b>Equipment</b> | <b>Managed data</b>                                                           | <b>Computing resources related data</b>                    | <b>Energy consumption related data</b>                        |
+|------------------|-------------------------------------------------------------------------------|------------------------------------------------------------|---------------------------------------------------------------|
+| Server           | Location, years, spec. (CPU, memory, disks, etc.)                             | Physical/virtual server CPU, memory, disk, I/O utilization | Energy consumption, temperature                               |
+| Storage          | Location, years, spec. (storage capacity)                                     | Storage utilization                                        | Energy consumption, temperature                               |
+| Network          | Location, years, spec. (bandwidth, ports, protocols, etc.), IP address, cable | Port utilization                                           | Energy consumption                                            |
+| Rack             | Rack ID (incl. location), server/storage/network configuration                |                                                            | Slots/ports used information, energy consumption, temperature |
+| Service          | Service list (service periods, used resources, on-/offload, users, etc.)      | Resource utilization per service                           |                                                               |
+| Power supply     | Power system capacity (PDU, UPS)                                              |                                                            | Energy consumption (input/output)                             |
+| Cooling system   | Cooling capacity                                                              |                                                            | Energy consumption                                            |
+| Others           | Security systems (camera, etc.)                                               |                                                            | Energy consumption                                            |
+
+A management system for micro data centres can be built in on-site or a remote place. The on-site management system can be accessed by a manager on the spot to monitor the current state of computing resources and energy consumption in the micro data centre. If a manager is in a remote location, the micro data centre can be operated and managed by remote access through the Internet. A management system can monitor and manage more than one micro data centre. A micro data centre manager could coordinate the computing resources in several micro data centres for task offloading.
+
+The basic principle of task offloading is to provide the resources of other edge computing to accommodate the needs of users who exceed the capacity of edge computing. However, from an energy point of view, if energy consumption is excessive in one micro data centre, it may choose to offload tasks to another micro data centre with lower energy consumption, consequently the overall energy consumption of all micro data centres could be minimized. Therefore, the management system of the micro data centre should not be limited to simply managing computing resources, but should also be managed in terms of energy consumption at the same time.
+
+# 9 Energy-Efficient Indicator for micro data centre
+
+For evaluating the energy efficiency of a data centre, Power Usage Effectiveness (PUE) is widely used as a performance indicator. PUE is the ratio of total power consumed in the data centre to the power consumed by IT equipment [ISO/IEC 30134-2]. It shows how much additional power is required to provide IT services. However, micro data centres may not have a backup power supply or cooling system to a similar level to the typical data centre, so this indicator should not be used as it is.
+
+To measure the energy efficiency of micro data centres, both the power consumed in a micro data centre and the utilization of servers in the data centres are considered. These two factors are used in performance indicators for the following reasons. Energy efficiency can be achieved by fundamentally reducing the power consumed in the data centre. According to Beloglazov et al. [b-Beloglazov], the server consumes minimum energy even in an idle state, and power consumption increases linearly as the server utilization rate increases as follows.
+
+$$P(u) = kP_{\max} + (1 - k)P_{\max} \cdot u \quad (1)$$
+
+$P_{\max}$  the maximum power consumed at a server utilization of 100%;
+
+$K$  the fraction of power consumed by the idle server;
+
+$u$  the CPU utilization of the server.
+
+Therefore, it is better in terms of energy efficiency to integrate and operate several tasks on a small number of servers using virtualization technology rather than to operate a large number of servers that are driven at low utilization rates. That is, the higher the average utilization rate of the servers and the lower the power consumption of the servers, the higher the energy efficiency of the micro data centre.
+
+Considering these points, the performance indicator for energy efficiency of a micro data centre should consider both the server utilization and the power consumption. The server utilization in a micro data centre can be obtained from IT Equipment Utilization for servers ( $ITEU_{sv}$ ) [ISO/IEC 30134-5].  $ITEU_{sv}$  describes the average CPU utilization of the servers in a data centre. The average CPU utilization of the servers at time  $t$  in a micro data centre can be described by
+
+$$ITEU_{sv}(t) = \sum_{i=1}^N \frac{U_i(t)}{N} \quad (2)$$
+
+$U_i(t)$  CPU utilization rate of server  $i$  at time  $t$ ;
+
+$N$  the number of running servers in a micro data centre at time  $t$ .
+
+Since the CPU utilization of a server and the running servers change over time,  $ITEU_{sv}$  should be monitored and measured at a specific time interval during a given measurement period, for example, a year. The maximum value of  $ITEU_{sv}(t)$  should be used at every measurement time interval.  $ITEU_{sv}$  is a metric for server based on CPU utilization, so it does not apply to storage systems or network equipment in a data centre. More detailed and specific method for calculating  $ITEU_{sv}$  can be found in [ISO/IEC 30134-5].
+
+If multiple servers with low utilization are integrated into a small number of servers using server virtualization technology, the  $ITEU_{sv}$  value will increase. As a result, power consumption in micro data centres is also expected to decrease. If the amount of power consumed by infrastructure facilities such as power supply and cooling equipment decreases in proportion to the amount of power saved by the server, PUE, which is widely used as a data centre performance indicator, can reveal the power saving effect well, but otherwise may not show the effectiveness of server consolidation. Therefore, the following performance indicator can be used to show energy efficiency in microdata centres in consideration of server utilization and power consumption.
+
+$$EEI_{MDC} = \frac{ITEU_{sv}}{PUE} \quad (3)$$
+
+The energy efficiency indicator for a micro data centre ( $EEI_{MDC}$ ) can be explained as follows. In the case of a microdata centre operating with multiple servers with low utilization,  $ITEU_{sv}$  will have a low value due to the low CPU utilization, and PUE will show a high value because the power consumption of infrastructure facilities is relatively high compared to the amount of power consumed by IT equipment. Consequently,  $EEI_{MDC}$  will show a low value. On the other hand, in the case of a micro data centre operated with servers with high CPU utilization, the  $ITEU_{sv}$  value will be high, and the PUE will be slightly lower or a similar level to the former case. Therefore,  $EEI_{MDC}$  will have a high value. That is, it can be determined that the higher the value of  $EEI$ , the higher the energy efficiency of the micro data centre.
