Chapter stringclasses 6 values | Reference stringlengths 1 17 | Body stringlengths 62 23.1k | URL stringlengths 26 42 |
|---|---|---|---|
Chapter 4 Equipment for General Use | 440.22(B) | The equipment branch-circuit short-circuit and ground-fault protective device shall be capable of carrying the starting current of the equipment. Where the hermetic refrigerant motor-compressor is the only load on the circuit, the protection shall comply with 440.22(A). Where the equipment incorporates more than one hermetic refrigerant motor-compressor or a hermetic refrigerant motor-compressor and other motors or other loads, the equipment short-circuit and ground-fault protection shall comply with 430.53 and 440.22(B)(1) and (B)(2). [440.22(B)](https://2023.antflix.net#440.22(B)) | https://2023.antflix.net#440.22(B) |
Chapter 4 Equipment for General Use | 440.22(B)(1) | Where a hermetic refrigerant motor-compressor is the largest load connected to the circuit, the rating or setting of the branch-circuit short-circuit and ground-fault protective device shall not exceed the value specified in 440.22(A) for the largest motor-compressor plus the sum of the rated-load current or branch-circuit selection current, whichever is greater, of the other motor-compressor(s) and the ratings of the other loads supplied. [440.22(B)(1)](https://2023.antflix.net#440.22(B)(1)) | https://2023.antflix.net#440.22(B)(1) |
Chapter 4 Equipment for General Use | 440.22(B)(2) | Where a hermetic refrigerant motor-compressor is not the largest load connected to the circuit, the rating or setting of the branch-circuit short-circuit and ground-fault protective device shall not exceed a value equal to the sum of the rated-load current or branch-circuit selection current, whichever is greater, rating(s) for the motor-compressor(s) plus the value specified in 430.53(C)(4) where other motor loads are supplied, or the value specified in 240.4 where only nonmotor loads are supplied in addition to the motor-compressor(s). Exception No. 1: Equipment that starts and operates on a 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt single-phase branch circuit, shall be permitted to be protected by the 15- or 20-ampere over-current device protecting the branch circuit, but if the maximum branch-circuit short-circuit and ground-fault protective device rating marked on the equipment is less than these values, the circuit protective device shall not exceed the value marked on the equipment nameplate. Exception No. 2: The nameplate marking of cord-and-plug-connected equipment rated not greater than 250 volts, single-phase, such as household refrigerators and freezers, drinking water coolers, and beverage dispensers, shall be used in determining the branch-circuit requirements, and each unit shall be considered as a single motor unless the nameplate is marked otherwise. [440.22(B)(2)](https://2023.antflix.net#440.22(B)(2)) | https://2023.antflix.net#440.22(B)(2) |
Chapter 4 Equipment for General Use | 440.22(C) | Where maximum protective device ratings shown on a manufacturer's overload relay table for use with a motor controller are less than the rating or setting selected in accordance with 440.22(A) and (B), the protective device rating shall not exceed the manufacturer's values marked on the equipment. [440.22(C)](https://2023.antflix.net#440.22(C)) | https://2023.antflix.net#440.22(C) |
Chapter 4 Equipment for General Use | 440.31 | Part IV and adjustments made in accordance with Part III of Article 310 specify ampacities of conductors required to carry the motor current without overheating under the conditions specified, except as modified in 440.6(A), Exception No. 1. These articles shall not apply to integral conductors of motors, to motor controllers and the like, or to conductors that form an integral part of approved equipment. [440.31](https://2023.antflix.net#440.31) | https://2023.antflix.net#440.31 |
Chapter 4 Equipment for General Use | 440.32 | Branch-circuit conductors supplying a single motor-compressor shall have an ampacity not less than the greater of the following: 125 percent of the motor-compressor rated-load current125 percent of the branch-circuit selection currentFor a wye-start, delta-run connected motor-compressor, the selection of branch-circuit conductors between the motor controller and the motor-compressor shall be permitted to be based on 72 percent of either the motor-compressor rated-load current or the branch-circuit selection current, whichever is greater.Informational Note: The multiplier of 72 percent is obtained by multiplying 58 percent by 1.25 because the individual motor circuit conductors of wye-start, delta-run connected motor-compressors carry 58 percent of the rated-load current. [440.32](https://2023.antflix.net#440.32) | https://2023.antflix.net#440.32 |
Chapter 4 Equipment for General Use | 440.33 | Conductors supplying one or more motor-compressor(s) with or without an additional motor load(s) shall have an ampacity not less than the sum of each of the following: The sum of the rated-load or branch-circuit selection current, whichever is greater, of all motor-compressor(s)The sum of the full-load current rating of all other motors25 percent of the highest motor-compressor or motor full load current in the groupException No. 1: Where the circuitry is interlocked so as to prevent the starting and running of a second motor-compressor or group of motor-compressors, the conductor size shall be determined from the largest motor-compressor or group of motor-compressors that is to be operated at a given time.Exception No. 2: The branch-circuit conductors for room air conditioners shall be in accordance with Part VII of Article 440. [440.33](https://2023.antflix.net#440.33) | https://2023.antflix.net#440.33 |
Chapter 4 Equipment for General Use | 440.34 | Conductors supplying a motor-compressor load(s) in addition to other load(s) shall have an ampacity sufficient for the other load(s) plus the required ampacity for the motor-compressor load(s).The motor compressor load(s) shall be determined in accordance with 440.32 or 440.33. The other load(s) shall be calculated from branch-circuit, feeder, and service load calculations. Exception: Where the circuitry is interlocked to prevent simultaneous operation of the motor-compressor(s) and all other loads connected, the conductor size shall be determined from the largest size required for the motor-compressor(s) and other loads to be operated at a given time. [440.34](https://2023.antflix.net#440.34) | https://2023.antflix.net#440.34 |
Chapter 4 Equipment for General Use | 440.35 | The ampacity of the conductors supplying multimotor and combination-load equipment shall not be less than the minimum circuit ampacity marked on the equipment in accordance with 440.4(B). [440.35](https://2023.antflix.net#440.35) | https://2023.antflix.net#440.35 |
Chapter 4 Equipment for General Use | 440.41(A) | A motor-compressor controller shall have both a continuous-duty full-load current rating and a locked-rotor current rating not less than the name-plate rated-load current or branch-circuit selection current, whichever is greater, and locked-rotor current, respectively, of the compressor. In case the motor controller is rated in horsepower but is without one or both of the foregoing current ratings, equivalent currents shall be determined from the ratings as follows. Table 430.248, Table 430.249, and Table 430.250 shall be used to determine the equivalent full-load current rating. Table 430.251(A) and Table 430.251(B) shall be used to determine the equivalent locked-rotor current ratings. [440.41(A)](https://2023.antflix.net#440.41(A)) | https://2023.antflix.net#440.41(A) |
