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Chapter 4 Equipment for General Use | 480.7(G)(1) | Plaques or directories shall be installed in accordance with 705.10. Exception: This requirement does not apply where a disconnect in 480.7(A) is not required. [480.7(G)(1)](https://2023.antflix.net#480.7(G)(1)) | https://2023.antflix.net#480.7(G)(1) |
Chapter 4 Equipment for General Use | 480.7(G)(2) | A permanent plaque or directory shall be installed in accordance with 710.10. [480.7(G)(2)](https://2023.antflix.net#480.7(G)(2)) | https://2023.antflix.net#480.7(G)(2) |
Chapter 4 Equipment for General Use | 480.8 | Batteries constructed of an electrically conductive container shall have insulating support if a voltage is present between the container and ground. [480.8](https://2023.antflix.net#480.8) | https://2023.antflix.net#480.8 |
Chapter 4 Equipment for General Use | 480.9 | For battery chemistries with corrosive electrolyte, the structure that supports the battery shall be resistant to deteriorating action by the electrolyte. Metallic structures shall be provided with nonconducting support members for the cells, or shall be constructed with a continuous insulating material. Paint alone shall not be considered as an insulating material. [480.9](https://2023.antflix.net#480.9) | https://2023.antflix.net#480.9 |
Chapter 4 Equipment for General Use | 480.10 | Battery locations shall conform to 480.10(A) through (G). [480.10](https://2023.antflix.net#480.10) | https://2023.antflix.net#480.10 |
Chapter 4 Equipment for General Use | 480.10(A) | Provisions appropriate to the battery technology shall be made for sufficient diffusion and ventilation of gases from the battery, if present, to prevent the accumulation of an explosive mixture. Informational Note No. 1: See NFPA 1-2021, Fire Code, Chapter 52, for ventilation considerations for specific battery chemistries. Informational Note No. 2: Some battery technologies do not require ventilation. Informational Note No. 3: See IEEE Std 1635-2012/ASHRAE Guideline 21-2012, Guide for the Ventilation and Thermal Management of Batteries for Stationary Applications, for additional information on the ventilation of stationary battery systems. [480.10(A)](https://2023.antflix.net#480.10(A)) | https://2023.antflix.net#480.10(A) |
Chapter 4 Equipment for General Use | 480.10(B) | Guarding of live parts shall comply with 110.27. [480.10(B)](https://2023.antflix.net#480.10(B)) | https://2023.antflix.net#480.10(B) |
Chapter 4 Equipment for General Use | 480.10(C) | Spaces about stationary standby batteries shall comply with 110.26 and 110.34. Working space shall be measured from the edge of the battery cabinet, racks, or trays. For battery racks, there shall be a minimum clearance of 25 mm (1 in.) between a cell container and any wall or structure on the side not requiring access for maintenance. Battery stands shall be permitted to contact adjacent walls or structures, provided that the battery shelf has a free air space for not less than 90 percent of its length. Informational Note: Additional space is often needed to accommodate battery hoisting equipment, tray removal, or spill containment. [480.10(C)](https://2023.antflix.net#480.10(C)) | https://2023.antflix.net#480.10(C) |
Chapter 4 Equipment for General Use | 480.10(D) | Where top terminal batteries are installed on tiered racks or on shelves of battery cabinets, working space in accordance with the battery manufacturer's instructions shall be provided between the highest point on a cell and the row, shelf, or ceiling above that point. Informational Note: See IEEE 1187-2013, IEEE Recommended Practice for Installation Design and Installation of Valve-Regulated Lead-Acid Batteries for Stationary Applications, for guidance for top clearance of valve-regulated lead-acid batteries, which are commonly used in battery cabinets. [480.10(D)](https://2023.antflix.net#480.10(D)) | https://2023.antflix.net#480.10(D) |
Chapter 4 Equipment for General Use | 480.10(E) | Personnel doors intended for entrance to, and egress from, rooms designated as battery rooms shall open at least 90 degrees in the direction of egress and shall be equipped with listed panic or listed fire exit hardware. [480.10(E)](https://2023.antflix.net#480.10(E)) | https://2023.antflix.net#480.10(E) |
Chapter 4 Equipment for General Use | 480.10(F) | Gas piping shall not be permitted in dedicated battery rooms. [480.10(F)](https://2023.antflix.net#480.10(F)) | https://2023.antflix.net#480.10(F) |
Chapter 4 Equipment for General Use | 480.10(G) | Illumination shall be provided for working spaces containing stationary standby batteries. The lighting outlets shall not be controlled by automatic means only. Additional lighting outlets shall not be required where the work space is illuminated by an adjacent light source. The location of luminaires shall not result in the following: Expose personnel to energized battery components while performing maintenance on the luminaires in the battery spaceCreate a hazard to the battery upon failure of the luminaire [480.10(G)](https://2023.antflix.net#480.10(G)) | https://2023.antflix.net#480.10(G) |
Chapter 4 Equipment for General Use | 480.11(A) | Each vented cell shall be equipped with a flame arrester. Informational Note: A flame arrester prevents destruction of the cell due to ignition of gases within the cell by an external spark or flame. [480.11(A)](https://2023.antflix.net#480.11(A)) | https://2023.antflix.net#480.11(A) |
Chapter 4 Equipment for General Use | 480.11(B) | Where the battery is constructed such that an excessive accumulation of pressure could occur within the cell during operation, a pressure-release vent shall be provided. [480.11(B)](https://2023.antflix.net#480.11(B)) | https://2023.antflix.net#480.11(B) |
Chapter 4 Equipment for General Use | 480.12 | Flexible cables, as identified in Table 400.4, in sizes 2/0 AWG and larger shall be permitted within the battery enclosure from battery terminals to a nearby junction box where they shall be connected to an approved wiring method. Flexible battery cables shall also be permitted between batteries and cells within the battery enclosure. Such cables shall be listed and identified for the environmental conditions. Flexible, fine-stranded cables shall only be used with terminals, lugs, devices, or connectors in accordance with 110.14. [480.12](https://2023.antflix.net#480.12) | https://2023.antflix.net#480.12 |
Chapter 4 Equipment for General Use | 480.13 | Battery circuits exceeding 100 volts between the conductors or to ground shall be permitted to operate with ungrounded conductors, provided a ground-fault detector and indicator is installed to monitor for ground faults. [480.13](https://2023.antflix.net#480.13) | https://2023.antflix.net#480.13 |
Chapter 4 Equipment for General Use | 495.1 | This article covers the general requirements for equipment operating at more than 1000 volts ac, 1500 volts dc, nominal. Informational Note No. 1: See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for electrical safety requirements for employee workplaces. Informational Note No. 2: See ANSI Z535.4-2011, Product Signs and Safety Labels, for further information on hazard signs and labels. Informational Note No. 3: See IEEE 3001.5-2013, Recommended Practice for the Application of Power Distribution Apparatus in Industrial and Commercial Power Systems, for information regarding power distribution apparatus. [495.1](https://2023.antflix.net#495.1) | https://2023.antflix.net#495.1 |
