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Chapter 4 Equipment for General Use | 450.23 | Transformers insulated with listed less-flammable liquids that have a fire point of not less than 300°C shall be permitted to be installed in accordance with 450.23(A) or 450.23(B). [450.23](https://2023.antflix.net#450.23) | https://2023.antflix.net#450.23 |
Chapter 4 Equipment for General Use | 450.23(A) | Indoor installations shall be permitted in accordance with one of the following: In Type I or Type II buildings, in areas where all of the following requirements are met:The transformer is rated 35,000 volts or less.No combustible materials are stored.A liquid confinement area is provided.The installation complies with all the restrictions provided for in the listing of the liquid.Informational Note: Such restrictions can include, but are not limited to, maximum pressure of the tank, use of a pressure relief valve, appropriate fuse types, and proper sizing of overcurrent protection.If an automatic fire extinguishing system and a liquid confinement area is present, provided the transformer is rated 35,000 volts or lessIf the installation complies with 450.26 [450.23(A)](https://2023.antflix.net#450.23(A)) | https://2023.antflix.net#450.23(A) |
Chapter 4 Equipment for General Use | 450.23(B) | Less-flammable liquid-filled transformers shall be permitted to be installed outdoors, attached to, adjacent to, or on the roof of buildings, if installed in accordance with either of the following: For Type I and Type II buildings, the installation shall comply with all the restrictions provided for in the listing of the liquid.Informational Note No. 1: See NFPA 220-2021, Standard on Types of Building Construction, for definitions of Type I and Type II building construction.Informational Note No. 2: Such restrictions can include, but are not limited to, maximum pressure of the tank, use of a pressure relief valve, appropriate fuse types, and proper sizing of overcurrent protection.In accordance with 450.27.Informational Note No. 3: See 450.27 for examples of additional safeguards that can be required for installations adjacent to combustible material, fire escapes, or door and window openings. [450.23(B)](https://2023.antflix.net#450.23(B)) | https://2023.antflix.net#450.23(B) |
Chapter 4 Equipment for General Use | 450.24 | Transformers insulated with a dielectric fluid identified as nonflammable shall be permitted to be installed indoors or outdoors. Such transformers installed indoors and rated over 35,000 volts shall be installed in a vault. Such transformers installed indoors shall be furnished with a liquid confinement area and a pressure-relief vent. The transformers shall be furnished with a means for absorbing any gases generated by arcing inside the tank, or the pressure-relief vent shall be connected to a chimney or flue that will carry such gases to an environmentally safe area. Informational Note: Safety may be increased if fire hazard analyses are performed for such transformer installations. For the purposes of this section, a nonflammable dielectric fluid is one that does not have a flash point or fire point and is not flammable in air. [450.24](https://2023.antflix.net#450.24) | https://2023.antflix.net#450.24 |
Chapter 4 Equipment for General Use | 450.25 | Askarel-insulated transformers installed indoors and rated over 25 kVA shall be furnished with a pressure-relief vent. Where installed in a poorly ventilated place, they shall be furnished with a means for absorbing any gases generated by arcing inside the case, or the pressure-relief vent shall be connected to a chimney or flue that carries such gases outside the building. Askarel-insulated transformers rated over 35,000 volts shall be installed in a vault. [450.25](https://2023.antflix.net#450.25) | https://2023.antflix.net#450.25 |
Chapter 4 Equipment for General Use | 450.26 | Oil-insulated transformers installed indoors shall be installed in a vault constructed as specified in Part III of this article. Exception No. 1: Where the total capacity does not exceed 1121/2 kVA, the vault specified in Part III of this article shall be permitted to be constructed of reinforced concrete that is not less than 100 mm (4 in.) thick. Exception No. 2: Where the nominal voltage does not exceed 1000, a vault shall not be required if suitable arrangements are made to prevent a transformer oil fire from igniting other materials and the total capacity in one location does not exceed 10 kVA in a section of the building classified as combustible or 75 kVA where the surrounding structure is classified as fire-resistant construction. Exception No. 3: Electric furnace transformers that have a total rating not exceeding 75 kVA shall be permitted to be installed without a vault in a building or room of fire-resistant construction, provided suitable arrangements are made to prevent a transformer oil fire from spreading to other combustible material. Exception No. 4: A transformer that has a total rating not exceeding 75 kVA and a supply voltage of 1000 volts or less that is an integral part of charged-particle-accelerating equipment shall be permitted to be installed without a vault in a building or room of noncombustible or fire-resistant construction, provided suitable arrangements are made to prevent a transformer oil fire from spreading to other combustible material. Exception No. 5: Transformers shall be permitted to be installed in a detached building that does not comply with Part III of this article if neither the building nor its contents present a fire hazard to any other building or property, and if the building is used only in supplying electric service and the interior is accessible only to qualified persons. Exception No. 6: Oil-insulated transformers shall be permitted to be used without a vault in portable and mobile surface mining equipment (such as electric excavators) if each of the following conditions is met: (1) Provision is made for draining leaking fluid to the ground. (2) Safe egress is provided for personnel. (3) A minimum 6-mm (1/4-in.) steel barrier is provided for personnel protection. [450.26](https://2023.antflix.net#450.26) | https://2023.antflix.net#450.26 |