Chapter 4 Equipment for General Use | 440.41(B) | A controller serving more than one motor-compressor or a motor-compressor and other loads shall have a continuous-duty full-load current rating and a locked-rotor current rating not less than the combined load as determined in accordance with 440.12(B). [440.41(B)](https://2023.antflix.net#440.41(B)) | https://2023.antflix.net#440.41(B) |
Chapter 4 Equipment for General Use | 440.51 | Part VI specifies devices intended to protect the motor-compressor, the motor-control apparatus, and the branch-circuit conductors against excessive heating due to motor overload and failure to start. Informational Note: See 240.4(G) for application of Parts III and VI of Article 440. [440.51](https://2023.antflix.net#440.51) | https://2023.antflix.net#440.51 |
Chapter 4 Equipment for General Use | 440.52(A) | Each motor-compressor shall be protected against overload and failure to start by one of the following means: A separate overload relay that is responsive to motor-compressor current. This device shall be selected to trip at not more than 140 percent of the motor-compressor rated-load current.A thermal protector integral with the motor-compressor, approved for use with the motor-compressor that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and its control circuit is operated by a protective device integral with the motor-compressor, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor-compressor.A fuse or inverse time circuit breaker responsive to motor current, which shall also be permitted to serve as the branch-circuit short-circuit and ground-fault protective device. This device shall be rated at not more than 125 percent of the motor-compressor rated-load current. It shall have sufficient time delay to permit the motor-compressor to start and accelerate its load. The equipment or the motor-compressor shall be marked with this maximum branch-circuit fuse or inverse time circuit breaker rating.A protective system, furnished or specified and approved for use with the motor-compressor that it protects on the basis that it will prevent dangerous overheating of the motor-compressor due to overload and failure to start. If the current-interrupting device is separate from the motor-compressor and its control circuit is operated by a protective device that is not integral with the current-interrupting device, it shall be arranged so that the opening of the control circuit will result in interruption of current to the motor-compressor. [440.52(A)](https://2023.antflix.net#440.52(A)) | https://2023.antflix.net#440.52(A) |
Chapter 4 Equipment for General Use | 440.52(B) | The motor-compressor controller(s), the disconnecting means, and the branch-circuit conductors shall be protected against overcurrent due to motor overload and failure to start by one of the following means, which shall be permitted to be the same device or system protecting the motor-compressor in accordance with 440.52(A):
Exception: Overload protection of motor-compressors and equipment on 15- and 20-ampere, single-phase, branch circuits shall be permitted to be in accordance with 440.54 and 440.55.
An overload relay selected in accordance with 440.52(A)(1)
A thermal protector applied in accordance with 440.52(A)(2), that will not permit a continuous current in excess of 156 percent of the marked rated-load current or branch-circuit selection current
A fuse or inverse time circuit breaker selected in accordance with 440.52(A)(3)
A protective system, in accordance with 440.52(A)(4), that will not permit a continuous current in excess of 156 percent of the marked rated-load current or branch-circuit selection current
[440.52(B)](https://2023.antflix.net#440.52(B)) | https://2023.antflix.net#440.52(B) |
Chapter 4 Equipment for General Use | 440.53 | Overload relays and other devices for motor overload protection that are not capable of opening short circuits shall be protected by fuses or inverse time circuit breakers with ratings or settings in accordance with Part III unless identified for group installation or for part-winding motors and marked to indicate the maximum size of fuse or inverse time circuit breaker by which they shall be protected. Exception: The fuse or inverse time circuit breaker size marking shall be permitted on the nameplate of the equipment in which the overload relay or other overload device is used. [440.53](https://2023.antflix.net#440.53) | https://2023.antflix.net#440.53 |
Chapter 4 Equipment for General Use | 440.54 | Overload protection for motor-compressors and equipment used on 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt, single-phase branch circuits shall be permitted in accordance with 440.54(A) and (B). [440.54](https://2023.antflix.net#440.54) | https://2023.antflix.net#440.54 |
Chapter 4 Equipment for General Use | 440.54(A) | The motor-compressor shall be provided with overload protection selected as specified in 440.52(A). Both the controller and motor overload protective device shall be identified for installation with the short-circuit and ground-fault protective device for the branch circuit to which the equipment is connected. [440.54(A)](https://2023.antflix.net#440.54(A)) | https://2023.antflix.net#440.54(A) |
Chapter 4 Equipment for General Use | 440.54(B) | The short-circuit and ground-fault protective device protecting the branch circuit shall have sufficient time delay to permit the motor-compressor and other motors to start and accelerate their loads. [440.54(B)](https://2023.antflix.net#440.54(B)) | https://2023.antflix.net#440.54(B) |
Chapter 4 Equipment for General Use | 440.55 | Overload protection for motor-compressors and equipment that are cord- and attachment-plug-connected and used on 15- or 20-ampere 120-volt, or 15-ampere 208- or 240-volt, single-phase branch circuits shall be permitted in accordance with 440.55(A), (B), and (C). [440.55](https://2023.antflix.net#440.55) | https://2023.antflix.net#440.55 |
Chapter 4 Equipment for General Use | 440.55(A) | The motor-compressor shall be provided with overload protection as specified in 440.52(A). Both the controller and the motor overload protective device shall be identified for installation with the short-circuit and ground-fault protective device for the branch circuit to which the equipment is connected. [440.55(A)](https://2023.antflix.net#440.55(A)) | https://2023.antflix.net#440.55(A) |
Chapter 4 Equipment for General Use | 440.55(B) | The rating of the attachment plug and receptacle or cord connector shall not exceed 20 amperes at 125 volts or 15 amperes at 250 volts. [440.55(B)](https://2023.antflix.net#440.55(B)) | https://2023.antflix.net#440.55(B) |
Chapter 4 Equipment for General Use | 440.55(C) | The short-circuit and ground-fault protective device protecting the branch circuit shall have sufficient time delay to permit the motor-compressor and other motors to start and accelerate their loads. [440.55(C)](https://2023.antflix.net#440.55(C)) | https://2023.antflix.net#440.55(C) |