Chapter 4 Equipment for General Use | 495.2 | Except as modified within this article, reconditioned equipment shall not be permitted. [495.2](https://2023.antflix.net#495.2) | https://2023.antflix.net#495.2 |
Chapter 4 Equipment for General Use | 495.3(A) | Installation of electrical equipment containing more than 38 L (10 gal) of flammable oil per unit shall meet the requirements of Parts II and III of Article 450. [495.3(A)](https://2023.antflix.net#495.3(A)) | https://2023.antflix.net#495.3(A) |
Chapter 4 Equipment for General Use | 495.3(B) | Enclosures in damp or wet locations shall meet the requirements of 312.2. [495.3(B)](https://2023.antflix.net#495.3(B)) | https://2023.antflix.net#495.3(B) |
Chapter 4 Equipment for General Use | 495.22 | Means shall be provided to completely isolate an item of equipment from all ungrounded conductors. The use of isolating switches shall not be required where there are other ways of de-energizing the equipment for inspection and repairs, such as draw-out-type switchgear units and removable truck panels. Isolating switches not interlocked with an approved circuit-interrupting device shall be provided with a sign warning against opening them under load. The warning sign(s) or label(s) shall comply with 110.21(B). An identified fuseholder and fuse shall be permitted as an isolating switch. [495.22](https://2023.antflix.net#495.22) | https://2023.antflix.net#495.22 |
Chapter 4 Equipment for General Use | 495.23 | Proper switching sequence for regulators shall be ensured by use of one of the following: Mechanically sequenced regulator bypass switch(es)Mechanical interlocksSwitching procedure prominently displayed at the switching location [495.23](https://2023.antflix.net#495.23) | https://2023.antflix.net#495.23 |
Chapter 4 Equipment for General Use | 495.24 | In field-fabricated installations, the minimum air separation between bare live conductors and between such conductors and adjacent grounded surfaces shall not be less than the values given in Table 495.24. These values shall not apply to interior portions or exterior terminals of equipment designed, manufactured, and tested in accordance with accepted national standards. Table 495.24 Minimum Clearance of Live Parts Nominal Voltage Rating (kV) Impulse Withstand, Basic Impulse Level (BIL) (kV) Minimum Clearance of Live Parts Phase-to-Phase Phase-to-Ground Indoors Outdoors Indoors Outdoors Indoors Outdoors mm in. mm in. mm in. mm in. 2.4—4.16 60 95 115 4.5 180 7 80 3.0 155 6 7.2 75 95 140 5.5 180 7 105 4.0 155 6 13.8 95 110 195 7.5 305 12 130 5.0 180 7 14.4 110 110 230 9.0 305 12 170 6.5 180 7 23 125 150 270 10.5 385 15 190 7.5 255 10 34.5 150 150 320 12.5 385 15 245 9.5 255 10 200 200 460 18.0 460 18 335 13.0 335 13 46 - 200 - - 460 18 - - 335 13 - 250 - - 535 21 - - 435 17 69 - 250 - - 535 21 - - 435 17 - 350 - - 790 31 - - 635 25 115 - 550 - - 1350 53 - - 1070 42 138 - 550 - - 1350 53 - - 1070 42 - 650 - - 1605 63 - - 1270 50 161 - 650 - - 1605 63 - - 1270 50 - 750 - - 1830 72 - - 1475 58 230 - 750 - - 1830 72 - - 1475 58 - 900 - - 2265 89 - - 1805 71 - 1050 - - 2670 105 - - 2110 83 Note: The values given are the minimum clearance for rigid parts and bare conductors under favorable service conditions. They shall be increased for conductor movement or under unfavorable service conditions or wherever space limitations permit. The selection of the associated impulse withstand voltage for a particular system voltage is determined by the characteristics of the overvoltage (surge) protective equipment. [495.24](https://2023.antflix.net#495.24) | https://2023.antflix.net#495.24 |
Chapter 4 Equipment for General Use | 495.25 | Installations where the possibility of back-feed exists shall comply with 495.25(A) and (B). [495.25](https://2023.antflix.net#495.25) | https://2023.antflix.net#495.25 |
Chapter 4 Equipment for General Use | 495.25(A) | A permanent sign in accordance with 110.21(B) shall be installed on the disconnecting means enclosure or immediately adjacent to open disconnecting means with the following words or equivalent: DANGER - CONTACTS ON EITHER SIDE OF THIS DEVICE MAY BE ENERGIZED BY BACKFEED. [495.25(A)](https://2023.antflix.net#495.25(A)) | https://2023.antflix.net#495.25(A) |
Chapter 4 Equipment for General Use | 495.25(B) | A permanent and legible single-line diagram of the local switching arrangement, clearly identifying each point of connection to the high-voltage section, shall be provided within sight of each point of connection. [495.25(B)](https://2023.antflix.net#495.25(B)) | https://2023.antflix.net#495.25(B) |
Chapter 4 Equipment for General Use | 495.30 | Part III covers assemblies of switchgear and industrial control equipment, including, but not limited to, switches and interrupting devices and their control, metering, protection, and regulating equipment where they are an integral part of the assembly, with associated interconnections and supporting structures. [495.30](https://2023.antflix.net#495.30) | https://2023.antflix.net#495.30 |
Chapter 4 Equipment for General Use | 495.31 | Arrangement of devices in assemblies shall be such that individual components can safely perform their intended function without adversely affecting the safe operation of other components in the assembly. [495.31](https://2023.antflix.net#495.31) | https://2023.antflix.net#495.31 |
Chapter 4 Equipment for General Use | 495.32 | Where access for other than visual inspection is required to a compartment that contains energized high-voltage parts, barriers shall be provided to prevent accidental contact by persons, tools, or other equipment with energized parts. Exposed live parts shall only be permitted in compartments accessible to qualified persons. Fuses and fuseholders designed to enable future replacement without de-energizing the fuseholder shall only be permitted for use by qualified persons. [495.32](https://2023.antflix.net#495.32) | https://2023.antflix.net#495.32 |
Chapter 4 Equipment for General Use | 495.33 | Energized bare parts mounted on doors shall be guarded where the door must be opened for maintenance of equipment or removal of draw-out equipment. [495.33](https://2023.antflix.net#495.33) | https://2023.antflix.net#495.33 |
Chapter 4 Equipment for General Use | 495.34 | The unobstructed space opposite terminals or opposite race-ways or cables entering a switchgear or control assembly shall be approved for the type of conductor and method of termination. [495.34](https://2023.antflix.net#495.34) | https://2023.antflix.net#495.34 |
Chapter 4 Equipment for General Use | 495.35(A) | Doors that would provide unqualified persons access to high-voltage energized parts shall be locked. Permanent signs in accordance with 110.21(B) shall be installed on panels or doors that provide access to live parts over 1000 volts and shall read DANGER - HIGH VOLTAGE - KEEP OUT. [495.35(A)](https://2023.antflix.net#495.35(A)) | https://2023.antflix.net#495.35(A) |