+
+# 10 Energy efficiency in edge computing
+
+Energy efficiency is a critical issue in edge computing, as the increasing number of connected devices and the amount of data they generate are putting a strain on the power grid. Here are some of the main issues of energy efficiency in edge computing:
+
+- The distributed nature of edge computing. Edge servers are typically located closer to the end users, which means that there are more of them and they are more dispersed. This makes it difficult to manage and optimize their energy consumption.
+- The limited resources of user terminals. User terminals often have limited resources, such as battery power and processing power. This means that they can only handle a certain amount of workload before they start to run out of power.
+- The high volume of data traffic. User terminals need to communicate with edge servers in a micro data centre and with the cloud, which can generate a lot of data traffic. This data traffic can also consume a lot of energy.
+- The need for real-time processing. Some edge applications require real-time processing, which means that the data cannot be sent to the cloud for processing. This can also lead to increased energy consumption.
+
+Considering these points, the following solutions can be applied to improve the energy efficiency of edge computing.
+
+- Data compression can be used to reduce the amount of data that needs to be transmitted and processed. This is especially useful in situations where large amounts of data transfer are required to process and deliver the training data required to build a machine learning training model.
+- Edge servers in a micro data centre should be used to process the data that is generated closest to them. This can help to reduce the amount of data traffic and the energy consumption of edge servers. For example, if a micro data centre is located in a factory, it should be used to process the data that is generated by the machines in that factory.
+- Task offloading can be performed when there are limited resources to process tasks in a user terminal. From an energy efficiency perspective, it is possible to select which servers to offload tasks to, including a cloud computing server based on the cooperative orchestration.
+- Virtualization can be used to consolidate multiple workloads onto a single server. This can help to reduce the number of servers that are needed, which can lead to reduced energy consumption. For example, multiple sensors can be connected to a single server, which can then transmit the data to the cloud.
+
+In addition to these considerations, it is necessary to ensure that the offloading techniques popular in edge computing are efficient from an energy perspective. Offloading can be defined as the process of executing an application from a device with limited computation resources to single or multiple remote devices with more resources. There are two types of offloading: data offloading and computation offloading. Data offloading transfers data from a mobile device with limited storage to
+
+a cloud repository. Computation offloading transfers computation processes of intensive applications to be performed remotely using powerful cloud or edge servers in a micro data centre, overcoming limitations on mobile CPU and battery. The architecture of an offloading system is shown in Figure 2.
+
+![Figure 2 – Offloading architecture diagram. The diagram illustrates the flow of data and tasks between user devices, edge servers, and cloud servers. On the left, 'Devices' (laptop and smartphone) are connected to an 'Edge computing' node. A legend indicates: solid line for 'Data and task', dashed line for 'Result', and gears for 'Processing'. The 'Edge computing' node contains a 'Computing offload' box and a network of small servers. Arrows show data/tasks moving from devices to the edge node, and results returning. From the edge node, data/tasks are offloaded to a 'Cloud computing' node (represented by a cloud with servers) and a 'Data centre' (represented by a rack of servers). Results from both cloud and data centre return to the edge node, and finally to the devices. A label 'L.1307(24)' is in the bottom right corner.](b9ecbc3baefab13719e000faa6e0c7eb_img.jpg)
+
+Figure 2 – Offloading architecture diagram. The diagram illustrates the flow of data and tasks between user devices, edge servers, and cloud servers. On the left, 'Devices' (laptop and smartphone) are connected to an 'Edge computing' node. A legend indicates: solid line for 'Data and task', dashed line for 'Result', and gears for 'Processing'. The 'Edge computing' node contains a 'Computing offload' box and a network of small servers. Arrows show data/tasks moving from devices to the edge node, and results returning. From the edge node, data/tasks are offloaded to a 'Cloud computing' node (represented by a cloud with servers) and a 'Data centre' (represented by a rack of servers). Results from both cloud and data centre return to the edge node, and finally to the devices. A label 'L.1307(24)' is in the bottom right corner.
+
+**Figure 2 – Offloading architecture**
+
+In edge computing, offloading can be done vertically or horizontally. In vertical offloading, an application from a user terminal (i.e., smart mobile device) can be offloaded to nearby edge servers in a micro data centre. Meanwhile, in horizontal offloading, an application from an edge server can be offloaded to other nearby edge servers. Offloading is performed to reduce energy consumption in user terminals, extend user terminals' battery life, and reduce application runtime. Since offloaded tasks are usually executed on edge servers, it is also important to consider energy efficiency in terms of task execution in these servers. To achieve energy-efficient offloading, some aspects need to be considered such as latency, task scheduling, resource allocation and battery life. Table 3 presents several items to consider energy-efficient offloading techniques in edge computing.
+
+**Table 3 – Considerations on energy-efficient offloading in edge computing**
+
+| Category            | Considerations                                                                                                                                                                                                                                                                                                                                                                     |
+|---------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Network latency     | Network latency is crucial in edge computing offloading. It affects the time taken for computation results to return to the user terminal. Reducing latency is key to improving offloading performance. Communication protocol optimization, reduced data transfer sizes, network path selection, caching/pre-fetching, and edge computation offloading can help minimize latency. |
+| Task scheduling     | In edge computing, task scheduling and offloading are techniques that impact energy consumption. Task scheduling optimizes task execution by considering resources and demands, while offloading reduces energy usage on user terminals by transferring tasks to a remote edge server. Coordination of these techniques can lead to improved energy efficiency in edge computing.  |
+| Resource allocation | Resource allocation is also critical in offloading to ensure that computing resources are used efficiently. Offloaded tasks should be assigned to the most appropriate computing resource to minimize energy consumption.                                                                                                                                                          |
+| Battery life        | To extend the battery life of user terminals, offloading should be designed to minimize the energy required for computation tasks of user terminal.                                                                                                                                                                                                                                |
+
+## Appendix I
+
+### Applying renewable energy to micro data centres
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix describes methods and requirements to incorporate renewable energy in micro data centres to improve energy efficiency and minimize the carbon footprint.