Chapter 4 Equipment for General Use | 440.60 | Part VII shall apply to electrically energized room air conditioners that control temperature and humidity. For the purpose of Part VII, a room air conditioner (with or without provisions for heating) shall be considered as an ac appliance of the air-cooled window, console, or in-wall type that is installed in the conditioned room and that incorporates a hermetic refrigerant motor-compressor(s). Part VII covers equipment rated not over 250 volts, single phase, and the equipment shall be permitted to be cord- and attachment-plug-connected. A room air conditioner that is rated 3-phase or rated over 250 volts shall be directly connected to a wiring method recognized in Chapter 3, and Part VII shall not apply. [440.60](https://2023.antflix.net#440.60) | https://2023.antflix.net#440.60 |
Chapter 4 Equipment for General Use | 440.61 | The enclosures of room air conditioners shall be connected to the equipment grounding conductor in accordance with 250.110, 250.112, and 250.114. [440.61](https://2023.antflix.net#440.61) | https://2023.antflix.net#440.61 |
Chapter 4 Equipment for General Use | 440.62(A) | A room air conditioner shall be considered as a single motor unit in determining its branch-circuit requirements where all the following conditions are met: It is cord- and attachment-plug-connected.Its rating is not more than 40 amperes and 250 volts, single phase.Total rated-load current is shown on the room airconditioner nameplate rather than individual motor currents.The rating of the branch-circuit short-circuit and ground-fault protective device does not exceed the ampacity of the branch-circuit conductors or the rating of the receptacle, whichever is less. [440.62(A)](https://2023.antflix.net#440.62(A)) | https://2023.antflix.net#440.62(A) |
Chapter 4 Equipment for General Use | 440.62(B) | The total marked current rating of a cord- and attachment-plug-connected room air conditioner shall not exceed 80 percent of the current rating of a branch circuit where no other loads are supplied. [440.62(B)](https://2023.antflix.net#440.62(B)) | https://2023.antflix.net#440.62(B) |
Chapter 4 Equipment for General Use | 440.62(C) | The total marked current rating of a cord- and attachment-plug-connected room air conditioner shall not exceed 50 percent of the current rating of a branch circuit where lighting outlets, other appliances, or general-use receptacles are also supplied. Where the circuitry is interlocked to prevent simultaneous operation of the room air conditioner and energization of other outlets on the same branch circuit, a cord- and attachment-plug-connected room air conditioner shall not exceed 80 percent of the branch-circuit current rating. [440.62(C)](https://2023.antflix.net#440.62(C)) | https://2023.antflix.net#440.62(C) |
Chapter 4 Equipment for General Use | 440.63 | An attachment plug and receptacle or cord connector shall be permitted to serve as the disconnecting means for a single-phase room air conditioner rated 250 volts or less if (1) the manual controls on the room air conditioner are readily accessible and located within 1.8 m (6 ft) of the floor, or (2) an approved manually operable disconnecting means is installed in a readily accessible location within sight from the room air conditioner. [440.63](https://2023.antflix.net#440.63) | https://2023.antflix.net#440.63 |
Chapter 4 Equipment for General Use | 440.64 | Where a flexible cord is used to supply a room air conditioner, the length of such cord shall not exceed 3.0 m (10 ft) for a nominal, 120-volt rating or 1.8 m (6 ft) for a nominal, 208- or 240-volt rating. [440.64](https://2023.antflix.net#440.64) | https://2023.antflix.net#440.64 |
Chapter 4 Equipment for General Use | 440.65 | Single-phase cord- and plug-connected room air conditioners shall be provided with one of the following factory-installed devices: Leakage-current detector-interrupter (LCDI)Arc-fault circuit interrupter (AFCI)Heat detecting circuit interrupter (HDCI)The protection device shall be an integral part of the attachment plug or be located in the power supply cord within 300 mm (12 in.) of the attachment plug. [440.65](https://2023.antflix.net#440.65) | https://2023.antflix.net#440.65 |
Chapter 4 Equipment for General Use | 445.1 | This article contains installation and other requirements for generators. [445.1](https://2023.antflix.net#445.1) | https://2023.antflix.net#445.1 |
Chapter 4 Equipment for General Use | 445.6 | Stationary generators shall be listed. Exception: One of a kind or custom manufactured generators shall be permitted to be field labeled. Informational Note: See UL 2200, Standard for Stationary Engine Generator Assemblies, for additional information. [445.6](https://2023.antflix.net#445.6) | https://2023.antflix.net#445.6 |
Chapter 4 Equipment for General Use | 445.10 | Generators shall be of a type suitable for the locations in which they are installed. They shall also meet the requirements for motors in 430.14. Informational Note: See NFPA 37-2021, Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines, for information on the location of generators. [445.10](https://2023.antflix.net#445.10) | https://2023.antflix.net#445.10 |
Chapter 4 Equipment for General Use | 445.11 | Each generator shall be provided with an accessible nameplate giving the manufacturer's name, the rated frequency, the number of phases if ac, the rating in kilowatts or kilovolt-amperes, the power factor, the normal volts and amperes corresponding to the rating, and the rated ambient temperature. Nameplates or manufacturer's instructions shall provide the following information for all stationary generators and portable generators rated more than 15 kW:Alternator subtransient, transient, synchronous, and zero sequence reactancesGenerator set power rating category (including but not limited to prime, standby, or continuous)Alternator temperature rise at rated load and insulation system classIndication if the generator is protected against overload by inherent design, an overcurrent protective relay, a circuit breaker, or a fuseAvailable fault current for inverter-based generators, in lieu of the synchronous, subtransient, and transient reactancesMarking shall be provided by the manufacturer to indicate whether or not the generator neutral is bonded to its frame. Where the bonding is modified in the field, additional marking shall be required to indicate whether the neutral is bonded to the frame. [445.11](https://2023.antflix.net#445.11) | https://2023.antflix.net#445.11 |
Chapter 4 Equipment for General Use | 445.12(A) | Constant-voltage generators, except ac generator exciters, shall be protected from overload by inherent design, circuit breakers, fuses, protective relays, or other identified overcurrent protective means suitable for the conditions of use. [445.12(A)](https://2023.antflix.net#445.12(A)) | https://2023.antflix.net#445.12(A) |
Chapter 4 Equipment for General Use | 445.12(B) | Two-wire, dc generators shall be permitted to have overcurrent protection in one conductor only if the overcurrent device is actuated by the entire current generated other than the current in the shunt field. The over-current device shall not open the shunt field. [445.12(B)](https://2023.antflix.net#445.12(B)) | https://2023.antflix.net#445.12(B) |
Chapter 4 Equipment for General Use | 445.12(C) | Generators operating at 65 volts or less and driven by individual motors shall be considered as protected by the overcurrent device protecting the motor if these devices will operate when the generators are delivering not more than 150 percent of their full-load rated current. [445.12(C)](https://2023.antflix.net#445.12(C)) | https://2023.antflix.net#445.12(C) |
Chapter 4 Equipment for General Use | 445.12(D) | Two-wire, dc generators used in conjunction with balancer sets to obtain neutral points for 3-wire systems shall be equipped with overcurrent devices that disconnect the 3-wire system in case of excessive unbalancing of voltages or currents. [445.12(D)](https://2023.antflix.net#445.12(D)) | https://2023.antflix.net#445.12(D) |