Chapter 4 Equipment for General Use | 495.35(B) | Where operating at 1000 volts, nominal, or less, control equipment, relays, motors, and the like shall not be installed in compartments with high-voltage parts or high-voltage wiring, unless both of the following apply: The access means is interlocked with the high-voltage switch or disconnecting means to prevent the access means from being opened or removed when the high-voltage switch is in the closed position or a withdrawable disconnecting means is in the connected position.All high-voltage parts or high-voltage wiring in the compartment that remains energized when a fixed mounted high-voltage switch is in the open position or a withdrawable disconnecting means is in the isolating (fully withdrawn) position are protected by insulating or grounded metal barriers to prevent accidental contact with energized high-voltage parts or wiring. [495.35(B)](https://2023.antflix.net#495.35(B)) | https://2023.antflix.net#495.35(B) |
Chapter 4 Equipment for General Use | 495.35(C) | High-voltage instrument or control transformers and space heaters shall be permitted to be installed in the high-voltage compartment without access restrictions beyond those that apply to the high-voltage compartment generally. [495.35(C)](https://2023.antflix.net#495.35(C)) | https://2023.antflix.net#495.35(C) |
Chapter 4 Equipment for General Use | 495.37 | The metal cases or frames, or both, such as those of instruments, relays, meters, and instrument and control transformers, located in or on switchgear or control assemblies, and the frames of switchgear and control assemblies shall be connected to an equipment grounding conductor or, where permitted, the grounded conductor, in accordance with 250.190. [495.37](https://2023.antflix.net#495.37) | https://2023.antflix.net#495.37 |
Chapter 4 Equipment for General Use | 495.38 | External hinged doors or covers shall be provided with stops to hold them in the open position. Cover plates intended to be removed for inspection of energized parts or wiring shall be equipped with lifting handles and shall not exceed 1.1 nr (12 ft2) in area or 27 kg (60 lb) in weight, unless they are hinged and bolted or locked. [495.38](https://2023.antflix.net#495.38) | https://2023.antflix.net#495.38 |
Chapter 4 Equipment for General Use | 495.39 | Gas discharged during operating of interrupting devices shall be directed so as not to endanger personnel. [495.39](https://2023.antflix.net#495.39) | https://2023.antflix.net#495.39 |
Chapter 4 Equipment for General Use | 495.40 | Windows intended for visual inspection of disconnecting switches or other devices shall be of suitable transparent material. [495.40](https://2023.antflix.net#495.40) | https://2023.antflix.net#495.40 |
Chapter 4 Equipment for General Use | 495.41 | Routinely operated industrial control equipment shall meet the requirements of 495.41 (A) unless infrequently operated, as covered in 495.41 (B). [495.41](https://2023.antflix.net#495.41) | https://2023.antflix.net#495.41 |
Chapter 4 Equipment for General Use | 495.41(A) | Control and instrument transfer switch handles or push buttons shall be in a readily accessible location at an elevation of not over 2.0 m (6 ft 7 in.). Exception: Operating handles requiring more than 23 kg (50 lb) of force shall be located no higher than 1.7 m (66 in.) in either the open or closed position. [495.41(A)](https://2023.antflix.net#495.41(A)) | https://2023.antflix.net#495.41(A) |
Chapter 4 Equipment for General Use | 495.41(B) | Where operating handles for such devices as draw-out fuses, fused potential or control transformers and their primary disconnects, and bus transfer and isolating switches are only operated infrequently, the handles shall be permitted to be located where they are safely operable and serviceable from a portable platform. [495.41(B)](https://2023.antflix.net#495.41(B)) | https://2023.antflix.net#495.41(B) |
Chapter 4 Equipment for General Use | 495.42 | Interrupter switches equipped with stored energy mechanisms shall have mechanical interlocks to prevent access to the switch compartment unless the stored energy mechanism is in the discharged or blocked position. [495.42](https://2023.antflix.net#495.42) | https://2023.antflix.net#495.42 |
Chapter 4 Equipment for General Use | 495.43 | The stored energy operator shall be permitted to be left in the uncharged position after the switch has been closed if a single movement of the operating handle charges the operator and opens the switch. [495.43](https://2023.antflix.net#495.43) | https://2023.antflix.net#495.43 |
Chapter 4 Equipment for General Use | 495.44(A) | The supply terminals of fused interrupter switches shall be installed at the top of the switch enclosure or, if the terminals are located elsewhere, the equipment shall have barriers installed to prevent persons from accidentally contacting energized parts or dropping tools or fuses into energized parts. [495.44(A)](https://2023.antflix.net#495.44(A)) | https://2023.antflix.net#495.44(A) |
Chapter 4 Equipment for General Use | 495.44(B) | Where fuses can be energized by backfeed, a sign shall be placed on the enclosure door identifying this hazard. [495.44(B)](https://2023.antflix.net#495.44(B)) | https://2023.antflix.net#495.44(B) |
Chapter 4 Equipment for General Use | 495.44(C) | The switching mechanism shall be arranged to be operated from a location outside the enclosure where the operator is not exposed to energized parts and shall be arranged to open all ungrounded conductors of the circuit simultaneously with one operation. Switches shall be lockable open in accordance with 110.25. [495.44(C)](https://2023.antflix.net#495.44(C)) | https://2023.antflix.net#495.44(C) |
Chapter 4 Equipment for General Use | 495.45(A) | Circuit breakers equipped with stored energy mechanisms shall be designed to prevent the release of the stored energy unless the mechanism has been fully charged. [495.45(A)](https://2023.antflix.net#495.45(A)) | https://2023.antflix.net#495.45(A) |
Chapter 4 Equipment for General Use | 495.45(B) | Mechanical interlocks shall be provided in the housing to prevent the complete withdrawal of the circuit breaker from the housing when the stored energy mechanism is in the fully charged position, unless a suitable device is provided to block the closing function of the circuit breaker before complete withdrawal. [495.45(B)](https://2023.antflix.net#495.45(B)) | https://2023.antflix.net#495.45(B) |
Chapter 4 Equipment for General Use | 495.46 | Circuit breakers shall be capable of being locked in the open position or, if they are installed in a draw-out mechanism, that mechanism shall be capable of being locked in such a position that the mechanism cannot be moved into the connected position. In either case, the provision for locking shall be lockable open in accordance with 110.25. [495.46](https://2023.antflix.net#495.46) | https://2023.antflix.net#495.46 |
Chapter 4 Equipment for General Use | 495.47 | Switchgear installed as high-voltage service equipment shall include a ground bus for the connection of service cable shields and to facilitate the attachment of safety grounds for personnel protection. This bus shall be extended into the compartment where the service conductors are terminated. Where the compartment door or panel provides access to parts that can only be de-energized and visibly isolated by the serving utility, the warning sign required by 495.35(A) shall include a notice that access is limited to the serving utility or is permitted only following an authorization of the serving utility. [495.47](https://2023.antflix.net#495.47) | https://2023.antflix.net#495.47 |