+
+### I.1 Recommended renewable energy types
+
+Abundant renewable energy sources are available nowadays, whether they are solar-powered, hydro-powered, wind-powered or geothermal-powered. For hydro, wind and geothermal, the plant to convert these energies into electricity should be constructed in certain places to optimize energy harvesting. It is because hydro, wind and geothermal energy are not available in all areas. Meanwhile, solar energy can be harvested in all areas as long as it receives direct sunlight exposure. Also, solar energy can be constructed in a highly flexible format and capacity. Hence, solar energy is the most viable renewable energy source that can be incorporated into micro data centres.
+
+### I.2 Photovoltaic power plant requirements for micro data centres
+
+To incorporate the photovoltaic (PV) power plant with micro data centres, the PV power plant should have certain requirements and configurations. The requirements and configuration of the PV power plant are as follows:
+
+- Equipped with enough PV panel
+
+The size of the PV panel should be larger than the required power for micro data centres. The energy produced by the PV panel is not steady, but it is highly stochastic. Hence, the average one-day power generation should be larger than the required power for micro data centres.
+
+- Equipped with an energy storage system
+
+An energy storage system must be installed in the PV power plant. The energy storage system stores the generated power from the PV panel during the high generation of solar power. This energy storage system will release the stored energy to supply power for micro data centres during low generation of solar power (during the night or cloudy weather).
+
+- Equipped with solar charge controller
+
+The solar charge controller maintains the charge and discharge mechanisms of the energy storage system. The solar charge controller regulates the power that the PV panel produces, and if the energy storage system is empty, it will charge. Meanwhile, if the energy storage system is full, then the generated power is sent directly to the system by the solar charge controller.
+
+### I.3 Method to incorporate the PV power plant with micro data centres
+
+Incorporating the PV power plant with micro data centres can be done by integrating power from the conventional grid and the PV power plant to supply power for data centres. PVs can be installed on data centre buildings to collect solar power. Since solar power generation depends on the weather and time of day, it is necessary to combine renewable energy sources with conventional power from the grid, as shown in Figure I.1.
+
+An energy management system (EMS) is important to combine renewable energy sources with the power grid. The EMS has the function of optimizing the utilization of power from renewable energy sources and minimizing power usage from the power grid. By implementing that method, the carbon footprint of the micro data centre operation can be minimized. Then, since the energy usage from the power grid is minimized, the energy cost of consuming the power is reduced.
+
+![Diagram showing the integration of renewable energy sources (PV panel) and conventional power (Utility grid) to power a micro data centre. The diagram illustrates AC and DC power flows between components including a Solar charge controller, Inverter, Energy storage system, Circuit breaker, Energy management system, and Micro data centre.](fa859e4e468bfb2710a94527f2c504af_img.jpg)
+
+The diagram illustrates a power system architecture for a micro data centre. On the left, a 'Utility grid' represented by power lines and towers provides AC power (blue line). This line passes through a 'Circuit breaker' and then splits. One path goes to an 'Energy management system' (represented by a monitor icon). The other path goes to an 'Inverter'. A 'PV panel' (solar panel) is connected to a 'Solar charge controller', which is connected to an 'Energy storage system' (represented by two battery icons). The 'Solar charge controller' also connects to the 'Inverter'. The 'Inverter' outputs AC power (blue line) to the 'Energy management system'. The 'Energy management system' is connected to a 'Micro data centre' (represented by three server racks). A legend indicates that blue arrows represent AC power flow and red arrows represent DC power flow. The DC power flow is shown from the PV panel through the Solar charge controller to the Energy storage system, and then from the Energy storage system to the Inverter.
+
+Diagram showing the integration of renewable energy sources (PV panel) and conventional power (Utility grid) to power a micro data centre. The diagram illustrates AC and DC power flows between components including a Solar charge controller, Inverter, Energy storage system, Circuit breaker, Energy management system, and Micro data centre.
+
+L.1307(24)
+
+**Figure I.1 – Integration between renewable energy sources with conventional power from the grid to power a micro data centre.**
+
+Another example of application of renewable energy to a micro data centre can also be found in clause 8.1.4 in [b-ITU-T L.1306].
+
+## Bibliography
+
+- [b-ITU-T L.1306] Recommendation ITU-T L.1306 (2023), *Specification of an edge data centre infrastructure*.
+- [b-ITU-T Y.3073] Recommendation ITU-T Y.3073 (2019), *Framework for service function chaining in information-centric networking*.
+- [b-Beloglazov] A. Beloglazov, J. Abawajy and R. Buyya (2012), *Energy-aware Resource Allocation Heuristics for Efficient Management of Data Centers for Cloud Computing*, *Future Generation Computer Systems*, Vol. 28, No. 5, 755-768.