Chapter 4 Equipment for General Use | 450.27 | Combustible material, combustible buildings, and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires originating in oil-insulated transformers installed on roofs, attached to or adjacent to a building or combustible material. In cases where the transformer installation presents a fire hazard, one or more of the following safeguards shall be applied according to the degree of hazard involved:Space separationsFire-resistant barriersAutomatic fire suppression systemsEnclosures that confine the oil of a ruptured transformer tankOil enclosures shall be permitted to consist of fire-resistant dikes, curbed areas or basins, or trenches filled with coarse, crushed stone. Oil enclosures shall be provided with trapped drains where the exposure and the quantity of oil involved are such that removal of oil is important.Informational Note: See ANSI/IEEE C2-2017, National Electrical Safety Code, for additional information on transformers installed on poles or structures or underground. [450.27](https://2023.antflix.net#450.27) | https://2023.antflix.net#450.27 |
Chapter 4 Equipment for General Use | 450.28 | When modifications are made to a transformer in an existing installation that change the type of the transformer with respect to Part II of this article, such transformer shall be marked to show the type of insulating liquid installed, and the modified transformer installation shall comply with the applicable requirements for that type of transformer. [450.28](https://2023.antflix.net#450.28) | https://2023.antflix.net#450.28 |
Chapter 4 Equipment for General Use | 450.41 | Vaults shall be located where they can be ventilated to the outside air without using flues or ducts wherever such an arrangement is practicable. [450.41](https://2023.antflix.net#450.41) | https://2023.antflix.net#450.41 |
Chapter 4 Equipment for General Use | 450.42 | The walls and roofs of vaults shall be constructed of materials that have approved structural strength for the conditions with a minimum fire resistance of 3 hours. The floors of vaults in contact with the earth shall be of concrete that is not less than 100 mm (4 in.) thick, but, where the vault is constructed with a vacant space or other stories below it, the floor shall have approved structural strength for the load imposed thereon and a minimum fire resistance of 3 hours. For the purposes of this section, studs and wallboard construction shall not be permitted. Exception: Where transformers are protected with automatic sprinkler, water spray, carbon dioxide, or halon, construction of 1-hour rating shall be permitted. Informational Note No. 1: See ASTM E119-20, Standard Test Methods for Fire Tests of Building Construction and Materials, for additional information. Informational Note No. 2: A typical 3-hour construction is 150 mm (6 in.) thick reinforced concrete. [450.42](https://2023.antflix.net#450.42) | https://2023.antflix.net#450.42 |
Chapter 4 Equipment for General Use | 450.43 | Vault doorways shall be protected in accordance with 450.43(A), (B), and (C). [450.43](https://2023.antflix.net#450.43) | https://2023.antflix.net#450.43 |
Chapter 4 Equipment for General Use | 450.43(A) | Each doorway leading into a vault from the building interior shall be provided with a tight-fitting door that has a minimum fire rating of 3 hours. The authority having jurisdiction shall be permitted to require such a door for an exterior wall opening where conditions warrant. Exception: Where transformers are protected with automatic sprinkler, water spray, carbon dioxide, or halon, construction of 1-hour rating shall be permitted. Informational Note: See NFPA 80-2019, Standard for Fire Doors and Other Opening Protectives, for additional information. [450.43(A)](https://2023.antflix.net#450.43(A)) | https://2023.antflix.net#450.43(A) |
Chapter 4 Equipment for General Use | 450.43(B) | A door sill or curb that is of an approved height that will confine the oil from the largest transformer within the vault shall be provided, and in no case shall the height be less than 100 mm (4 in.). [450.43(B)](https://2023.antflix.net#450.43(B)) | https://2023.antflix.net#450.43(B) |
Chapter 4 Equipment for General Use | 450.43(C) | Doors shall be equipped with locks, and doors shall be kept locked, with access being allowed only to qualified persons. Personnel doors shall be capable of opening not less than 90 degrees in the direction of egress and be equipped with listed fire exit hardware. [450.43(C)](https://2023.antflix.net#450.43(C)) | https://2023.antflix.net#450.43(C) |