Chapter 4 Equipment for General Use | 495.48(A) | Substations shall be designed by a qualified licensed professional engineer. Where components or the entirety of the substation is listed by a qualified electrical testing laboratory, documentation of internal design features subject to the listing investigation shall not be required. The design shall address but not be limited to the following topics, and the documentation of this design shall be made available to the authority having jurisdiction: Clearances and exitsElectrical enclosuresSecuring and support of electrical equipmentFire protectionSafety ground connection provisionsGuarding live partsTransformers and voltage regulation equipmentConductor insulation, electrical and mechanical protection, isolation, and terminationsApplication, arrangement, and disconnection of circuit breakers, switches, and fusesProvisions for oil-filled equipmentSwitchgearOvervoltage (surge) protection equipment [495.48(A)](https://2023.antflix.net#495.48(A)) | https://2023.antflix.net#495.48(A) |
Chapter 4 Equipment for General Use | 495.48(B) | A permanent, single-line diagram of the switchgear shall be provided in a readily visible location within the same room or enclosed area with the switchgear and shall clearly identify the following: InterlocksIsolation meansAll possible sources of voltage to the installation under normal or emergency conditionsThe marking on the switchgear shall cross-reference the diagram.Exception: Where the equipment consists solely of a single cubicle or metal-enclosed substation containing only one high-voltage, switching device, diagrams shall not be required. [495.48(B)](https://2023.antflix.net#495.48(B)) | https://2023.antflix.net#495.48(B) |
Chapter 4 Equipment for General Use | 495.49 | Reconditioned switchgear, or sections of switchgear, shall be permitted. If equipment has been damaged by fire, products of combustion, or water, it shall be specifically evaluated by its manufacturer or a qualified testing laboratory prior to being returned to service. [495.49](https://2023.antflix.net#495.49) | https://2023.antflix.net#495.49 |
Chapter 4 Equipment for General Use | 495.61(A) | The provisions of this part shall apply to installations and use of high-voltage power distribution and utilization equipment that is portable, mobile, or both, and include but not be limited to the following: Substations and switch houses mounted on skidsTrailers or carsMobile shovelsDraglinesCranesHoistsDrillsDredgesCompressorsPumpsConveyorsUnderground excavators [495.61(A)](https://2023.antflix.net#495.61(A)) | https://2023.antflix.net#495.61(A) |
Chapter 4 Equipment for General Use | 495.61(B) | Grounding and bonding shall be in accordance with Part X of Article 250. [495.61(B)](https://2023.antflix.net#495.61(B)) | https://2023.antflix.net#495.61(B) |
Chapter 4 Equipment for General Use | 495.61(C) | Approved enclosures or guarding, or both, shall be provided to protect portable and mobile equipment from physical damage. [495.61(C)](https://2023.antflix.net#495.61(C)) | https://2023.antflix.net#495.61(C) |
Chapter 4 Equipment for General Use | 495.61(D) | Disconnecting means shall be installed for mobile and portable high-voltage equipment according to the requirements of Part VIII of Article 230 and shall disconnect all ungrounded conductors. [495.61(D)](https://2023.antflix.net#495.61(D)) | https://2023.antflix.net#495.61(D) |
Chapter 4 Equipment for General Use | 495.62 | Motors driving single or multiple dc generators supplying a system operating on a cyclic load basis shall not require overload protection if the thermal rating of the ac drive motor cannot be exceeded under any operating condition. The branch-circuit protective device(s) shall provide short-circuit and locked-rotor protection and shall be permitted to be external to the equipment. [495.62](https://2023.antflix.net#495.62) | https://2023.antflix.net#495.62 |
Chapter 4 Equipment for General Use | 495.63 | All energized switching and control parts shall be enclosed in grounded metal cabinets or enclosures. These cabinets or enclosures shall be marked DANGER - HIGH VOLTAGE - KEEP OUT and shall be locked so that only authorized and qualified persons can enter. The danger marking(s) or label(s) shall comply with 110.21(B). Circuit breakers and protective equipment shall have the operating means projecting through the metal cabinet or enclosure so these units can be reset without opening locked doors. With doors closed, safe access for normal operation of these units shall be provided. [495.63](https://2023.antflix.net#495.63) | https://2023.antflix.net#495.63 |
Chapter 4 Equipment for General Use | 495.64 | The collector ring assemblies on revolving-type machines (shovels, draglines, etc.) shall be guarded to prevent accidental contact with energized parts by personnel on or off the machine. [495.64](https://2023.antflix.net#495.64) | https://2023.antflix.net#495.64 |
Chapter 4 Equipment for General Use | 495.65 | A metallic enclosure shall be provided on the mobile machine for enclosing the terminals of the power cable. The enclosure shall include terminal connections to the machine frame for the equipment grounding conductor. Ungrounded conductors shall be attached to insulators or be terminated in approved high-voltage cable couplers (which include equipment grounding conductor connectors) of proper voltage and ampere rating. The method of cable termination used shall prevent any strain or pull on the cable from stressing the electrical connections. The enclosure shall have provision for locking so that only authorized and qualified persons can open it and shall be marked as follows: DANGER - HIGH VOLTAGE - KEEP OUT. The danger marking(s) or label(s) shall comply with 110.21(B). [495.65](https://2023.antflix.net#495.65) | https://2023.antflix.net#495.65 |
Chapter 4 Equipment for General Use | 495.66 | Flexible high-voltage cable supplying power to portable or mobile equipment shall comply with the grounding and bonding requirements in Parts V, VI, and X of Article 250 and the flexible cable requirements in Part III of Article 400. [495.66](https://2023.antflix.net#495.66) | https://2023.antflix.net#495.66 |
Chapter 4 Equipment for General Use | 495.70 | The provisions of Part V shall apply to boilers operating over 1000 volts, nominal, in which heat is generated by the passage of current between electrodes through the liquid being heated. [495.70](https://2023.antflix.net#495.70) | https://2023.antflix.net#495.70 |
Chapter 4 Equipment for General Use | 495.71 | Boilers shall be supplied only from a 3-phase, 4-wire solidly grounded wye system, or from isolating transformers arranged to provide such a system. Control circuit voltages shall not exceed 150 volts, shall be supplied from a grounded system, and shall have the controls in the ungrounded conductor. [495.71](https://2023.antflix.net#495.71) | https://2023.antflix.net#495.71 |