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |

marked/L/T-REC-L.1318-202208-I_PDF-E/raw.md

@@ -0,0 +1,440 @@
+
+
+**ITU-T**
+
+TELECOMMUNICATION  
+STANDARDIZATION SECTOR  
+OF ITU
+
+**L.1318**
+
+(08/2022)
+
+SERIES L: ENVIRONMENT AND ICTS, CLIMATE  
+CHANGE, E-WASTE, ENERGY EFFICIENCY;  
+CONSTRUCTION, INSTALLATION AND PROTECTION  
+OF CABLES AND OTHER ELEMENTS OF OUTSIDE  
+PLANT
+
+Energy efficiency, smart energy and green data centres
+
+---
+
+**Q factor: A fundamental metric expressing  
+integrated circuit energy efficiency**
+
+Recommendation ITU-T L.1318
+
+# ITU-T L-SERIES RECOMMENDATIONS
+
+## ENVIRONMENT AND ICTS, CLIMATE CHANGE, E-WASTE, ENERGY EFFICIENCY; CONSTRUCTION, INSTALLATION AND PROTECTION OF CABLES AND OTHER ELEMENTS OF OUTSIDE PLANT
+
+|                                                               |                      |
+|---------------------------------------------------------------|----------------------|
+| OPTICAL FIBRE CABLES                                          |                      |
+| Cable structure and characteristics                           | L.100–L.124          |
+| Cable evaluation                                              | L.125–L.149          |
+| Guidance and installation technique                           | L.150–L.199          |
+| OPTICAL INFRASTRUCTURES                                       |                      |
+| Infrastructure including node elements (except cables)        | L.200–L.249          |
+| General aspects and network design                            | L.250–L.299          |
+| MAINTENANCE AND OPERATION                                     |                      |
+| Optical fibre cable maintenance                               | L.300–L.329          |
+| Infrastructure maintenance                                    | L.330–L.349          |
+| Operation support and infrastructure management               | L.350–L.379          |
+| Disaster management                                           | L.380–L.399          |
+| PASSIVE OPTICAL DEVICES                                       | L.400–L.429          |
+| MARINIZED TERRESTRIAL CABLES                                  | L.430–L.449          |
+| E-WASTE AND CIRCULAR ECONOMY                                  | L.1000–L.1199        |
+| POWER FEEDING AND ENERGY STORAGE                              | L.1200–L.1299        |
+| <b>ENERGY EFFICIENCY, SMART ENERGY AND GREEN DATA CENTRES</b> | <b>L.1300–L.1399</b> |
+| ASSESSMENT METHODOLOGIES OF ICTS AND CO2 TRAJECTORIES         | L.1400–L.1499        |
+| ADAPTATION TO CLIMATE CHANGE                                  | L.1500–L.1599        |
+| CIRCULAR AND SUSTAINABLE CITIES AND COMMUNITIES               | L.1600–L.1699        |
+| LOW COST SUSTAINABLE INFRASTRUCTURE                           | L.1700–L.1799        |
+
+For further details, please refer to the list of ITU-T Recommendations.
+
+## Recommendation ITU-T L.1318
+
+## **Q factor: A fundamental metric expressing integrated circuit energy efficiency**
+
+## **Summary**
+
+Recommendation ITU-T L.1318 outlines a method and fundamental metric for expressing integrated circuit energy efficiency, the Q factor. The Q factor could be applied to measure and improve the integrated circuit technology behind information and communication technology itself.
+
+The method consists of two separate parts:
+
+- 1) Method and metric development;
+- 2) Examples of Q factor scores for different integrated circuits and energy and carbon saving potentials in relation to Q factors.
+
+## **History**
+
+| Edition | Recommendation | Approval   | Study Group | Unique ID*                                                                |
+|---------|----------------|------------|-------------|---------------------------------------------------------------------------|
+| 1.0     | ITU-T L.1318   | 2022-08-13 | 5           | <a href="http://handle.itu.int/11.1002/1000/15027">11.1002/1000/15027</a> |
+
+## **Keywords**
+
+Energy efficiency, integrated circuit, metric.
+
+---
+
+\* To access the Recommendation, type the URL <http://handle.itu.int/> in the address field of your web browser, followed by the Recommendation's unique ID. For example, <http://handle.itu.int/11.1002/1000/11830-en>.
+
+## FOREWORD
+
+The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis.
+
+The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics.
+
+The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1.
+
+In some areas of information technology which fall within ITU-T's purview, the necessary standards are prepared on a collaborative basis with ISO and IEC.
+
+### NOTE
+
+In this Recommendation, the expression "Administration" is used for conciseness to indicate both a telecommunication administration and a recognized operating agency.
+
+Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words "shall" or some other obligatory language such as "must" and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party.
+
+## INTELLECTUAL PROPERTY RIGHTS
+
+ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process.
+
+As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents/software copyrights, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the appropriate ITU-T databases available via the ITU-T website at <http://www.itu.int/ITU-T/ipr/>.
+
+© ITU 2022
+
+All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU.
+
+## Table of Contents
+
+|                                                                                                                        | Page |
+|------------------------------------------------------------------------------------------------------------------------|------|
+| 1 Scope .....                                                                                                          | 1    |
+| 2 References.....                                                                                                      | 1    |
+| 3 Definitions .....                                                                                                    | 1    |
+| 3.1 Terms defined elsewhere .....                                                                                      | 1    |
+| 3.2 Terms defined in this Recommendation.....                                                                          | 1    |
+| 4 Abbreviations and acronyms .....                                                                                     | 1    |
+| 5 Conventions .....                                                                                                    | 2    |
+| 6 The framework or methodology — method and metric development .....                                                   | 2    |
+| 6.1 The framework or methodology for Q factor .....                                                                    | 2    |
+| 6.2 The Q factor metric with examples of Q factor scores.....                                                          | 3    |
+| Appendix I – Challenges, feasible technologies and recent and ongoing work .....                                       | 4    |
+| Appendix II – Carbon saving potential: energy and carbon saving potential relation to Q factor .....                   | 5    |
+| Appendix III – Example of governmental programme mandating energy efficient computers.....                             | 7    |
+| Appendix IV – Performance metrics for different semiconductor technologies and the corresponding electricity use ..... | 8    |
+| Bibliography.....                                                                                                      | 10   |
+
+## Introduction
+
+As [b-Lewis] describes, current computing technology is not sustainable, owing to the increased heat generation that accompanies the ever increasing capability of chips. The large number of such chips packed into a limited space makes cooling a major challenge, which will eventually become insurmountable. Therefore, it is likely that the trend of improved performance provided by increased power consumption is reaching its end, unless the relationship between performance and heat generation can be broken by new technological solutions. Energy-efficient computing, and reversible adiabatic<sup>1</sup> computing specifically, could be one of these solutions, as it would fulfil the need described by [b-Lewis] to reduce power consumption per unit of computation, potentially within the next ten years.
+
+[b-Andrae] provides a comparison of the energy efficiency of reversible versus conventional computing: "If a traditional 180 W processor chip using 5 nm node ... would process the anticipated operations in 2030 with current transistor technology, an absurd amount of electricity will be used for computing. The same chip using reversible computing would use only 0.08 W." Appendix IV presents tables of performance metrics for different semiconductor technologies and the corresponding electricity use.