Chapter 4 Equipment for General Use | 450.45 | Where required by 450.9, openings for ventilation shall be provided in accordance with 450.45(A) through (F). [450.45](https://2023.antflix.net#450.45) | https://2023.antflix.net#450.45 |
Chapter 4 Equipment for General Use | 450.45(A) | Ventilation openings shall be located as far as possible from doors, windows, fire escapes, and combustible material. [450.45(A)](https://2023.antflix.net#450.45(A)) | https://2023.antflix.net#450.45(A) |
Chapter 4 Equipment for General Use | 450.45(B) | A vault ventilated by natural circulation of air shall be permitted to have roughly half of the total area of openings required for ventilation in one or more openings near the floor and the remainder in one or more openings in the roof or in the sidewalls near the roof, or all of the area required for ventilation shall be permitted in one or more openings in or near the roof. [450.45(B)](https://2023.antflix.net#450.45(B)) | https://2023.antflix.net#450.45(B) |
Chapter 4 Equipment for General Use | 450.45(C) | For a vault ventilated by natural circulation of air to an outdoor area, the combined net area of all ventilating openings, after deducting the area occupied by screens, gratings, or louvers, shall not be less than 1900 mm2 (3 in.2) per kVA of transformer capacity in service, and in no case shall the net area be less than 0.1 m2 (1 ft2) for any capacity under 50 kVA. [450.45(C)](https://2023.antflix.net#450.45(C)) | https://2023.antflix.net#450.45(C) |
Chapter 4 Equipment for General Use | 450.45(D) | Ventilation openings shall be covered with durable gratings, screens, or louvers, according to the treatment required in order to avoid unsafe conditions. [450.45(D)](https://2023.antflix.net#450.45(D)) | https://2023.antflix.net#450.45(D) |
Chapter 4 Equipment for General Use | 450.45(E) | All ventilation openings to the indoors shall be provided with automatic closing fire dampers that operate in response to a vault fire. Such dampers shall possess a standard fire rating of not less than 11/2 hours. Informational Note: See ANSI/UL 555-2020, Standard for Fire Dampers, for additional information on fire dampers. [450.45(E)](https://2023.antflix.net#450.45(E)) | https://2023.antflix.net#450.45(E) |
Chapter 4 Equipment for General Use | 450.45(F) | Ventilating ducts shall be constructed of fire-resistant material. [450.45(F)](https://2023.antflix.net#450.45(F)) | https://2023.antflix.net#450.45(F) |
Chapter 4 Equipment for General Use | 450.46 | Where practicable, vaults containing more than 100 kVA transformer capacity shall be provided with a drain or other means that will carry off any accumulation of oil or water in the vault unless local conditions make this impracticable. The floor shall be pitched to the drain where provided. [450.46](https://2023.antflix.net#450.46) | https://2023.antflix.net#450.46 |
Chapter 4 Equipment for General Use | 450.47 | Any pipe or duct system foreign to the electrical installation shall not enter or pass through a transformer vault. Piping or other facilities provided for vault fire protection, or for transformer cooling, shall not be considered foreign to the electrical installation. [450.47](https://2023.antflix.net#450.47) | https://2023.antflix.net#450.47 |
Chapter 4 Equipment for General Use | 450.48 | Materials shall not be stored in transformer vaults. [450.48](https://2023.antflix.net#450.48) | https://2023.antflix.net#450.48 |
Chapter 4 Equipment for General Use | 455.1 | This article covers the installation and use of phase converters. [455.1](https://2023.antflix.net#455.1) | https://2023.antflix.net#455.1 |
Chapter 4 Equipment for General Use | 455.3 | Phase converters shall comply with this article and with the applicable provisions of other articles of this Code. [455.3](https://2023.antflix.net#455.3) | https://2023.antflix.net#455.3 |
Chapter 4 Equipment for General Use | 455.4 | Each phase converter shall be provided with a permanent nameplate indicating the following: Manufacturer's nameRated input and output voltagesFrequencyRated single-phase input full-load amperesRated minimum and maximum single load in kilovolt-amperes (kVA) or horsepowerMaximum total load in kilovolt-amperes (kVA) or horsepowerFor a rotary-phase converter, 3-phase amperes at full load [455.4](https://2023.antflix.net#455.4) | https://2023.antflix.net#455.4 |
Chapter 4 Equipment for General Use | 455.5 | A means for attachment of an equipment grounding conductor termination in accordance with 250.8 shall be provided. [455.5](https://2023.antflix.net#455.5) | https://2023.antflix.net#455.5 |
Chapter 4 Equipment for General Use | 455.6(A) | The ampacity of the single-phase supply conductors shall be determined by 455.6(A)(1) or (A)(2). Informational Note: Single-phase conductors sized to prevent a voltage drop not exceeding 3 percent from the source of supply to the phase converter may help ensure proper starting and operation of motor loads. [455.6(A)](https://2023.antflix.net#455.6(A)) | https://2023.antflix.net#455.6(A) |
Chapter 4 Equipment for General Use | 455.6(A)(1) | Where the loads to be supplied are variable, the conductor ampacity shall not be less than 125 percent of the phase converter nameplate single-phase input full-load amperes. [455.6(A)(1)](https://2023.antflix.net#455.6(A)(1)) | https://2023.antflix.net#455.6(A)(1) |