Chapter 4 Equipment for General Use | 495.72(A) | Each boiler shall be supplied from an individual branch circuit rated not less than 100 percent of the total load. [495.72(A)](https://2023.antflix.net#495.72(A)) | https://2023.antflix.net#495.72(A) |
Chapter 4 Equipment for General Use | 495.72(B) | The circuit shall be protected by a 3-phase, common-trip fault-interrupting device, which shall be permitted to automatically reclose the circuit upon removal of an overload condition but shall not reclose after a fault condition. [495.72(B)](https://2023.antflix.net#495.72(B)) | https://2023.antflix.net#495.72(B) |
Chapter 4 Equipment for General Use | 495.72(C) | Phase-fault protection shall be provided in each phase, consisting of a separate phase-overcurrent relay connected to a separate current transformer in the phase. [495.72(C)](https://2023.antflix.net#495.72(C)) | https://2023.antflix.net#495.72(C) |
Chapter 4 Equipment for General Use | 495.72(D) | Means shall be provided for detection of the sum of the neutral conductor and equipment grounding conductor currents and shall trip the circuit-interrupting device if the sum of those currents exceeds the greater of 5 amperes or 7 1/2 percent of the boiler full-load current for 10 seconds or exceeds an instantaneous value of 25 percent of the boiler full-load current. [495.72(D)](https://2023.antflix.net#495.72(D)) | https://2023.antflix.net#495.72(D) |
Chapter 4 Equipment for General Use | 495.72(E) | The grounded neutral conductor shall be as follows: Connected to the pressure vessel containing the heating elementsInsulated for not less than 1000 voltsHave not less than the ampacity of the largest ungrounded branch-circuit conductorInstalled with the ungrounded conductors in the same raceway, cable, or cable tray, or, where installed as open conductors, in close proximity to the ungrounded conductorsNot used for any other circuit [495.72(E)](https://2023.antflix.net#495.72(E)) | https://2023.antflix.net#495.72(E) |
Chapter 4 Equipment for General Use | 495.73 | Each boiler shall be equipped with a means to limit the maximum temperature, pressure, or both, by directly or indirectly interrupting all current flow through the heating elements. Such means shall be in addition to the temperature, pressure, or both, regulating systems and pressure relief or safety valves. [495.73](https://2023.antflix.net#495.73) | https://2023.antflix.net#495.73 |
Chapter 4 Equipment for General Use | 495.74 | All exposed non-current-carrying metal parts of the boiler and associated exposed metal structures or equipment shall be bonded to the pressure vessel or to the neutral conductor to which the vessel is connected in accordance with 250.102, except the ampacity of the bonding jumper shall not be less than the ampacity of the neutral conductor. [495.74](https://2023.antflix.net#495.74) | https://2023.antflix.net#495.74 |
Chaptewr 5 Special Occupancies | 500.1(A) | This article covers area classification and general requirements for electrical and electronic equipment and wiring rated at all voltages where fire or explosion hazards might exist due to flammable gases, flammable liquid—produced vapors, combustible liquid—produced vapors, combustible dusts, combustible fibers/flyings, or ignitible fibers/flyings in the following: Class I, Division 1 or Class I, Division 2 hazardous (classified) locationsClass II, Division 1 or Class II, Division 2 hazardous (classified) locationsClass III, Division 1 or Class III, Division 2 hazardous (classified) locationsInformational Note No. 1: See NFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, and NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, for extracted information referenced in brackets. Only editorial changes were made to the extracted text to make it consistent with this Code.Informational Note No. 2: See Article 100 for the definition of restricted industrial establishment [as applied to hazardous (classified) locations]. [500.1(A)](https://2023.antflix.net#500.1(A)) | https://2023.antflix.net#500.1(A) |
Chaptewr 5 Special Occupancies | 500.1(B) | This article does not cover electrical and electronic equipment and wiring rated at all voltages for the following: Zone 0, Zone 1, or Zone 2 hazardous (classified) locationsZone 20, Zone 21, or Zone 22 hazardous (classified) locationsLocations subject to the unique risk and explosion hazards associated with explosives, pyrotechnics, and blasting agentsLocations where pyrophoric materials are the only materials used or handledFeatures of equipment that involve nonelectrical potential sources of ignition (e.g., couplings, pumps, gearboxes, brakes, hydraulic and pneumatic motors, fans, engines, compressors)Informational Note No. 1: Common nonelectrical potential sources of ignition include hot surfaces and mechanically generated sparks.Informational Note No. 2: See ANSI/UL 80079-36, Explosive Atmospheres - Part 36: Non-Electrical Equipment for Explosive Atmospheres - Basic Method and Requirements, and ANSI/UL 80079-37, Explosive Atmospheres - Part 37: Non-Electrical Equipment for Explosive Atmospheres - Non-Electrical Type of Protection Constructional Safety "c" Control of Ignition Source "b", Liquid Immersion "k", for additional information. [500.1(B)](https://2023.antflix.net#500.1(B)) | https://2023.antflix.net#500.1(B) |
Chaptewr 5 Special Occupancies | 500.4 | Areas designated as hazardous (classified) locations or determined to be unclassified shall be documented on an area classification drawing and other associated documentation. This documentation shall be available to the authority having jurisdiction (AHJ) and those authorized to design, install, inspect, maintain, or operate electrical equipment at the location. Informational Note No. 1: See the following standards for additional information on the classification of locations:NFPA 30, Flammable and Combustible Liquids CodeNFPA 32, Standard for Drycleaning FacilitiesNFPA 33, Standard for Spray Application Using Flammable or Combustible MaterialsNFPA 34, Standard for Dipping, Coating, and Printing Processes Using Flammable or Combustible LiquidsNFPA 35, Standard for the Manufacture of Organic CoatingsNFPA 36, Standard for Solvent Extraction PlantsNFPA 45, Standard on Fire Protection for Laboratories Using ChemicalsNFPA 55, Compressed Gases and Cryogenic Fluids CodeNFPA 58, Liquefied Petroleum Gas CodeNFPA 59, Utility LP-Gas Plant CodeNFPA 497, Recommended Practice for the Classification of Flammable Liquids, Gases, or Vapors and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process AreasNFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process AreasNFPA 820, Standard for Fire Protection in Wastewater Treatment and Collection FacilitiesANSI/API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2ISA-12.10, Area Classification in Hazardous (Classified) Dust LocationsInformational Note No. 2: See NFPA 77, Recommended Practice on Static Electricity, NFPA 780, Standard for the Installation of Lightning Protection Systems; and API RP 2003, Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents, for information on protection against static electricity and lightning hazards in hazardous (classified) locations.Informational Note No. 3: See NFPA 30, Flammable and Combustible Liquids Code; and ANSI/API RP 500, Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division 1 and Division 2, for