+
+There are several ways in which the energy efficiency of integrated circuits (ICs) can be expressed. [b-Kenneth] proposed a Q factor based on radian frequency, electrical and magnetic energies stored in the IC, and the power dissipation from the IC. [b-Ionescu] proposed the E factor, an energy factor related to the state change in the field-effect transistors, dependent on physics, materials and voltages.
+
+The focus of this Recommendation is the Q factor as a metric by which the energy efficiency of IC technologies can be measured. The Q factor described herein thus provides a way of establishing the energy efficiency of ICs, computing and information and communication technology (ICT).
+
+---
+
+<sup>1</sup> Adiabatic: Greek term for a "closed system", in contrast to the term diabatic for an "open system".
+
+## Recommendation ITU-T L.1318
+
+## **Q factor: A fundamental metric expressing integrated circuit energy efficiency**
+
+## **1 Scope**
+
+This Recommendation defines the integrated circuit metric for energy efficiency (TIME) as the Q factor (also known as "quality factor" or "Q"). Q factor provides a key means to accurately express energy efficiency at the integrated circuit (IC) level.
+
+This Recommendation defines Q factor as a metric for IC energy efficiency;
+
+This Recommendation is applicable to all ICs and differentiates ICs with  $Q \geq 1000$  (highly energy efficient) from those ICs with  $Q = 1$  (current ICs).
+
+## **2 References**
+
+The following ITU-T Recommendations and other references contain provisions which, through reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation.
+
+None.
+
+## **3 Definitions**
+
+### **3.1 Terms defined elsewhere**
+
+None.
+
+### **3.2 Terms defined in this Recommendation**
+
+This Recommendation defines the following terms:
+
+**3.2.1 dynamic energy used per cycle:** The average energy consumed for one switching transition of a device.
+
+**3.2.2 energy dissipated per cycle:** The energy required to erase one bit of information.
+
+**3.2.3 irreversible:** A process that is not reversible, thermodynamically limited.
+
+**3.2.4 quality factor (Q factor):** Ratio of dynamic energy used per cycle to energy dissipated per cycle.
+
+**3.2.5 reversible:** Not thermodynamically limited, capable of circumventing thermodynamic limits.
+
+## **4 Abbreviations and acronyms**
+
+This Recommendation uses the following abbreviations and acronyms:
+
+**BARC** Ballistic Asynchronous Reversible Computing
+
+**BARCS** Ballistic Asynchronous Reversible Computing in Superconductors
+
+**CMOS** Complementary Metal Oxide Semiconductor
+
+|         |                                                              |
+|---------|--------------------------------------------------------------|
+| IC      | Integrated Circuit                                           |
+| ICT     | Information and Communication Technology                     |
+| PUE     | Power Usage Effectiveness                                    |
+| Q2LAL   | Quiet Two-Level Adiabatic Logic                              |
+| R-QCA   | Reversible Quantum-dot Cellular Automaton                    |
+| RA-CMOS | Reversible Adiabatic Complementary Metal Oxide Semiconductor |
+| RNRL    | Reversible Nanomechanical Rod Logics                         |
+| RQFP    | Reversible Quantum Flux Parametron                           |
+| S2LAL   | Static Two-Level Adiabatic Logic                             |
+| TIME    | The Integrated circuit Metric for Energy efficiency          |
+
+## 5 Conventions
+
+None.
+
+## 6 The framework or methodology – method and metric development
+
+### 6.1 The framework or methodology for Q factor
+
+The framework or methodology for the Q factor metric – defined by Equations (1) to (3) – is the physics of information, that is, physical information and the physical foundations of computation.
+
+Q factor ( $Q$ ) – as expressed in this Recommendation – is a new metric to express the energy efficiency of ICs.
+
+$Q$  is a dimensionless parameter expressed as the ratio of dynamic energy used per cycle ( $E_{\text{dyn}}$ ) to energy dissipated per cycle ( $E_{\text{diss-heat}}$ ). Q factor ( $Q$ ) is a metric based on Landauer's principle for the measurement of energy efficiency for ICs, namely  $E_{\text{diss-heat}} = kT \ln 2$ .
+
+Equations (1) to (3) describe how  $Q$  is derived:
+
+$$Q = E_{\text{dyn}}/E_{\text{diss-heat}} \quad (1)$$
+
+$$E_{\text{dyn}} = (C_L \times V^2) + 1/(\alpha \times f_c) \times I_{\text{off}} \times V \quad (2)$$
+
+$$E_{\text{diss-heat}} = k_b \times T \times \ln 2 \quad (3)$$
+
+where:
+
+|                        |                                                              |
+|------------------------|--------------------------------------------------------------|
+| $Q$                    | is the quality factor                                        |
+| $E_{\text{dyn}}$       | is the dynamic energy used per cycle                         |
+| $E_{\text{diss-heat}}$ | is the energy dissipated per cycle                           |
+| $\alpha$               | is the switching probability                                 |
+| $f_c$                  | is the clock frequency                                       |
+| $I_{\text{off}}$       | is the leakage current from each switch in the off-state     |
+| $C_L$                  | is the load capacitance                                      |
+| $V$                    | is the voltage across the gate                               |
+| $k_b$                  | is the Boltzmann constant [J/K], and                         |
+| $T$                    | is the temperature at which the transistor is operating [K]. |
+
+Appendix I describes challenges in the development of more energy efficient IC technology, lists feasible such technologies and presents recent and ongoing work that can lead to their development.
+
+### 6.2 The Q factor metric with examples of Q factor scores
+
+Table 1 shows Q factor scores for the reversible computing technologies listed in Appendix I, and which promise levels of energy efficiency significantly greater than that of current computing.