Chapter 4 Equipment for General Use | 445.12(E) | Three-wire, dc generators, whether compound or shunt wound, shall be equipped with overcurrent devices, one in each armature lead, and connected so as to be actuated by the entire current from the armature. Such overcurrent devices shall consist either of a double-pole, double-coil circuit breaker or of a 4-pole circuit breaker connected in the main and equalizer leads and tripped by two overcurrent devices, one in each armature lead. Such protective devices shall be interlocked so that no one pole can be opened without simultaneously disconnecting both leads of the armature from the system. Exception to (A) through (E): Where deemed by the authority having jurisdiction that a generator is vital to the operation of an electrical system and the generator should operate to failure to prevent a greater hazard to persons, the overload sensing device(s) shall be permitted to be connected to an annunciator or alarm supervised by authorized personnel instead of interrupting the generator circuit. [445.12(E)](https://2023.antflix.net#445.12(E)) | https://2023.antflix.net#445.12(E) |
Chapter 4 Equipment for General Use | 445.13(A) | The ampacity of the conductors from the generator output terminals to the first distribution device(s) containing overcurrent protection shall not be less than 115 percent of the nameplate current rating of the generator. It shall be permitted to size the neutral conductors in accordance with 220.61. Conductors that must carry ground-fault currents shall not be smaller than required by 250.30(A). Neutral conductors of dc generators that must carry ground-fault currents shall not be smaller than the minimum required size of the largest conductor. Exception: Where the design and operation of the generator prevent overloading, the ampacity of the conductors shall not be less than 100 percent of the nameplate current rating of the generator. [445.13(A)](https://2023.antflix.net#445.13(A)) | https://2023.antflix.net#445.13(A) |
Chapter 4 Equipment for General Use | 445.13(B) | Where the generator set is equipped with a listed overcurrent protective device or a combination of a current transformer and overcurrent relay, conductors shall be permitted to be tapped from the load side of the protected terminals in accordance with 240.21 (B). Tapped conductors shall not be permitted for portable generators rated 15 kW or less where field wiring connection terminals are not accessible. [445.13(B)](https://2023.antflix.net#445.13(B)) | https://2023.antflix.net#445.13(B) |
Chapter 4 Equipment for General Use | 445.14 | Live parts of generators operated at more than 50 volts ac or 60 volts dc to ground shall not be exposed to accidental contact where accessible to unqualified persons. [445.14](https://2023.antflix.net#445.14) | https://2023.antflix.net#445.14 |
Chapter 4 Equipment for General Use | 445.15 | Where necessary for the safety of attendants, the requirements of 430.233 shall apply. [445.15](https://2023.antflix.net#445.15) | https://2023.antflix.net#445.15 |
Chapter 4 Equipment for General Use | 445.16 | Where field-installed wiring passes through an opening in an enclosure, a conduit box, or a barrier, a bushing shall be used to protect the conductors from the edges of an opening having sharp edges. The bushing shall have smooth, well-rounded surfaces where it may be in contact with the conductors. If used where oils, grease, or other contaminants may be present, the bushing shall be made of a material not deleteriously affected. [445.16](https://2023.antflix.net#445.16) | https://2023.antflix.net#445.16 |
Chapter 4 Equipment for General Use | 445.17 | Generator terminal housings shall comply with 430.12. Where a horsepower rating is required to determine the required minimum size of the generator terminal housing, the full-load current of the generator shall be compared with comparable motors in Table 430.247 through Table 430.250. The higher horsepower rating of Table 430.247 and Table 430.250 shall be used whenever the generator selection is between two ratings. Exception: This section shall not apply to generators rated over 600 volts. [445.17](https://2023.antflix.net#445.17) | https://2023.antflix.net#445.17 |
Chapter 4 Equipment for General Use | 445.18(A) | Generators other than cord-and-plug-connected portable generators shall have one or more disconnecting means. Each disconnecting means shall simultaneously open all associated ungrounded conductors. Each disconnecting means shall be lockable open in accordance with 110.25. The disconnecting means shall be permitted to be located within the generator behind a hinged cover, door, or enclosure panel. Where the generator disconnecting means is located within the generator, a field applied label meeting the requirements of 110.21(B) shall be provided indicating the location of the generator disconnecting means. [445.18(A)](https://2023.antflix.net#445.18(A)) | https://2023.antflix.net#445.18(A) |
Chapter 4 Equipment for General Use | 445.18(B) | Where a generator is installed in parallel with other generators, the provisions of 445.18(A) shall be capable of isolating the generator output terminals from the paralleling system bus. The disconnecting means shall not be required to be located at the generator. [445.18(B)](https://2023.antflix.net#445.18(B)) | https://2023.antflix.net#445.18(B) |
Chapter 4 Equipment for General Use | 445.19(A) | Generators shall have provisions to shut down the prime mover. The means of shutdown shall comply with all of the following: Be equipped with provisions to disable all prime mover start control circuits to render the prime mover incapable of startingInitiate a shutdown mechanism that requires a mechanical resetThe provisions to shut down the prime mover shall be permitted to satisfy the requirements of 445.18(A) where it is capable of being locked in the open position in accordance with 110.25. [445.19(A)](https://2023.antflix.net#445.19(A)) | https://2023.antflix.net#445.19(A) |
Chapter 4 Equipment for General Use | 445.19(B) | For other than one- and two-family dwelling units, generators with greater than 15 kW rating shall be provided with a remote emergency stop switch to shut down the prime mover. The remote emergency stop switch shall be located outside the equipment room or generator enclosure at a readily accessible location and shall also meet the requirements of 445.19(A)(1) and (A)(2). The remote emergency stop switch shall be permitted to be mounted on the exterior of the generator enclosure. The remote emergency stop switch shall be labeled Generator Emergency Shutdown, and the label shall meet the requirements of 110.21 (B). [445.19(B)](https://2023.antflix.net#445.19(B)) | https://2023.antflix.net#445.19(B) |
Chapter 4 Equipment for General Use | 445.19(C) | For other than cord-and-plug-connected portable generators, an emergency shutdown device shall be located outside the dwelling unit at a readily accessible location and shall also meet the requirements of 445.19(A)(1) and (A)(2). An emergency shutdown device mounted on the exterior of the generator enclosure shall be permitted to satisfy the requirements of this section. The shutdown device shall be marked as the Generator Emergency Shutdown, and the label shall meet the requirements of 110.21 (B)). [445.19(C)](https://2023.antflix.net#445.19(C)) | https://2023.antflix.net#445.19(C) |