information on ventilation.Informational Note No. 4: See ANSI/API RP 14F, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Division 1, and Division 2 Locations, for information on electrical systems for hazardous (classified) locations on offshore oil- and gas-producing platforms, drilling rigs, and workover rigs.Informational Note No. 5: See ANSI/UL 121203, Portable/Personal Electronic Products Suitable for Use in Class I, Division 2, Class I, Zone 2, Class II, Division 2, Class III, Division 1, Class III, Division 2, Zone 21 and Zone 22 Hazardous (Classified) Locations, for information on portable or transportable equipment having self-contained power supplies, such as battery-operated equipment, which could potentially become an ignition source in hazardous (classified) locations.Informational Note No. 6: See IEC/IEEE 60079-30-2, Explosive atmospheres - Part 30-2: Electrical resistance trace heating - Application guide for design, installation and maintenance, for information on electrical resistance trace heating for hazardous (classified) locations.Informational Note No. 7: See IEEE 844.2/CSA C293.2, IEEE/CSA Standard for Skin Effect Trace Heating of Pipelines, Vessels, Equipment, and Structures - Application Guide for Design, Installation, Testing, Commissioning, and Maintenance, for information on electric skin effect trace heating for hazardous (classified) locations.Informational Note No. 8: See IEEE 844.4/CSA C293.4, IEEE/CSA Standard for Impedance Heating of Pipelines and Equipment - Application Guide for Design, Installation, Testing, Commissioning, and Maintenance, for information on electric impedance heating for hazardous (classified) locations. [500.4](https://2023.antflix.net#500.4) | https://2023.antflix.net#500.4 |
Chaptewr 5 Special Occupancies | 500.5(A)(1) | Locations shall be classified depending on the properties of the flammable gas, flammable liquid—produced vapor, combustible liquid—produced vapors, combustible dusts, or fibers/flyings that could be present, and the likelihood that a flammable or combustible concentration or quantity is present. Each room, section, or area shall be considered individually in determining its classification. Informational Note: Through the exercise of ingenuity in the layout of electrical installations for hazardous (classified) locations, it is frequently possible to locate much of the equipment in a reduced level of classification or in an unclassified location to reduce the amount of special equipment required. [500.5(A)(1)](https://2023.antflix.net#500.5(A)(1)) | https://2023.antflix.net#500.5(A)(1) |
Chaptewr 5 Special Occupancies | 500.5(A)(2) | Refrigerant machinery rooms that contain ammonia refrigeration systems and are equipped with adequate mechanical ventilation that operates continuously or is initiated by a detection system at a concentration not exceeding 150 ppm shall be permitted to be classified as "unclassified" locations. Informational Note: See ANSI/IIAR 2, Standard for Design of Safe Closed-Circuit Ammonia Refrigeration Systems, for information on classification and ventilation of areas involving closed-circuit ammonia refrigeration systems. [500.5(A)(2)](https://2023.antflix.net#500.5(A)(2)) | https://2023.antflix.net#500.5(A)(2) |
Chaptewr 5 Special Occupancies | 500.5(B) | Class I locations are those in which flammable gases, flammable liquid—produced vapors, or combustible liquid—produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures. Class I locations shall include those specified in 500.5(B)(1) and (B)(2). [500.5(B)](https://2023.antflix.net#500.5(B)) | https://2023.antflix.net#500.5(B) |
Chaptewr 5 Special Occupancies | 500.5(B)(1) | A Class I, Division 1 location is a location: In which ignitible concentrations of flammable gases, flammable liquid—produced vapors, or combustible liquid—produced vapors can exist under normal operating conditions, orIn which ignitible concentrations of such flammable gases, flammable liquid—produced vapors, or combustible liquids above their flash points might exist frequently because of repair or maintenance operations or because of leakage, orIn which breakdown or faulty operation of equipment or processes might release ignitible concentrations of flammable gases, flammable liquid—produced vapors, or combustible liquid—produced vapors and might also cause simultaneous failure of electrical equipment in such a way as to directly cause the electrical equipment to become a source of ignitionInformational Note: This classification usually includes the following locations:Where volatile flammable liquids or liquefied flammable gases are transferred from one container to anotherInteriors of spray booths and areas in the vicinity of spraying and painting operations where volatile flammable solvents are usedLocations containing open tanks or vats of volatile flammable liquidsDrying rooms or compartments for the evaporation of flammable solventsLocations containing fat- and oil-extraction equipment using volatile flammable solventsPortions of cleaning and dyeing plants where flammable liquids are usedGas generator rooms and other portions of gas manufacturing plants where flammable gas might escapeInadequately ventilated pump rooms for flammable gas or for volatile flammable liquidsInteriors of refrigerators and freezers in which volatile flammable materials are stored in open, lightly stoppered, or easily ruptured containersInside of inadequately vented enclosures containing instruments normally venting flammable gases or vapors to the interior of the enclosureInside of vented tanks containing volatile flammable liquidsArea between inner and outer roof sections of floating roof tanks containing volatile flammable fluidsInadequately ventilated areas within spraying or coating operations using volatile flammable fluidsInterior of exhaust ducts used to vent ignitible concentrations of gases or vaporsAll other locations where ignitible concentrations of flammable vapors or gases are likely to occur during normal operationsExperience has demonstrated the prudence of avoiding the installation of instrumentation or other electrical equipment in the areas covered in list items (11) through (15). Where it cannot be avoided because it is essential to the process and other locations are not feasible electrical equipment or instrumentation approved for the specific application or consisting of intrinsically safe systems might be considered. [500.5(B)(1)](https://2023.antflix.net#500.5(B)(1)) | https://2023.antflix.net#500.5(B)(1) |