Chapter 4 Equipment for General Use | 455.6(A)(2) | Where the phase converter supplies specific fixed loads, and the conductor ampacity is less than 125 percent of the phase converter nameplate single-phase input full-load amperes, the conductors shall have an ampacity not less than 250 percent of the sum of the full-load, 3-phase current rating of the motors and other loads served where the input and output voltages of the phase converter are identical. Where the input and output voltages of the phase converter are different, the current as determined by this section shall be multiplied by the ratio of output to input voltage. [455.6(A)(2)](https://2023.antflix.net#455.6(A)(2)) | https://2023.antflix.net#455.6(A)(2) |
Chapter 4 Equipment for General Use | 455.6(B) | The manufactured phase conductors shall be identified in all accessible locations with a distinctive marking. The marking shall be consistent throughout the system and premises. [455.6(B)](https://2023.antflix.net#455.6(B)) | https://2023.antflix.net#455.6(B) |
Chapter 4 Equipment for General Use | 455.7 | The single-phase supply conductors and phase converter shall be protected from over-current by 455.7(A) or (B). Where the required fuse or nonadjustable circuit breaker rating or settings of adjustable circuit breakers do not correspond to a standard rating or setting, a higher rating or setting that does not exceed the next higher standard rating shall be permitted. [455.7](https://2023.antflix.net#455.7) | https://2023.antflix.net#455.7 |
Chapter 4 Equipment for General Use | 455.7(A) | Where the loads to be supplied are variable, overcurrent protection shall be set at not more than 125 percent of the phase converter nameplate single-phase input full-load amperes. [455.7(A)](https://2023.antflix.net#455.7(A)) | https://2023.antflix.net#455.7(A) |
Chapter 4 Equipment for General Use | 455.7(B) | Where the phase converter supplies specific fixed loads and the conductors are sized in accordance with 455.6(A)(2), the conductors shall be protected in accordance with their ampacity. The overcurrent protection determined from this section shall not exceed 125 percent of the phase converter nameplate single-phase input amperes. [455.7(B)](https://2023.antflix.net#455.7(B)) | https://2023.antflix.net#455.7(B) |
Chapter 4 Equipment for General Use | 455.8 | Means shall be provided to disconnect simultaneously all ungrounded single-phase supply conductors to the phase converter. [455.8](https://2023.antflix.net#455.8) | https://2023.antflix.net#455.8 |
Chapter 4 Equipment for General Use | 455.8(A) | The disconnecting means shall be readily accessible and located in sight from the phase converter. [455.8(A)](https://2023.antflix.net#455.8(A)) | https://2023.antflix.net#455.8(A) |
Chapter 4 Equipment for General Use | 455.8(B) | The disconnecting means shall be a switch rated in horsepower, a circuit breaker, or a molded-case switch. Where only nonmotor loads are served, an ampere-rated switch shall be permitted. [455.8(B)](https://2023.antflix.net#455.8(B)) | https://2023.antflix.net#455.8(B) |
Chapter 4 Equipment for General Use | 455.8(C) | The ampere rating of the disconnecting means shall not be less than 115 percent of the rated maximum single-phase input full-load amperes or, for specific fixed loads, shall be permitted to be selected from 455.8(C)(1) or (C)(2). [455.8(C)](https://2023.antflix.net#455.8(C)) | https://2023.antflix.net#455.8(C) |
Chapter 4 Equipment for General Use | 455.8(C)(1) | The disconnecting means shall be a circuit breaker or molded-case switch with an ampere rating not less than 250 percent of the sum of the following: Full-load, 3-phase current ratings of the motorsOther loads served [455.8(C)(1)](https://2023.antflix.net#455.8(C)(1)) | https://2023.antflix.net#455.8(C)(1) |
Chapter 4 Equipment for General Use | 455.8(C)(2) | The disconnecting means shall be a switch with a horsepower rating. The equivalent locked rotor current of the horsepower rating of the switch shall not be less than 200 percent of the sum of the following: Nonmotor loadsThe 3-phase, locked-rotor current of the largest motor as determined from Table 430.251 (B)The full-load current of all other 3-phase motors operating at the same time [455.8(C)(2)](https://2023.antflix.net#455.8(C)(2)) | https://2023.antflix.net#455.8(C)(2) |
Chapter 4 Equipment for General Use | 455.8(D) | The calculations in 455.8(C) shall apply directly where the input and output voltages of the phase converter are identical. Where the input and output voltages of the phase converter are different, the current shall be multiplied by the ratio of the output to input voltage. [455.8(D)](https://2023.antflix.net#455.8(D)) | https://2023.antflix.net#455.8(D) |
Chapter 4 Equipment for General Use | 455.9 | Where single-phase loads are connected on the load side of a phase converter, they shall not be connected to the manufactured phase. [455.9](https://2023.antflix.net#455.9) | https://2023.antflix.net#455.9 |
Chapter 4 Equipment for General Use | 455.10 | A terminal housing in accordance with the provisions of 430.12 shall be provided on a phase converter. [455.10](https://2023.antflix.net#455.10) | https://2023.antflix.net#455.10 |
Chapter 4 Equipment for General Use | 455.20 | The single-phase disconnecting means for the input of a static phase converter shall be permitted to serve as the disconnecting means for the phase converter and a single load if the load is within sight of the disconnecting means. [455.20](https://2023.antflix.net#455.20) | https://2023.antflix.net#455.20 |