+
+**Table 1 – Expected Q factor performance scores for "information is physical" reversible computing technologies**
+
+| Technology                                                                        | <i>Q</i>                     | Features                             | Readiness level |
+|-----------------------------------------------------------------------------------|------------------------------|--------------------------------------|-----------------|
+| 1. Reversible adiabatic CMOS (RA-CMOS)                                            | $\geq 1000$ [b-Frank-2]      | Room temperature, 300 Kelvin, CMOS   | Near-term       |
+| 2. Reversible quantum flux parametron (RQFP)                                      | Ultra-high-Q                 | Superconducting resonators           | Mid-term        |
+| 3. Reversible quantum-dot cellular automaton (R-QCA)                              | 10 000 to 100 000 [b-Torres] | Cryogenic (4 Kelvin), superconductor | Long-term       |
+| 4. Reversible nanomechanical rod logics (RNRL)                                    |                              |                                      | Very long-term  |
+| 5. Ballistic asynchronous reversible computing in superconductors (BARC or BARCS) |                              |                                      | Very long-term  |
+| NOTE – In current computing, <i>Q</i> = 1.                                        |                              |                                      |                 |
+
+As stated in clause 6.1, the methodology for the Q metric [b-Frank-2] involves the fundamentals of the physics of information [b-Anderson]. RA-CMOS technology, specifically S2LAL combined with the High-Q resonator [b-Frank-3], in page 29 provides a potential near-term solution.
+
+*Q* = 1 refers to end-of-nodes in [b-ITRS].
+
+Appendix II shows potential carbon saving from different achievements of values of *Q*.
+
+Appendix III shows an example of how energy efficient computers can be mandated by governments.
+
+## Appendix I
+
+### Challenges, feasible technologies and recent and ongoing work
+
+(This appendix does not form an integral part of this Recommendation.)
+
+The challenge in developing energy efficient computing technology lies in educating the ICT sector of the need for "fundamental understanding of computation as a distinct physical process with information as its physical currency" as stated by [b-Anderson] in a special issue of the Entropy journal [b-Entropy], dedicated to clarifying and advancing "the physical understanding of information and computation." Gaining such an understanding in a timely manner will enable the ICT sector to navigate the technology inflection point from diabatic to adiabatic computing and meet the ICT sector 1.5°C by 2025 trajectory.
+
+Feasible technologies for developing energy efficient computing are described in the Entropy journal cover article "Quantum Foundations of Classical Reversible Computing" [b-Frank-2]. The five existing and proposed reversible computing technologies are based on the methodology of the physics of information and are far more energy efficient than the current diabatic irreversible computing technology:
+
+- 1 RA-CMOS
+- 2 RQFP
+- 3 R-QCA
+- 4 RNRL
+- 5 BARC or BARCS.
+
+(See clause 6.2 for Q factor values for some of the above technologies.)
+
+The near-term implementation impact path will likely involve the first computing technology in the above list – RA-CMOS: "this class of implementation technologies for reversible computing refers to a logic design discipline based on ordinary CMOS (complementary metal-oxide-semiconductor) field-effect transistors..." [b-Frank-2], p. 36. The implementation of technologies 2, 3, 4 and 5 is – due to their readiness – realistic in either mid-term or long-term.
+
+Recent and ongoing work within the RA-CMOS technology are: S2LAL, which "should be capable of demonstrating a greater level of energy efficiency than *any* other semiconductor-based digital logic family known today" [b-Frank-1]; Q2LAL, with improvements to S2LAL [b-DeBenedictis]; and a patent-pending high-Q resonant oscillator to provide power supplies suitable for driving adiabatic circuits [b-Frank-3] is reported in page 29, with an efficiency goal of  $Q \geq 1000$ .
+
+## Appendix II
+
+### Carbon saving potential: energy and carbon saving potential relation to $Q$ factor
+
+(This appendix does not form an integral part of this Recommendation.)
+
+[b-ITU-T L.1470] describes the carbon footprint of the ICT sector as largely dependent on the use of electricity and its carbon intensity, and that ICT is electrified but not decarbonized. Decarbonizing the electricity supply with power from renewable sources will help to lower greenhouse gas emissions. However, the energy efficiency of the computing technology behind ICT must itself be addressed. Making that technology so energy efficient that ICT usage requires less electricity to begin with will contribute to decarbonizing ICT, thus reducing the sector's global greenhouse gas emissions. An additional benefit could be better durability of equipment.
+
+Current IC technology has  $Q = 1$  – virtually all the energy going in goes out – as waste heat. "As of 2011, computers have a computing efficiency of about 0.00001%" [b-Lewis]. This  $Q = 1$  energy inefficiency has a high cost, requiring as much electricity to cool the ICT as to run it, as illustrated in Table II.1, which shows the allocation of data centre electricity usage for data centres in the USA in 2014 [b-Energy]. Hence the power usage effectiveness (PUE) in 2014 was, on average, 2.32. Current data centres focusing on efficiency typically achieve PUE values of 1.2 or less [b-NREL].
+
+**Table II.1 – Allocation of data centre electricity usage in the USA in 2014**
+
+| Data centre electricity end use     | Approx. % |
+|-------------------------------------|-----------|
+| Servers                             | 43        |
+| Cooling and power provision systems | 43        |
+| Storage drives                      | 11        |
+| Network                             | 3         |
+
+Note that in Table II.1 the percentages allocated to servers and to cooling and power provision are equal – 43%. Today's computers, which run on technology with  $Q = 1$ , dissipate virtually all the energy input as waste heat; therefore, it is not surprising that it takes as much electricity to cool today's computers as it does to run them.
+
+Because  $Q \geq 1000$  computers would operate so efficiently and produce so little heat, costs related to both the cooling systems and processing should become minimal, again significantly reducing the amount of electricity needed and corresponding emissions. In addition, the impact on precious resources directly or indirectly used for current cooling needs – such as water [b-Mytton] – would be greatly lessened.
+
+Looking at the data centre subsector, Table II.2 compares the potential difference in electricity consumption between current  $Q = 1$  IC technology and  $Q = 1000$  IC technology.