Chaptewr 5 Special Occupancies | 500.5(B)(2) | A Class I, Division 2 location is a location: In which volatile flammable gases, flammable liquid-produced vapors, or combustible liquid—produced vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can escape only in case of accidental rupture or breakdown of such containers or systems or in case of abnormal operation of equipment, orIn which ignitible concentrations of flammable gases, flammable liquid—produced vapors, or combustible liquid—produced vapors are normally prevented by positive mechanical ventilation and which might become hazardous through failure or abnormal operation of the ventilating equipment, orThat is adjacent to a Class I, Division 1 location, and to which ignitible concentrations of flammable gases, flammable liquid—produced vapors, or combustible liquid-produced vapors above their flash points might occasionally be communicated unless such communication is prevented by adequate positive-pressure ventilation from a source of clean air and effective safeguards against ventilation failure are provided.Informational Note No. 1: This classification usually includes locations where volatile flammable liquids or flammable gases or vapors are used but that, in the judgment of the authority having jurisdiction, would become hazardous only in case of an accident or of some unusual operating condition. The quantity of flammable material that might escape in case of accident, the adequacy of ventilating equipment, the total area involved, and the record of the industry or business with respect to explosions or fires are all factors that merit consideration in determining the classification and extent of each location.Informational Note No. 2: See NFPA 30, Flammable and Combustible Liquids Code, and NFPA 58, Liquefied Petroleum Gas Code. Piping without valves, checks, meters, and similar devices would not ordinarily introduce a hazardous condition even if used for flammable liquids or gases. Depending on factors such as the quantity and size of the containers and ventilation, locations used for the storage of flammable liquids or liquefied or compressed gases in sealed containers might be considered either hazardous (classified) or unclassified locations. [500.5(B)(2)](https://2023.antflix.net#500.5(B)(2)) | https://2023.antflix.net#500.5(B)(2) |
Chaptewr 5 Special Occupancies | 500.5(C) | Class II locations are those that are hazardous because of the presence of combustible dust. Class II locations shall include those specified in 500.5(C)(1) and (C)(2). [500.5(C)](https://2023.antflix.net#500.5(C)) | https://2023.antflix.net#500.5(C) |
Chaptewr 5 Special Occupancies | 500.5(C)(1) | A Class II, Division 1 location is a location: In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitible mixtures, orWhere mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitible mixtures to be produced, and might also provide a source of ignition through simultaneous failure of electrical equipment, through operation of protection devices, or from other causes, orIn which Group E combustible dusts may be present in quantities sufficient to be hazardous in normal or abnormal operating conditions.Informational Note: Dusts containing magnesium or aluminum are particularly hazardous, and the use of extreme precaution is necessary to avoid ignition and explosion. [500.5(C)(1)](https://2023.antflix.net#500.5(C)(1)) | https://2023.antflix.net#500.5(C)(1) |
Chaptewr 5 Special Occupancies | 500.5(C)(2) | A Class II, Division 2 location is a location: In which combustible dust due to abnormal operations may be present in the air in quantities sufficient to produce explosive or ignitible mixtures; orWhere combustible dust accumulations are present but are normally insufficient to interfere with the normal operation of electrical equipment or other apparatus, but could as a result of infrequent malfunctioning of handling or processing equipment become suspended in the air; orIn which combustible dust accumulations on, in, or in the vicinity of the electrical equipment could be sufficient to interfere with the safe dissipation of heat from electrical equipment, or could be ignitible by abnormal operation or failure of electrical equipment.Informational Note No. 1: The quantity of combustible dust that may be present and the adequacy of dust removal systems are factors that merit consideration in determining the classification and may result in an unclassified area.Informational Note No. 2: Where products such as seed are handled in a manner that produces low quantities of dust, the amount of dust deposited may not warrant classification. [500.5(C)(2)](https://2023.antflix.net#500.5(C)(2)) | https://2023.antflix.net#500.5(C)(2) |
Chaptewr 5 Special Occupancies | 500.5(D) | Class III locations shall be locations meeting the requirements of 500.5(D)(1) and (D)(2). [500.5(D)](https://2023.antflix.net#500.5(D)) | https://2023.antflix.net#500.5(D) |
Chaptewr 5 Special Occupancies | 500.5(D)(1) | Class III, Division 1 locations shall include those locations specified in 500.5(D)(1)(a) and (D)(1)(b). Combustible Fibers/Flyings. Locations where nonmetal combustible fibers/flyings are in the air under normal operating conditions in quantities sufficient to produce explosible mixtures or where mechanical failure or abnormal operation of machinery or equipment might cause combustible fibers/flyings to be produced and might also provide a source of ignition through simultaneous failure of electrical equipment, through operation of protection devices, or from other causes shall be classified as Class III, Division 1. Locations where metal combustible fibers/flyings are present shall be classified as Class II, Division 1, Group E.Informational Note No. 1: Such locations usually include some parts of rayon, cotton, and other textile mills; associated manufacturing and processing plants; cotton gins and cottonseed mills; flax-processing plants; clothing manufacturing plants; woodworking plants; and establishments and industries involving similar hazardous processes or conditions.Informational Note No. 2: Combustible fibers/flyings include flat platelet-shaped particulates, such as metal flakes, and fibrous board, such as particle board.Ignitible Fibers/Flyings. Locations where ignitible fibers/flyings are handled, manufactured, or used shall be classified as Class III, Division 1.Informational Note No. 1: Such locations usually include some parts of rayon, cotton, and other textile mills; associated manufacturing and processing plants; cotton gins and cotton-seed mills; flax-processing plants; clothing manufacturing plants; woodworking plants; and establishments and industries involving similar hazardous processes or conditions.Informational Note No. 2: Ignitible fibers/flyings can include rayon, cotton (including cotton linters and cotton waste), sisal or henequen, istle, jute, hemp, tow, cocoa fiber, oakum, baled waste kapok, Spanish moss, excelsior, and other materials of similar nature. [500.5(D)(1)](https://2023.antflix.net#500.5(D)(1)) | https://2023.antflix.net#500.5(D)(1) |
Chaptewr 5 Special Occupancies | 500.5(D)(2) | Class III, Division 2 locations shall include those locations specified in 500.5(D)(2)(a) and (D)(2)(b). Combustible Fibers/Flyings. Locations where nonmetal combustible fibers/flyings might be present in the air in quantities sufficient to produce explosible mixtures due to abnormal operations or where accumulations of nonmetal combustible fibers/flyings accumulations are present but are insufficient to interfere with the normal operation of electrical equipment or other apparatus but could, as a result of infrequent malfunctioning of handling or processing equipment, become suspended in the air shall be classified as Class III, Division 2.Ignitible Fibers/Flyings. Locations where ignitible fibers/flyings are stored or handled, other than in the process of manufacture, shall be classified as Class III, Division 2. [500.5(D)(2)](https://2023.antflix.net#500.5(D)(2)) | https://2023.antflix.net#500.5(D)(2) |