Chapter 4 Equipment for General Use | 455.21 | Power to the utilization equipment shall not be supplied until the rotary-phase converter has been started. [455.21](https://2023.antflix.net#455.21) | https://2023.antflix.net#455.21 |
Chapter 4 Equipment for General Use | 455.22 | Utilization equipment supplied by a rotary-phase converter shall be controlled in such a manner that power to the equipment will be disconnected in the event of a power interruption. Informational Note: Magnetic motor starters, magnetic contactors, and similar devices, with manual or time delay restarting for the load, provide restarting after power interruption. [455.22](https://2023.antflix.net#455.22) | https://2023.antflix.net#455.22 |
Chapter 4 Equipment for General Use | 455.23 | Capacitors that are not an integral part of the rotary-phase conversion system but are installed for a motor load shall be connected to the line side of that motor overload protective device. [455.23](https://2023.antflix.net#455.23) | https://2023.antflix.net#455.23 |
Chapter 4 Equipment for General Use | 460.1 | This article covers the installation of capacitors on electrical circuits. Surge capacitors or capacitors included as a component part of other apparatus and conforming with the requirements of such apparatus are excluded from these requirements. [460.1](https://2023.antflix.net#460.1) | https://2023.antflix.net#460.1 |
Chapter 4 Equipment for General Use | 460.3(A) | Capacitors containing more than 11 L (3 gal) of flammable liquid shall be enclosed in vaults or outdoor fenced enclosures complying with Article 110, Part III. This limit shall apply to any single unit in an installation of capacitors. [460.3(A)](https://2023.antflix.net#460.3(A)) | https://2023.antflix.net#460.3(A) |
Chapter 4 Equipment for General Use | 460.3(B) | Where capacitors are accessible to unauthorized and unqualified persons, they shall be enclosed, located, or guarded so that persons cannot come into accidental contact or bring conducting materials into accidental contact with exposed energized parts, terminals, or buses associated with them. However, no additional guarding is required for enclosures accessible only to authorized and qualified persons. [460.3(B)](https://2023.antflix.net#460.3(B)) | https://2023.antflix.net#460.3(B) |
Chapter 4 Equipment for General Use | 460.6 | Capacitors shall be provided with a means of discharging stored energy. [460.6](https://2023.antflix.net#460.6) | https://2023.antflix.net#460.6 |
Chapter 4 Equipment for General Use | 460.6(A) | The residual voltage of a capacitor shall be reduced to 50 volts, nominal, or less within 1 minute after the capacitor is disconnected from the source of supply. [460.6(A)](https://2023.antflix.net#460.6(A)) | https://2023.antflix.net#460.6(A) |
Chapter 4 Equipment for General Use | 460.6(B) | The discharge circuit shall be either permanently connected to the terminals of the capacitor or capacitor bank or provided with automatic means of connecting it to the terminals of the capacitor bank on removal of voltage from the line. Manual means of switching or connecting the discharge circuit shall not be used. [460.6(B)](https://2023.antflix.net#460.6(B)) | https://2023.antflix.net#460.6(B) |
Chapter 4 Equipment for General Use | 460.8(A) | The ampacity of capacitor circuit conductors shall not be less than 135 percent of the rated current of the capacitor. The ampacity of conductors that connect a capacitor to the terminals of a motor or to motor circuit conductors shall not be less than one-third the ampacity of the motor circuit conductors and in no case less than 135 percent of the rated current of the capacitor. [460.8(A)](https://2023.antflix.net#460.8(A)) | https://2023.antflix.net#460.8(A) |
Chapter 4 Equipment for General Use | 460.8(B) | An overcurrent device shall be provided in each ungrounded conductor for each capacitor bank. The rating or setting of the overcurrent device shall be as low as practicable. Exception: A separate overcurrent device shall not be required for a capacitor connected on the load side of a motor overload protective device. [460.8(B)](https://2023.antflix.net#460.8(B)) | https://2023.antflix.net#460.8(B) |
Chapter 4 Equipment for General Use | 460.8(C) | A disconnecting means shall be provided in each ungrounded conductor for each capacitor bank and shall meet the following requirements: The disconnecting means shall open all ungrounded conductors simultaneously.The disconnecting means shall be permitted to disconnect the capacitor from the line as a regular operating procedure.The rating of the disconnecting means shall not be less than 135 percent of the rated current of the capacitor.Exception: A separate disconnecting means shall not be required where a capacitor is connected on the load side of a motor controller. [460.8(C)](https://2023.antflix.net#460.8(C)) | https://2023.antflix.net#460.8(C) |
Chapter 4 Equipment for General Use | 460.9 | Where a motor installation includes a capacitor connected on the load side of the motor overload device, the rating or setting of the motor overload device shall be based on the improved power factor of the motor circuit. The effect of the capacitor shall be disregarded in determining the motor circuit conductor rating in accordance with 430.22. [460.9](https://2023.antflix.net#460.9) | https://2023.antflix.net#460.9 |