Chapter 4 Equipment for General Use | 445.20 | Receptacle outlets that are a part of a 15-kW or smaller portable generator shall have listed ground-fault circuit-interrupter protection (GFCI) for personnel integral to the generator or receptacle as indicated in either 445.20(A) or (B): [445.20](https://2023.antflix.net#445.20) | https://2023.antflix.net#445.20 |
Chapter 4 Equipment for General Use | 445.20(A) | Unbonded generators with both 125-volt and 125/250-volt receptacle outlets shall have listed GFCI protection for personnel integral to the generator or receptacle on all 125-volt, 15- and 20-ampere receptacle outlets. Exception: GFCI protection shall not be required where the 125-volt receptacle outlets(s) is interlocked such that it is not available for use when any 125/250-volt receptacle(s) is in use. [445.20(A)](https://2023.antflix.net#445.20(A)) | https://2023.antflix.net#445.20(A) |
Chapter 4 Equipment for General Use | 445.20(B) | Bonded generators shall be provided with GFCI protection on all 125-volt. 15- and 20-ampere receptacle outlets. Informational Note: See 590.6(A)(3) for GFCI requirements for 15-kW or smaller portable generators used for temporary electric power and lighting. Exception to (A) and (B): If the generator was manufactured or remanufactured prior to January 1, 2015, listed cord sets or devices incorporating listed GFCI protection for personnel identified for portable use shall be permitted. [445.20(B)](https://2023.antflix.net#445.20(B)) | https://2023.antflix.net#445.20(B) |
Chapter 4 Equipment for General Use | 450.1 | This article covers the installation of all transformers other than the following: Current transformersDry-type transformers that constitute a component part of other apparatus and comply with the requirements for such apparatusTransformers that are an integral part of an X-ray, high-frequency, or electrostatic-coating apparatusTransformers used with Class 2 and Class 3 circuitsTransformers for sign and outline lightingTransformers for electric-discharge lightingTransformers used for power-limited fire alarm circuitsTransformers used for research, development, or testing, where effective arrangements are provided to safeguard persons from contacting energized parts [450.1](https://2023.antflix.net#450.1) | https://2023.antflix.net#450.1 |
Chapter 4 Equipment for General Use | 450.2 | Transformers shall individually comply with the requirements of this article unless specific provisions allow for interconnection and operation as a single unit. [450.2](https://2023.antflix.net#450.2) | https://2023.antflix.net#450.2 |
Chapter 4 Equipment for General Use | 450.3 | Overcurrent protection of transformers shall comply with 450.3(A), (B), or (C). As used in this section, the word transformer shall mean a transformer or polyphase bank of two or more single-phase transformers operating as a unit. Informational Note No. 1: See 240.4, 240.21, 245.26, and 245.27 for overcurrent protection of conductors. Informational Note No. 2: Nonlinear loads can increase heat in a transformer without operating its overcurrent protective device. See IEEE 3002.8, Recommended Practice for Conducting Harmonic Studies and Analysis of Industrial and Commercial Power Systems, for additional information. [450.3](https://2023.antflix.net#450.3) | https://2023.antflix.net#450.3 |
Chapter 4 Equipment for General Use | 450.3(A) | Overcurrent protection shall be provided in accordance with Table 450.3(A).Table 450.3(A) Maximum Rating or Setting of Overcurrent Protection for Transformers Over 1000 Volts (as a Percentage of Transformer-Rated Current)
Location Limitations
Transformer Rated Impedance
Primary Protection over 1000 Volts
Secondary Protection2
Over 1000 Volts
1000 Volts or Less
Circuit Breaker4
Fuse Rating
Circuit Breaker4
Fuse Rating
Circuit Breaker or Fuse Rating
Any location
Not more than 6%
600%1
300%1
300%1
250%1
125%1
More than 6% and not more than 10%
400%1
300%1
250%1
225%1
125%1
Supervised locations only3
Any
300%1
250%1
Not required
Not required
Not required
Not more than 6%
600%
300%
300%5
250%5
250%5
More than 6% and not more than 10%
400%
300%
250%5
225%5
250%5
1Where the required fuse rating or circuit breaker setting does not correspond to a standard rating or setting, a higher rating or setting that does not exceed the following shall be permitted:
The next higher standard rating or setting for fuses and circuit breakers 1000 volts and below, or
The next higher commercially available rating or setting for fuses and circuit breakers above 1000 volts.
2Where secondary overcurrent protection is required, the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location. Where multiple overcurrent devices are utilized, the total of all the device ratings shall not exceed the allowed value of a single overcurrent device. If both circuit breakers and fuses are used as the overcurrent device, the total of the device ratings shall not exceed that allowed for fuses.
3A supervised location is a location where conditions of maintenance and supervision ensure that only qualified persons monitor and service the transformer installation.
4Electronically actuated fuses that may be set to open at a specific current shall be set in accordance with settings for circuit breakers.
5A transformer equipped with a coordinated thermal overload protection by the manufacturer shall be permitted to have separate secondary protection omitted. [450.3(A)](https://2023.antflix.net#450.3(A)) | https://2023.antflix.net#450.3(A) |
Chapter 4 Equipment for General Use | 450.3(B) | Overcurrent protection shall be provided in accordance with Table 450.3(B) unless the transformer is installed as a motor control circuit transformer in accordance with 430.72(C)(1) through (C)(5).Table 450.3(B) Maximum Rating or Setting of Overcurrent Protection for Transformers 1000 Volts and Less (as a Percentage of Transformer-Rated Current)
Protection Method
Primary Protection
Secondary Protection2
Currents of 9 Amperes or More
Currents Less Than 9 Amperes
Currents Less Than 2 Amperes
Currents of 9 Amperes or More
Currents Less Than 9 Amperes
Primary only protection
125%1
167%
300%
Not required
Not required
Primary and secondary protection
250%3
250%3
250%3
125%1
167%
1Where 125 percent of this current does not correspond to a standard rating of a fuse or nonadjustable circuit breaker, a higher rating that does not exceed the next higher standard rating shall be permitted.
2Where secondary overcurrent protection is required, the secondary overcurrent device shall be permitted to consist of not more than six circuit breakers or six sets of fuses grouped in one location. Where multiple overcurrent devices are utilized, the total of all the device ratings shall not exceed the allowed value of a single overcurrent device.
3A transformer equipped with coordinated thermal overload protection by the manufacturer and arranged to interrupt the primary current shall be permitted to have primary overcurrent protection rated or set at a current value that is not more than six times the rated current of the transformer for transformers having not more than 6 percent impedance and not more than four times the rated current of the transformer for transformers having more than 6 percent but not more than 10 percent impedance. [450.3(B)](https://2023.antflix.net#450.3(B)) | https://2023.antflix.net#450.3(B) |
Chapter 4 Equipment for General Use | 450.3(C) | Voltage (potential) transformers installed indoors or enclosed shall be protected with primary fuses.