+
+**Table II.2 – Comparison of data centre electricity consumption with  $Q = 1$  vs  $Q = 1000$  IC technology [b-ITU-T L.1470], Table A-1**
+
+| $Q$  | Electricity (TWh) |        |        |        |
+|------|-------------------|--------|--------|--------|
+|      | 2015              | 2020   | 2025   | 2030   |
+| 1    | ≈205              | ≈215   | ≈235   | ≈257   |
+| 1000 | ≈0.205            | ≈0.230 | ≈0.235 | ≈0.277 |
+
+For data centre servers using  $Q = 1000$  computing technology ICs, the electricity consumption would be *significantly* reduced, by at least a factor of 1000.
+
+Similarly, Table II.3 compares the use state power values for combined data centres and enterprise networks and illustrates that electricity requirements would be far lower when  $Q = 1000$ .
+
+**Table II.3 – Comparison of electricity consumption for data centres and enterprise networks with  $Q = 1$  vs  $Q = 1000$  IC technology [b-ITU-T L.1470], Tables V.3, V.4**
+
+| $Q$  | Electricity (TWh) |        |
+|------|-------------------|--------|
+|      | 2015              | 2030   |
+| 1    | ≈220              | ≈411   |
+| 1000 | ≈0.220            | ≈0.411 |
+
+The carbon saving potential comes from developing ICT with a high  $Q$  value to replace current  $Q = 1$  ICT. Vastly lowered power requirements in data centres – resulting from using ICT that in turn uses ICs with high  $Q$  value – will make it feasible to install onsite renewable energy sources, especially, for example, solar photovoltaic systems with battery backup, eliminating emissions caused by transmission and distribution losses [b-Surana], [b-US].
+
+## Appendix III
+
+### **Example of governmental programme mandating energy efficient computers**
+
+(This appendix does not form an integral part of this Recommendation.)
+
+As of 2021, computers sold in the state of California (United States of America) must meet energy consumption standards. According to a 2016 report [b-California-1] by the state's Energy Commission, computers and computer monitors in the state account for up to 2.9 percent of residential electricity use and 7 percent of commercial electricity use, primarily in offices and schools. In order to reduce the state's carbon footprint, California adopted appliance energy consumption standards for computers and computer monitors, and the standards came fully into effect in 2021 [b-California-2]. Manufacturers must certify with the California Energy Commission that their products meet the standards [b-California-3]. This information is available to the public.
+
+## Appendix IV
+
+### Performance metrics for different semiconductor technologies and the corresponding electricity use
+
+(This appendix does not form an integral part of this Recommendation.)
+
+This appendix describes current (2020) and future estimates (2030) for different semiconductor technologies and the corresponding electricity use. Tables IV.1 and IV.2 use approaches from section III.D in [b-Andrae].
+
+Table IV.1 provides estimates of the amounts of electricity used for computation in 2020 under certain assumptions.
+
+**Table IV.1 – Performance metrics for different semiconductor technologies and the corresponding electricity use in 2020**
+
+| Metric                                    | Typical CMOS today, <sup>1</sup> | Typical CMOS today, <sup>2</sup> |                            |
+|-------------------------------------------|----------------------------------|----------------------------------|----------------------------|
+| Node                                      | 7 nm                             | 14 nm                            |                            |
+| Power, W                                  | 300                              | 100                              |                            |
+| GFLOP/s                                   | 20 700                           | 9000                             | FLOP $\approx$ computation |
+| GFLOP/s/W                                 | 69                               | 90                               |                            |
+| pJ/computation                            | 14.5                             | 11.1                             |                            |
+| Computations/s global in 2020             | $\approx 1.57 \times 10^{22}$    |                                  |                            |
+| TWh globally per year for all computation | 1993                             | 1528                             |                            |
+| MW to run a 1 EFLOP/s machine             | 14.5                             | 11.1                             |                            |
+
+Table IV.2 provides estimates of the amounts of electricity to be used in 2030 under certain assumptions of future performance.
+
+**Table IV.2 – Performance metrics for different semiconductor technologies and the corresponding electricity use in 2030**
+
+| Metric                                    | Typical CMOS today,1          | Typical CMOS today,2 | CMOS theoretical prediction 2030,1 | CMOS theoretical prediction 2030,2 | Reversible logic |                            |
+|-------------------------------------------|-------------------------------|----------------------|------------------------------------|------------------------------------|------------------|----------------------------|
+| Node                                      | 7 nm                          | 14 nm                |                                    |                                    |                  |                            |
+| Power, W                                  | 300                           | 100                  |                                    | 180                                | 0.08             |                            |
+| GFLOP/s                                   | 20 700                        | 9000                 |                                    | 5 7600                             | 57 600           | FLOP $\approx$ computation |
+| GFLOP/s/W                                 | 69                            | 90                   | 5498                               | 320                                | 720 000          |                            |
+| pJ/computation                            | 14.5                          | 11.1                 | 0.182                              | 3.12                               | 0.0014           |                            |
+| Computations/s globally in 2030           | $\approx 3.08 \times 10^{24}$ |                      |                                    |                                    |                  |                            |
+| TWh globally per year for all computation | $\approx 390\ 000$            | $\approx 300\ 000$   | $\approx 4900$                     | $\approx 84\ 000$                  | $\approx 37$     |                            |
+| MW to run a 1 EFLOP/s machine             | 14.5                          | 11.1                 | 0.182                              | 3.12                               | 0.0014           |                            |
+
+With the achievement of  $\approx 3$  yottacomputations/s in 2030, the J/computation should improve 41% per year from 2020 to 2030, reaching 0.074 pJ/computation (13 500 GFLOP/s/W), to keep computing electricity flat.
+
+## Bibliography
+
+- [b-ITU-T L.1470] Recommendation ITU-T L.1470 (2020), *Greenhouse gas emissions trajectories for the information and communication technology sector compatible with the UNFCCC Paris Agreement*.
+- [b-Anderson] Anderson, N.G. (2021), *Entropy Special Issue*, Entropy, Vol. 23, No. 6.
+- [b-Andrae] Andrae, A.S.G. (2019), *Prediction Studies of Electricity Use of Global Computing in 2030*. Int. J. Sci. Eng. Invest. Vol. 8, No. 86, pp. 27–33.