Chapter 4 Equipment for General Use | 460.10 | Capacitor cases shall be connected to the equipment grounding conductor. Exception: Capacitor cases shall not be connected to the equipment grounding conductor where the capacitor units are supported on a structure designed to operate at other than ground potential. [460.10](https://2023.antflix.net#460.10) | https://2023.antflix.net#460.10 |
Chapter 4 Equipment for General Use | 460.12 | Each capacitor shall be provided with a nameplate giving the name of the manufacturer, rated voltage, frequency, kilovar or amperes, number of phases, and, if filled with a combustible liquid, the volume of liquid. Where filled with a nonflammable liquid, the nameplate shall so state. The nameplate shall also indicate whether a capacitor has a discharge device inside the case. [460.12](https://2023.antflix.net#460.12) | https://2023.antflix.net#460.12 |
Chapter 4 Equipment for General Use | 460.24(A) | Switches shall be rated for switching of capacitive loads. Capacitor switch operation shall open all ungrounded conductors and the switch shall be capable of the following: Carrying continuously not less than 135 percent of the rated current of the capacitor installationInterrupting the maximum continuous load current of each capacitor, capacitor bank, or capacitor installation that will be switched as a unitWithstanding the maximum inrush current, including contributions from adjacent capacitor installationsCarrying currents due to faults on capacitor side of switch [460.24(A)](https://2023.antflix.net#460.24(A)) | https://2023.antflix.net#460.24(A) |
Chapter 4 Equipment for General Use | 460.24(B)(1) | A means shall be installed to isolate from all sources of voltage each capacitor, capacitor bank, or capacitor installation that will be removed from service as a unit. The isolating means shall provide a visible gap in the electrical circuit adequate for the operating voltage. [460.24(B)(1)](https://2023.antflix.net#460.24(B)(1)) | https://2023.antflix.net#460.24(B)(1) |
Chapter 4 Equipment for General Use | 460.24(B)(2) | Isolating or disconnecting switches (with no interrupting rating) shall be interlocked with the load-interrupting device or be provided with prominently displayed caution signs in accordance with 495.22 to prevent switching load current. [460.24(B)(2)](https://2023.antflix.net#460.24(B)(2)) | https://2023.antflix.net#460.24(B)(2) |
Chapter 4 Equipment for General Use | 460.24(C) | The proper switching sequence shall be ensured by use of one of the following: Mechanically sequenced isolating and bypass switchesInterlocksSwitching procedure prominently displayed at the switching location [460.24(C)](https://2023.antflix.net#460.24(C)) | https://2023.antflix.net#460.24(C) |
Chapter 4 Equipment for General Use | 460.25(A) | A means shall be provided to detect and interrupt fault current likely to cause dangerous pressure within an individual capacitor. [460.25(A)](https://2023.antflix.net#460.25(A)) | https://2023.antflix.net#460.25(A) |
Chapter 4 Equipment for General Use | 460.25(B) | Single-pole or multipole devices shall be permitted for this purpose. [460.25(B)](https://2023.antflix.net#460.25(B)) | https://2023.antflix.net#460.25(B) |
Chapter 4 Equipment for General Use | 460.25(C) | Capacitors shall be permitted to be protected individually or in groups. [460.25(C)](https://2023.antflix.net#460.25(C)) | https://2023.antflix.net#460.25(C) |
Chapter 4 Equipment for General Use | 460.25(D) | Protective devices for capacitors or capacitor equipment shall be rated or adjusted to operate within the limits of the safe zone for individual capacitors. [460.25(D)](https://2023.antflix.net#460.25(D)) | https://2023.antflix.net#460.25(D) |
Chapter 4 Equipment for General Use | 460.26 | Each capacitor shall be provided with a permanent nameplate giving the manufacturer's name, rated voltage, frequency, kilovar or amperes, number of phases, and the volume of liquid identified as flammable, if such is the case. [460.26](https://2023.antflix.net#460.26) | https://2023.antflix.net#460.26 |
Chapter 4 Equipment for General Use | 460.27 | Capacitor cases shall be connected to the equipment grounding conductor. If the capacitor neutral point is connected to a grounding electrode conductor, the connection shall be made in accordance with Part III of Article 250. Exception: Capacitor cases shall not be connected to the equipment grounding conductor where the capacitor units are supported on a structure designed to operate at other than ground potential. [460.27](https://2023.antflix.net#460.27) | https://2023.antflix.net#460.27 |
Chapter 4 Equipment for General Use | 460.28(A) | A means shall be provided to reduce the residual voltage of a capacitor to 50 volts or less within 5 minutes after the capacitor is disconnected from the source of supply. [460.28(A)](https://2023.antflix.net#460.28(A)) | https://2023.antflix.net#460.28(A) |
Chapter 4 Equipment for General Use | 460.28(B) | A discharge circuit shall be either permanently connected to the terminals of the capacitor or provided with automatic means of connecting it to the terminals of the capacitor bank after disconnection of the capacitor from the source of supply. The windings of motors, transformers, or other equipment directly connected to capacitors without a switch or overcurrent device interposed shall meet the requirements of 460.28(A). [460.28(B)](https://2023.antflix.net#460.28(B)) | https://2023.antflix.net#460.28(B) |