Informational Note: See 408.52 for protection of instrument circuits, including voltage transformers. [450.3(C)](https://2023.antflix.net#450.3(C)) | https://2023.antflix.net#450.3(C) |
Chapter 4 Equipment for General Use | 450.4(A) | Each autotransformer 1000 volts, nominal, or less shall be protected by an individual overcurrent device installed in series with each ungrounded input conductor. Such overcurrent device shall be rated or set at not more than 125 percent of the rated full-load input current of the autotransformer. Where this calculation does not correspond to a standard rating of a fuse or nonadjustable circuit breaker and the rated input current is 9 amperes or more, the next higher standard rating described in 240.6 shall be permitted. An overcurrent device shall not be installed in series with the shunt winding (the winding common to both the input and the output circuits) of the autotransformer between Points A and B as shown in Figure 450.4(A). Exception: Where the rated input current of the autotransformer is less than 9 amperes, an overcurrent device rated or set at not more than 167 percent of the input current shall be permitted.
FIGURE 450.4(A) Autotransformer. [450.4(A)](https://2023.antflix.net#450.4(A)) | https://2023.antflix.net#450.4(A) |
Chapter 4 Equipment for General Use | 450.4(B) | A transformer field-connected as an autotransformer shall be identified for use at elevated voltage. Informational Note: See 210.9 and 215.11 for information on permitted uses of autotransformers. [450.4(B)](https://2023.antflix.net#450.4(B)) | https://2023.antflix.net#450.4(B) |
Chapter 4 Equipment for General Use | 450.5 | Grounding autotransformers covered in this section are zigzag or T-connected transformers connected to 3-phase, 3-wire ungrounded systems for the purpose of creating a 3-phase, 4-wire distribution system or providing a neutral point for grounding purposes. Such transformers shall have a continuous per-phase current rating and a continuous neutral current rating. Zigzag-connected transformers shall not be installed on the load side of any system grounding connection, including those made in accordance with 250.24(C), 250.30(A)(1), or 250.32(B), Exception No. 1. Informational Note: The phase current in a grounding auto-transformer is one-third the neutral current. [450.5](https://2023.antflix.net#450.5) | https://2023.antflix.net#450.5 |
Chapter 4 Equipment for General Use | 450.5(A) | A grounding autotransformer used to create a 3-phase, 4-wire distribution system from a 3-phase, 3-wire ungrounded system shall conform to 450.5(A)(1) through (A)(4). [450.5(A)](https://2023.antflix.net#450.5(A)) | https://2023.antflix.net#450.5(A) |
Chapter 4 Equipment for General Use | 450.5(A)(1) | The transformer shall be directly connected to the ungrounded phase conductors and shall not be switched or provided with overcurrent protection that is independent of the main switch and common-trip overcurrent protection for the 3-phase, 4-wire system. [450.5(A)(1)](https://2023.antflix.net#450.5(A)(1)) | https://2023.antflix.net#450.5(A)(1) |
Chapter 4 Equipment for General Use | 450.5(A)(2) | An overcurrent sensing device shall be provided that will cause the main switch or common-trip overcurrent protection referred to in 450.5(A)(1) to open if the load on the autotransformer reaches or exceeds 125 percent of its continuous current per-phase or neutral rating. Delayed tripping for temporary overcurrents sensed at the autotransformer overcurrent device shall be permitted for the purpose of allowing proper operation of branch or feeder protective devices on the 4-wire system. [450.5(A)(2)](https://2023.antflix.net#450.5(A)(2)) | https://2023.antflix.net#450.5(A)(2) |
Chapter 4 Equipment for General Use | 450.5(A)(3) | A fault-sensing system that causes the opening of a main switch or common-trip overcurrent device for the 3-phase, 4-wire system shall be provided to guard against single-phasing or internal faults. Informational Note: This can be accomplished by the use of two subtractive-connected donut-type current transformers installed to sense and signal when an unbalance occurs in the line current to the autotransformer of 50 percent or more of rated current. [450.5(A)(3)](https://2023.antflix.net#450.5(A)(3)) | https://2023.antflix.net#450.5(A)(3) |
Chapter 4 Equipment for General Use | 450.5(A)(4) | The autotransformer shall have a continuous neutral-current rating that is not less than the maximum possible neutral unbalanced load current of the 4-wire system. [450.5(A)(4)](https://2023.antflix.net#450.5(A)(4)) | https://2023.antflix.net#450.5(A)(4) |
Chapter 4 Equipment for General Use | 450.5(B) | A grounding autotransformer used to make available a specified magnitude of ground-fault current for operation of a ground-responsive protective device on a 3-phase, 3-wire ungrounded system shall conform to 450.5(B)(1) and (B)(2). [450.5(B)](https://2023.antflix.net#450.5(B)) | https://2023.antflix.net#450.5(B) |
Chapter 4 Equipment for General Use | 450.5(B)(1) | The autotransformer shall have a continuous neutral-current rating not less than the specified ground-fault current. [450.5(B)(1)](https://2023.antflix.net#450.5(B)(1)) | https://2023.antflix.net#450.5(B)(1) |
Chapter 4 Equipment for General Use | 450.5(B)(2) | Overcurrent protection shall comply with 450.5(B)(2) (a) and (B)(2) (b). Operation and Interrupting Rating. An overcurrent protective device having an interrupting rating in compliance with 110.9 and that will open simultaneously all ungrounded conductors when it operates shall be applied in the grounding autotransformer branch circuit.Ampere Rating. The overcurrent protection shall be rated or set at a current not exceeding 125 percent of the auto-transformer continuous per-phase current rating or 42 percent of the continuous-current rating of any series-connected devices in the autotransformer neutral connection. Delayed tripping for temporary overcurrents to permit the proper operation of ground-responsive tripping devices on the main system shall be permitted but shall not exceed values that would be more than the short-time current rating of the grounding autotransformer or any series connected devices in the neutral connection thereto.Exception: For high-impedance grounded systems covered in 250.36, where the maximum ground-fault current is designed to be not more than 10 amperes, and where the grounding autotransformer and the grounding impedance are rated for continuous duty, an overcurrent device rated not more than 20 amperes that will simultaneously open all ungrounded conductors shall be permitted to be installed on the line side of the grounding autotransformer. [450.5(B)(2)](https://2023.antflix.net#450.5(B)(2)) | https://2023.antflix.net#450.5(B)(2) |
Chapter 4 Equipment for General Use | 450.5(C) | A grounding autotransformer used to limit transitory overvoltages shall be of suitable rating and connected in accordance with 450.5(A)(1). [450.5(C)](https://2023.antflix.net#450.5(C)) | https://2023.antflix.net#450.5(C) |
Chapter 4 Equipment for General Use | 450.6 | As used in this article, a secondary tie is a circuit operating at 1000 volts, nominal, or less between phases that connects two power sources or power supply points, such as the secondaries of two transformers. The tie shall be permitted to consist of one or more conductors per phase or neutral. Conductors connecting the secondaries of transformers in accordance with 450.7 shall not be considered secondary ties. As used in this section, the word transformer means a transformer or a bank of transformers operating as a unit. [450.6](https://2023.antflix.net#450.6) | https://2023.antflix.net#450.6 |