+- [b-California-1] California Energy Commission. (2016). *2016 Appliance Efficiency Rulemaking, Staff Report: Final Analysis of Computers, Computer Monitors, and Signage Displays*. <https://efiling.energy.ca.gov/GetDocument.aspx?tn=213548&DocumentContentId=23311>
+- [b-California-2] California Energy Commission. (2021). *CEC Compliance Advisory: Appliance Efficiency Regulations For Computers And Computer Monitors*. <https://www.energy.ca.gov/sites/default/files/2021-04/Computers%20Reg%20Adv%20final.pdf>
+- [b-California-3] California Energy Commission. (2022). *Appliance Regulations Certification Assistance*. <https://www.energy.ca.gov/rules-and-regulations/appliance-efficiency-regulations-title-20/appliance-regulations-certification>
+- [b-DeBenedictis] DeBenedictis, E.P. (2021), *Energy Management for Adiabatic Circuits*. <https://ar.zettaflops.org/CATC/EMgt4Adia-ZF008-v1.2.pdf>
+- [b-Energy] Energy Innovation Policy & Technology (2020), *How Much Energy Do Data Centers Really Use?* <https://energyinnovation.org/2020/03/17/how-much-energy-do-data-centers-really-use/>
+- [b-Entropy] Entropy (2021), Vol. 23, No. 6 (June).
+- [b-Frank-1] Frank, M.P., Brocato, R.W., Tierney, B.D., Missert, N., Hsia, A.H. (2020). *Reversible Computing with Fast, Fully Static, Fully Adiabatic CMOS*. 2020 Int'l Conf. on Rebooting Computing (ICRC), Atlanta, Georgia, USA, Dec. 1–3.
+- [b-Frank-2] Frank, M.P., Shukla, K. (2021), *Quantum Foundations of Classical Reversible Computing*, Entropy, Vol. 23, No. 6, pp. 701.
+- [b-Frank-3] Frank, M.P. (2021). *Current Status of Reversible Computing*. <https://www.osti.gov/biblio/1869234>
+- [b-Ionescu] Ionescu, A.M. (2017), *Energy efficient computing and sensing in the Zettabyte era: From silicon to the cloud*. 2017 IEEE International Electron Devices Meeting (IEDM) pp. 1–2).
+- [b-ITRS] International Technology Roadmap for Semiconductors (2013). <http://www.itrs2.net/2013-itrs.html>
+- [b-Kenneth] Kenneth, O. (1998), *Estimation methods for quality factors of inductors fabricated in silicon integrated circuit process technologies*. IEEE Journal of Solid-state circuits, Vol. 33, No. 8, pp. 1249-1252.
+- [b-Lewis] Lewis, T.G., Scott, A. (2021), *Sustainable Computing*. February, 10 pp. <https://dl.acm.org/doi/pdf/10.1145/3450612>
+- [b-Mytton] Mytton, D. (2021), *Data Centre Water Consumption*. npj Clean Water, Vol. 4, No. 11.
+- [b-NREL] National Renewable Energy Laboratory, High-Performance Computing Data Center Power Usage Effectiveness, 2020. <https://www.nrel.gov/computational-science/measuring-efficiency-pue.html>
+
+- [b-Surana] Surana, K., & Jordaan, S. M. (2019). *The climate mitigation opportunity behind global power transmission and distribution*. *Nature Climate Change*, 9(9), 660-665.
+- [b-Torres] Torres, F.S. (2021, June 20). Private email re Torres, F. S., Niemann, P., Wille, R., & Drechsler, R. (2019). *Near zero-energy computation using quantum-dot cellular automata*. *ACM Journal on Emerging Technologies in Computing Systems (JETC)*, 16(1), 1-16
+- [b-US] U.S. Energy Information Administration (2021), *How Much Electricity is Lost in Electricity Transmission and Distribution in the United States?* 4 November 2021. <https://www.eia.gov/tools/faqs/faq.php?id=105&t=3>
+
+
+
+
+
+## SERIES OF ITU-T RECOMMENDATIONS
+
+|                 |                                                                                                                                                                  |
+|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| Series A        | Organization of the work of ITU-T                                                                                                                                |
+| Series D        | Tariff and accounting principles and international telecommunication/ICT economic and policy issues                                                              |
+| Series E        | Overall network operation, telephone service, service operation and human factors                                                                                |
+| Series F        | Non-telephone telecommunication services                                                                                                                         |
+| Series G        | Transmission systems and media, digital systems and networks                                                                                                     |
+| Series H        | Audiovisual and multimedia systems                                                                                                                               |
+| Series I        | Integrated services digital network                                                                                                                              |
+| Series J        | Cable networks and transmission of television, sound programme and other multimedia signals                                                                      |
+| Series K        | Protection against interference                                                                                                                                  |
+| <b>Series L</b> | <b>Environment and ICTs, climate change, e-waste, energy efficiency; construction, installation and protection of cables and other elements of outside plant</b> |
+| Series M        | Telecommunication management, including TMN and network maintenance                                                                                              |
+| Series N        | Maintenance: international sound programme and television transmission circuits                                                                                  |
+| Series O        | Specifications of measuring equipment                                                                                                                            |
+| Series P        | Telephone transmission quality, telephone installations, local line networks                                                                                     |
+| Series Q        | Switching and signalling, and associated measurements and tests                                                                                                  |
+| Series R        | Telegraph transmission                                                                                                                                           |
+| Series S        | Telegraph services terminal equipment                                                                                                                            |
+| Series T        | Terminals for telematic services                                                                                                                                 |
+| Series U        | Telegraph switching                                                                                                                                              |
+| Series V        | Data communication over the telephone network                                                                                                                    |
+| Series X        | Data networks, open system communications and security                                                                                                           |
+| Series Y        | Global information infrastructure, Internet protocol aspects, next-generation networks, Internet of Things and smart cities                                      |
+| Series Z        | Languages and general software aspects for telecommunication systems                                                                                             |