Chapter 4 Equipment for General Use | 470.1 | This article covers the installation of separate resistors and reactors on electrical circuits. Exception: This article does not cover resistors and reactors that are component parts of other apparatus. [470.1](https://2023.antflix.net#470.1) | https://2023.antflix.net#470.1 |
Chapter 4 Equipment for General Use | 470.2(A) | Reconditioned resistors shall not be permitted. [470.2(A)](https://2023.antflix.net#470.2(A)) | https://2023.antflix.net#470.2(A) |
Chapter 4 Equipment for General Use | 470.2(B) | Reconditioned reactors shall be permitted. [470.2(B)](https://2023.antflix.net#470.2(B)) | https://2023.antflix.net#470.2(B) |
Chapter 4 Equipment for General Use | 470.10 | Resistors and reactors shall not be placed where exposed to physical damage. [470.10](https://2023.antflix.net#470.10) | https://2023.antflix.net#470.10 |
Chapter 4 Equipment for General Use | 470.11 | A thermal barrier shall be required if the space between the resistors or reactors and any combustible material is less than 305 mm (12 in.). [470.11](https://2023.antflix.net#470.11) | https://2023.antflix.net#470.11 |
Chapter 4 Equipment for General Use | 470.12 | Insulated conductors used for connections between resistance elements and controllers shall be suitable for an operating temperature of not less than 90°C (194°F). Exception: Other conductor insulations shall be permitted for the motor starting service. [470.12](https://2023.antflix.net#470.12) | https://2023.antflix.net#470.12 |
Chapter 4 Equipment for General Use | 470.20(A) | Resistors and reactors shall be protected against physical damage. [470.20(A)](https://2023.antflix.net#470.20(A)) | https://2023.antflix.net#470.20(A) |
Chapter 4 Equipment for General Use | 470.20(B) | Resistors and reactors shall be isolated by enclosure or elevation to protect personnel from accidental contact with energized parts. [470.20(B)](https://2023.antflix.net#470.20(B)) | https://2023.antflix.net#470.20(B) |
Chapter 4 Equipment for General Use | 470.20(C) | Resistors and reactors shall not be installed in close enough proximity to combustible materials to constitute a fire hazard and shall have a clearance of not less than 305 mm (12 in.) from combustible materials. [470.20(C)](https://2023.antflix.net#470.20(C)) | https://2023.antflix.net#470.20(C) |
Chapter 4 Equipment for General Use | 470.20(D) | Clearances from resistors and reactors to grounded surfaces shall be adequate for the voltage involved. [470.20(D)](https://2023.antflix.net#470.20(D)) | https://2023.antflix.net#470.20(D) |
Chapter 4 Equipment for General Use | 470.20(E) | Metallic enclosures of reactors and adjacent metal parts shall be installed so that the temperature rise from induced circulating currents is not hazardous to personnel or does not constitute a fire hazard. [470.20(E)](https://2023.antflix.net#470.20(E)) | https://2023.antflix.net#470.20(E) |
Chapter 4 Equipment for General Use | 470.21 | Resistor and reactor cases or enclosures shall be connected to the equipment grounding conductor. Exception: Resistor or reactor cases or enclosures supported on a structure designed to operate at other than ground potential shall not be connected to the equipment grounding conductor. [470.21](https://2023.antflix.net#470.21) | https://2023.antflix.net#470.21 |
Chapter 4 Equipment for General Use | 470.22 | Installation of oil-filled reactors, in addition to the above requirements, shall comply with applicable requirements of Part II and Part III of Article 450. [470.22](https://2023.antflix.net#470.22) | https://2023.antflix.net#470.22 |
Chapter 4 Equipment for General Use | 480.1 | This article applies to all installations of stationary standby batteries having a capacity greater than 3.6 MJ (1 kWh). Informational Note No. 1: See Article 706 for installations that do not meet the definition of stationary standby batteries. Informational Note No. 2: The following standards are frequently referenced for the installation of stationary batteries: IEEE 484, Recommended Practice for Installation Design and Installation of Vented Lead-Acid Batteries for Stationary ApplicationsIEEE 485, Recommended Practice for Sizing Vented Lead-Acid Storage Batteries for Stationary ApplicationsIEEE 1145, Recommended Practice for Installation and Maintenance of Nickel-Cadmium Batteries for Photovoltaic (PV) SystemsIEEE 1187, IEEE Recommended Practice for Installation Design, and Installation of Valve-Regulated Lead-Acid Batteries for Stationary ApplicationsIEEE 1375, IEEE Guide for the Protection of Stationary Battery SystemsIEEE 1578, Recommended Practice for Stationary Battery Electrolyte Spill Containment and ManagementIEEE 1635/ASHRAE 21, Guide for the Ventilation and Thermal Management of Batteries for Stationary ApplicationsUL 1973, Standard for Batteries for Use in Stationary, Vehicle Auxiliary Power, and Light Electric Rail (LER) ApplicationsUL Subject 2436, Outline of Investigation for Spill Containment for Stationary Lead Acid Battery SystemsUL 1989, Standard for Standby BatteriesUL Subject 1974, Standard for Evaluation of Repurposed BatteriesNFPA 855-2020, Standard for the Installation of Stationary Energy Storage Systems [480.1](https://2023.antflix.net#480.1) | https://2023.antflix.net#480.1 |
Chapter 4 Equipment for General Use | 480.3 | Storage batteries and battery management equipment shall be listed. This requirement shall not apply to lead-acid batteries. [480.3](https://2023.antflix.net#480.3) | https://2023.antflix.net#480.3 |