Chapter 4 Equipment for General Use | 450.6(A) | Tie circuits shall be provided with overcurrent protection at each end as required in Parts I, II, and VIII of Article 240. Under the conditions described in 450.6(A)(1) and 450.6(A)(2), the overcurrent protection shall be permitted to be in accordance with 450.6(A)(3). [450.6(A)](https://2023.antflix.net#450.6(A)) | https://2023.antflix.net#450.6(A) |
Chapter 4 Equipment for General Use | 450.6(A)(1) | Where all loads are connected at the transformer supply points at each end of the tie and overcurrent protection is not provided in accordance with Parts I, II, and VIII of Article 240, the ampacity of the tie shall not be less than 67 percent of the rated secondary current of the highest rated transformer supplying the secondary tie system. [450.6(A)(1)](https://2023.antflix.net#450.6(A)(1)) | https://2023.antflix.net#450.6(A)(1) |
Chapter 4 Equipment for General Use | 450.6(A)(2) | Where load is connected to the tie at any point between transformer supply points and overcurrent protection is not provided in accordance with Parts I, II, and VIII of Article 240, the ampacity of the tie shall not be less than 100 percent of the rated secondary current of the highest rated transformer supplying the secondary tie system. Exception: Tie circuits comprised of multiple conductors per phase shall be permitted to be sized and protected in accordance with 450.6(A)(4). [450.6(A)(2)](https://2023.antflix.net#450.6(A)(2)) | https://2023.antflix.net#450.6(A)(2) |
Chapter 4 Equipment for General Use | 450.6(A)(3) | Under the conditions described in 450.6(A)(1) and (A)(2), both supply ends of each ungrounded tie conductor shall be equipped with a protective device that opens at a predetermined temperature of the tie conductor under short-circuit conditions. This protection shall consist of one of the following: (1) a fusible link cable connector, terminal, or lug, commonly known as a limiter, each being of a size corresponding with that of the conductor and of construction and characteristics according to the operating voltage and the type of insulation on the tie conductors or (2) automatic circuit breakers actuated by devices having comparable time-current characteristics. [450.6(A)(3)](https://2023.antflix.net#450.6(A)(3)) | https://2023.antflix.net#450.6(A)(3) |
Chapter 4 Equipment for General Use | 450.6(A)(4) | Where the tie consists of more than one conductor per phase or neutral, the conductors of each phase or neutral shall comply with 450.6(A)(4) (a) or (A)(4) (b). Interconnected. The conductors shall be interconnected in order to establish a load supply point, and the protective device specified in 450.6(A)(3) shall be provided in each ungrounded tie conductor at this point on both sides of the interconnection. The means of interconnection shall have an ampacity not less than the load to be served.Not Interconnected. The loads shall be connected to one or more individual conductors of a paralleled conductor tie without interconnecting the conductors of each phase or neutral and without the protection specified in 450.6(A)(3) at load connection points. Where this is done, the tie conductors of each phase or neutral shall have a combined capacity ampacity of not less than 133 percent of the rated secondary current of the highest rated transformer supplying the secondary tie system, the total load of such taps shall not exceed the rated secondary current of the highest rated transformer, and the loads shall be equally divided on each phase and on the individual conductors of each phase as far as practicable. [450.6(A)(4)](https://2023.antflix.net#450.6(A)(4)) | https://2023.antflix.net#450.6(A)(4) |
Chapter 4 Equipment for General Use | 450.6(A)(5) | Where the operating voltage exceeds 150 volts to ground, secondary ties provided with limiters shall have a switch at each end that, when open, de-energizes the associated tie conductors and limiters. The current rating of the switch shall not be less than the rated current ampacity of the conductors connected to the switch. It shall be capable of interrupting its rated current, and it shall be constructed so that it will not open under the magnetic forces resulting from short-circuit current. [450.6(A)(5)](https://2023.antflix.net#450.6(A)(5)) | https://2023.antflix.net#450.6(A)(5) |
Chapter 4 Equipment for General Use | 450.6(B) | Where secondary ties are used, an overcurrent device rated or set at not more than 250 percent of the rated secondary current of the transformers shall be provided in the secondary connections of each transformer supplying the tie system. In addition, an automatic circuit breaker actuated by a reverse-current relay set to open the circuit at not more than the rated secondary current of the transformer shall be provided in the secondary connection of each transformer. [450.6(B)](https://2023.antflix.net#450.6(B)) | https://2023.antflix.net#450.6(B) |
Chapter 4 Equipment for General Use | 450.6(C) | Where the secondary tie system is grounded, each transformer secondary supplying the tie system shall be grounded in accordance with 250.30 for separately derived systems. [450.6(C)](https://2023.antflix.net#450.6(C)) | https://2023.antflix.net#450.6(C) |
Chapter 4 Equipment for General Use | 450.7 | Transformers shall be permitted to be operated in parallel and switched as a unit, provided the overcurrent protection for each transformer meets the requirements of 450.3(A) for primary and secondary protective devices over 1000 volts, or 450.3(B) for primary and secondary protective devices 1000 volts or less. [450.7](https://2023.antflix.net#450.7) | https://2023.antflix.net#450.7 |
Chapter 4 Equipment for General Use | 450.8 | Transformers shall be guarded as specified in 450.8(A) through (D). [450.8](https://2023.antflix.net#450.8) | https://2023.antflix.net#450.8 |
Chapter 4 Equipment for General Use | 450.8(A) | Appropriate provisions shall be made to minimize the possibility of damage to transformers from external causes where the transformers are exposed to physical damage. [450.8(A)](https://2023.antflix.net#450.8(A)) | https://2023.antflix.net#450.8(A) |
Chapter 4 Equipment for General Use | 450.8(B) | Dry-type transformers shall be provided with a noncombustible moisture-resistant case or enclosure that provides protection against the accidental insertion of foreign objects. [450.8(B)](https://2023.antflix.net#450.8(B)) | https://2023.antflix.net#450.8(B) |
Chapter 4 Equipment for General Use | 450.8(C) | Switches or other equipment operating at 1000 volts, nominal, or less and serving only equipment within a transformer enclosure shall be permitted to be installed in the transformer enclosure if accessible to qualified persons only. All energized parts shall be guarded in accordance with 110.27 and 110.34. [450.8(C)](https://2023.antflix.net#450.8(C)) | https://2023.antflix.net#450.8(C) |
Chapter 4 Equipment for General Use | 450.8(D) | The operating voltage of exposed live parts of transformer installations shall be indicated by signs or visible markings on the equipment or structures. [450.8(D)](https://2023.antflix.net#450.8(D)) | https://2023.antflix.net#450.8(D) |