Chaptewr 5 Special Occupancies | 500.6(A) | Class I groups shall be in accordance with 500.6(A)(1) through (A)(4). Informational Note No. 1: The explosion characteristics of air mixtures of gases or vapors vary with the specific material involved. For Class I locations, Groups A, B, C, and D, the classification involves determinations of maximum explosion pressure and maximum safe clearance between parts of a clamped joint in an enclosure. It is necessary, therefore, that equipment be identified not only for class but also for the specific group of the gas or vapor that will be present. Informational Note No. 2: Certain chemical atmospheres may have characteristics that require safeguards beyond those required for any of the Class I groups. Carbon disulfide is one of these chemicals because of its low autoignition temperature (90°C) and the small joint clearance permitted to arrest its flame. [500.6(A)](https://2023.antflix.net#500.6(A)) | https://2023.antflix.net#500.6(A) |
Chaptewr 5 Special Occupancies | 500.6(A)(1) | Acetylene. [497:3.3.5.1.1] [500.6(A)(1)](https://2023.antflix.net#500.6(A)(1)) | https://2023.antflix.net#500.6(A)(1) |
Chaptewr 5 Special Occupancies | 500.6(A)(2) | Flammable gas, flammable liquid—produced vapor, or combustible liquid—produced vapor mixed with air that may burn or explode, having either a maximum experimental safe gap (MESG) value less than or equal to 0.45 mm or a minimum igniting current ratio (MIC ratio) less than or equal to 0.40. [497:3.3.5.1.2] Informational Note: A typical Class I, Group B material is hydrogen. [500.6(A)(2)](https://2023.antflix.net#500.6(A)(2)) | https://2023.antflix.net#500.6(A)(2) |
Chaptewr 5 Special Occupancies | 500.6(A)(3) | Flammable gas, flammable liquid—produced vapor, or combustible liquid—produced vapor mixed with air that may burn or explode, having either a maximum experimental safe gap (MESG) value greater than 0.45 mm and less than or equal to 0.75 mm, or a minimum igniting current (MIC) ratio greater than 0.40 and less than or equal to 0.80. [497:3.3.5.1.3] Informational Note: A typical Class I, Group C material is ethylene. [500.6(A)(3)](https://2023.antflix.net#500.6(A)(3)) | https://2023.antflix.net#500.6(A)(3) |
Chaptewr 5 Special Occupancies | 500.6(A)(4) | Flammable gas, flammable liquid—produced vapor, or combustible liquid—produced vapor mixed with air that may burn or explode, having either a maximum experimental safe gap (MESG) value greater than 0.75 mm or a minimum igniting current (MIC) ratio greater than 0.80. [497:3.3.5.1.4] Informational Note No. 1: A typical Class I, Group D material is propane. [497:3.3.5.1.4] Informational Note No. 2: See ANSI/ASHRAE 15, Safety Standard for Refrigeration Systems, for information on the classification of areas involving ammonia atmospheres. [500.6(A)(4)](https://2023.antflix.net#500.6(A)(4)) | https://2023.antflix.net#500.6(A)(4) |
Chaptewr 5 Special Occupancies | 500.6(B) | Combustible dust shall be grouped in accordance with 500.6(B)(1) through (B)(3). [500.6(B)](https://2023.antflix.net#500.6(B)) | https://2023.antflix.net#500.6(B) |
Chaptewr 5 Special Occupancies | 500.6(B)(1) | Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment. [499:3.3.8.1.1] Informational Note: Certain metal dusts may have characteristics that require safeguards beyond those required for atmospheres containing the dusts of aluminum, magnesium, and their commercial alloys. For example, zirconium, thorium, and uranium dusts have extremely low ignition temperatures [as low as 20°C (68°F)] and minimum ignition energies lower than any material classified in any of the Class I or Class II groups. [500.6(B)(1)](https://2023.antflix.net#500.6(B)(1)) | https://2023.antflix.net#500.6(B)(1) |
Chaptewr 5 Special Occupancies | 500.6(B)(2) | Atmospheres containing combustible carbonaceous dusts that have more than 8 percent total entrapped volatiles (see ASTM D3175-2017, Standard Test Method for Volatile Matter in the Analysis Sample of Coal and Coke, for coal and coke dusts) or that have been sensitized by other materials so that they present an explosion hazard. [499:3.3.8.1.2] Coal, carbon black, charcoal, and coke dusts are examples of carbonaceous dusts. [499:A.3.3.8.1.2] Informational Note: Testing of specific dust samples, following established ASTM testing procedures, is a method used to identify the combustibility of a specific dust and the need to classify those locations containing that material as Group F. [500.6(B)(2)](https://2023.antflix.net#500.6(B)(2)) | https://2023.antflix.net#500.6(B)(2) |
Chaptewr 5 Special Occupancies | 500.6(B)(3) | Atmospheres containing combustible dusts not included in Group E or Group F, including flour, grain, wood, plastic, and chemicals. [499:3.3.8.1.3] Informational Note No. 1: See NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, for information on group classification of Class II materials. Informational Note No. 2: The explosion characteristics of air mixtures of dust vary with the materials involved. For Class II locations, Groups E, F, and G, the classification involves the tightness of the joints of assembly and shaft openings to prevent the entrance of dust in the dust-ignitionproof enclosure, the blanketing effect of layers of dust on the equipment that may cause overheating, and the ignition temperature of the dust. It is necessary, therefore, that equipment be identified not only for the class but also for the specific group of dust that will be present. Informational Note No. 3: See ANSI/IEEE C2, National Electrical Safety Code, Section 127A, Coal Handling Areas. Certain dusts might require additional precautions due to chemical phenomena that can result in the generation of ignitible gases. [500.6(B)(3)](https://2023.antflix.net#500.6(B)(3)) | https://2023.antflix.net#500.6(B)(3) |
Chaptewr 5 Special Occupancies | 500.6(C) | Combustible fibers/flyings shall not be further grouped. [500.6(C)](https://2023.antflix.net#500.6(C)) | https://2023.antflix.net#500.6(C) |
Chaptewr 5 Special Occupancies | 500.6(D) | Ignitible fibers/flyings shall not be further grouped. [500.6(D)](https://2023.antflix.net#500.6(D)) | https://2023.antflix.net#500.6(D) |
Chaptewr 5 Special Occupancies | 500.7 | Electrical and electronic equipment in hazardous (classified) locations shall be protected by one or more of the techniques in 500.7(A) through (P). Suitability of the protection techniques for specific hazardous locations is shown in Chapter 9, Table 13. [500.7](https://2023.antflix.net#500.7) | https://2023.antflix.net#500.7 |
Chaptewr 5 Special Occupancies | 500.7(A) | This protection technique shall be permitted for equipment in Class I, Division 1 or 2 locations. [500.7(A)](https://2023.antflix.net#500.7(A)) | https://2023.antflix.net#500.7(A) |
Chaptewr 5 Special Occupancies | 500.7(B) | This protection technique shall be permitted for equipment in Class II, Division 1 or 2 locations. [500.7(B)](https://2023.antflix.net#500.7(B)) | https://2023.antflix.net#500.7(B) |
Chaptewr 5 Special Occupancies | 500.7(C) | This protection technique shall be permitted for equipment in Class II, Division 2 or Class III, Division 1 or 2 locations. [500.7(C)](https://2023.antflix.net#500.7(C)) | https://2023.antflix.net#500.7(C) |
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