Chapter 4 Equipment for General Use | 450.9 | The ventilation shall dispose of the transformer full-load heat losses without creating a temperature rise that is in excess of the transformer rating. Informational Note No. 1: See IEEE C57.12.00-2015, General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers, and IEEE C57.12.01-2020, General Requirements for Dry-Type Distribution and Power Transformers, for additional information. Informational Note No. 2: See IEEE C57.110-2018, Recommended Practice for Establishing Liquid-Filled and Dry-Type Power and Distribution Transformer Capability When Supplying Nonsinusoidal Load Currents, for more information where transformers are used with nonlinear loads that have nonsinusoidal currents that can result in additional losses and transformer heating. Transformers with ventilating openings shall be installed so that the ventilating openings are not blocked by walls or other obstructions. The required clearances shall be clearly marked on the transformer. Transformer top surfaces that are horizontal and readily accessible shall be marked to prohibit storage. [450.9](https://2023.antflix.net#450.9) | https://2023.antflix.net#450.9 |
Chapter 4 Equipment for General Use | 450.10(A) | Where separate equipment grounding conductors and supply-side bonding jumpers are installed, a terminal bar for all grounding and bonding conductor connections shall be secured inside the transformer enclosure. The terminal bar shall be bonded to the enclosure in accordance with 250.12 and shall not be installed on or over any vented portion of the enclosure. Exception: Where a dry-type transformer is equipped with wire-type connections (leads), the grounding and bonding connections shall be permitted to be connected together using any of the methods in 250.8 and shall be bonded to the enclosure if of metal. [450.10(A)](https://2023.antflix.net#450.10(A)) | https://2023.antflix.net#450.10(A) |
Chapter 4 Equipment for General Use | 450.10(B) | Exposed non-current-carrying metal parts of transformer installations, including fences, guards, and so forth, shall be grounded and bonded under the conditions and in the manner specified for electrical equipment and other exposed metal parts in Parts V, VI, and VII of Article 250. [450.10(B)](https://2023.antflix.net#450.10(B)) | https://2023.antflix.net#450.10(B) |
Chapter 4 Equipment for General Use | 450.11(A) | Each transformer shall be provided with a name-plate giving the following information: Name of manufacturerRated kilovolt-amperesFrequencyPrimary and secondary voltageImpedance of transformers 25 kVA and largerRequired clearances for transformers with ventilating openingsAmount and kind of insulating liquid where usedFor dry-type transformers, temperature class for the insulation system [450.11(A)](https://2023.antflix.net#450.11(A)) | https://2023.antflix.net#450.11(A) |
Chapter 4 Equipment for General Use | 450.11(B) | A transformer shall be permitted to be supplied at the marked secondary voltage, provided that the installation is in accordance with the manufacturer's instructions. [450.11(B)](https://2023.antflix.net#450.11(B)) | https://2023.antflix.net#450.11(B) |
Chapter 4 Equipment for General Use | 450.12 | The minimum wire-bending space at fixed, 1000-volt and below terminals of transformer line and load connections shall be as required in 312.6. Wiring space for pigtail connections shall conform to Table 314.16(B)(1). [450.12](https://2023.antflix.net#450.12) | https://2023.antflix.net#450.12 |
Chapter 4 Equipment for General Use | 450.13 | All transformers and transformer vaults shall be readily accessible to qualified personnel for inspection and maintenance or shall meet the requirements of 450.13(A) or 450.13(B). [450.13](https://2023.antflix.net#450.13) | https://2023.antflix.net#450.13 |
Chapter 4 Equipment for General Use | 450.13(A) | Dry-type transformers 1000 volts, nominal, or less, located in the open on walls, columns, or structures, shall not be required to be readily accessible. [450.13(A)](https://2023.antflix.net#450.13(A)) | https://2023.antflix.net#450.13(A) |
Chapter 4 Equipment for General Use | 450.13(B) | Dry-type transformers 1000 volts, nominal, or less and not exceeding 50 kVA shall be permitted in hollow spaces of buildings not permanently closed in by structure, provided they meet the ventilation requirements of 450.9 and separation from combustible materials requirements of 450.21(A). Transformers so installed shall not be required to be readily accessible. [450.13(B)](https://2023.antflix.net#450.13(B)) | https://2023.antflix.net#450.13(B) |
Chapter 4 Equipment for General Use | 450.14 | Transformers, other than Class 2 or Class 3 transformers, shall have a disconnecting means located either in sight of the transformer or in a remote location. Where located in a remote location, the disconnecting means shall be lockable open in accordance with 110.25, and its location shall be field marked on the transformer. [450.14](https://2023.antflix.net#450.14) | https://2023.antflix.net#450.14 |
Chapter 4 Equipment for General Use | 450.21(A) | Dry-type transformers installed indoors and rated 1121/2 kVA or less shall have a separation of at least 300 mm (12 in.) from combustible material unless separated from the combustible material by a fire-resistant, heat-insulated barrier. Exception: This rule shall not apply to transformers rated for 1000 volts, nominal, or less that are completely enclosed, except for ventilating openings. [450.21(A)](https://2023.antflix.net#450.21(A)) | https://2023.antflix.net#450.21(A) |
Chapter 4 Equipment for General Use | 450.21(B) | Individual dry-type transformers of more than 1121/2 kVA rating shall be installed in a transformer room of fire-resistant construction having a minimum fire rating of 1 hour. Exception No. 1: Transformers with Class 155 or higher insulation systems and separated from combustible material by a fire-resistant, heat-insulating barrier or by not less than 1.83 m (6 ft) horizontally and 3.7 m (12 ft) vertically shall not be required to be installed in a transformer room. Exception No. 2: Transformers with Class 155 or higher insulation systems and completely enclosed except for ventilating openings shall not be required to be installed in a transformer room. Informational Note: See ASTM E119-18a, Standard Test Methods for Fire Tests of Building Construction and Materials, for additional information on fire-resistance ratings. [450.21(B)](https://2023.antflix.net#450.21(B)) | https://2023.antflix.net#450.21(B) |
Chapter 4 Equipment for General Use | 450.21(C) | Dry-type transformers rated over 35,000 volts shall be installed in a vault complying with Part III of this article. [450.21(C)](https://2023.antflix.net#450.21(C)) | https://2023.antflix.net#450.21(C) |
Chapter 4 Equipment for General Use | 450.22 | Dry-type transformers installed outdoors shall have a weatherproof enclosure. Transformers exceeding 1121/2 kVA shall not be located within 300 mm (12 in.) of combustible materials of buildings unless the transformer has Class 155 insulation systems or higher and is completely enclosed except for ventilating openings. [450.22](https://2023.antflix.net#450.22) | https://2023.antflix.net#450.22 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.