Chapter 4 Equipment for General Use | 480.4(A) | Where mating dissimilar metals, antioxidant material suitable for the battery connection shall be used where recommended by the battery manufacturer's installation and instruction manual. [480.4(A)](https://2023.antflix.net#480.4(A)) | https://2023.antflix.net#480.4(A) |
Chapter 4 Equipment for General Use | 480.4(B) | The ampacity of field-assembled intercell and intertier connectors and conductors shall be of such cross-sectional area that the temperature rise under maximum load conditions and at maximum ambient temperature shall not exceed the safe operating temperature of the conductor insulation or of the material of the conductor supports. Informational Note: Conductors sized to prevent a voltage drop exceeding 3 percent of maximum anticipated load, and where the maximum total voltage drop to the furthest point of connection does not exceed 5 percent, may not be appropriate for all battery applications. IEEE 1375-2003, Guide for the Protection of Stationary Battery Systems, provides guidance for overcurrent protection and associated cable sizing. [480.4(B)](https://2023.antflix.net#480.4(B)) | https://2023.antflix.net#480.4(B) |
Chapter 4 Equipment for General Use | 480.4(C) | Electrical connections to the battery, and the cable(s) between cells on separate levels or racks, shall not put mechanical strain on the battery terminals. Terminal plates shall be used where practicable. Informational Note: Conductors are commonly pre-formed to eliminate stress on battery terminations. Fine stranded cables may also eliminate the stress on battery terminations. See the manufacturer's instructions for guidance. [480.4(C)](https://2023.antflix.net#480.4(C)) | https://2023.antflix.net#480.4(C) |
Chapter 4 Equipment for General Use | 480.4(D) | The terminals of all cells or multicell units shall be readily accessible for readings, inspections, and cleaning where required by the equipment design. One side of transparent battery containers shall be readily accessible for inspection of the internal components. [480.4(D)](https://2023.antflix.net#480.4(D)) | https://2023.antflix.net#480.4(D) |
Chapter 4 Equipment for General Use | 480.5 | Wiring and equipment supplied from storage batteries shall be subject to the applicable provisions of this Code applying to wiring and equipment operating at the same voltage, unless otherwise permitted by 480.6. [480.5](https://2023.antflix.net#480.5) | https://2023.antflix.net#480.5 |
Chapter 4 Equipment for General Use | 480.6 | Overcurrent protection shall not be required for conductors from a battery with a voltage of 60 volts dc or less if the battery provides power for starting, ignition, or control of prime movers. Section 300.3 shall not apply to these conductors. [480.6](https://2023.antflix.net#480.6) | https://2023.antflix.net#480.6 |
Chapter 4 Equipment for General Use | 480.7(A) | A disconnecting means shall be provided for all ungrounded conductors derived from a stationary standby battery with a voltage over 60 volts dc. A disconnecting means shall be readily accessible and located within sight of the stationary standby battery. Informational Note: See 240.21 (H) for information on the location of the overcurrent device for battery conductors. [480.7(A)](https://2023.antflix.net#480.7(A)) | https://2023.antflix.net#480.7(A) |
Chapter 4 Equipment for General Use | 480.7(B) | For one-family and two-family dwellings, a disconnecting means or its remote control for a stationary standby battery shall be located at a readily accessible location outside the building for emergency use. The disconnect shall be labeled as follows: EMERGENCY DISCONNECT [480.7(B)](https://2023.antflix.net#480.7(B)) | https://2023.antflix.net#480.7(B) |
Chapter 4 Equipment for General Use | 480.7(C) | Battery circuits exceeding 240 volts dc nominal between conductors or to ground and subject to field servicing shall have provisions to disconnect the series-connected strings into segments not exceeding 240 volts dc nominal for maintenance by qualified persons. Non-load-break bolted or plug-in disconnects shall be permitted. [480.7(C)](https://2023.antflix.net#480.7(C)) | https://2023.antflix.net#480.7(C) |
Chapter 4 Equipment for General Use | 480.7(D) | Where a disconnecting means, located in accordance with 480.7(A), is provided with remote controls to activate the disconnecting means and the controls for the disconnecting means are not located within sight of the stationary standby battery, the disconnecting means shall be capable of being locked in the open position, in accordance with 110.25, and the location of the controls shall be field marked on the disconnecting means. [480.7(D)](https://2023.antflix.net#480.7(D)) | https://2023.antflix.net#480.7(D) |
Chapter 4 Equipment for General Use | 480.7(E) | Where a dc busway system is installed, the disconnecting means shall be permitted to be incorporated into the busway. [480.7(E)](https://2023.antflix.net#480.7(E)) | https://2023.antflix.net#480.7(E) |
Chapter 4 Equipment for General Use | 480.7(F) | The disconnecting means shall be legibly marked in the field. A label with the marking shall be placed in a conspicuous location near the battery if a disconnecting means is not provided. The marking shall be of sufficient durability to withstand the environment involved and shall include the following: Nominal battery voltageAvailable fault current derived from the stationary standby batteryInformational Note No. 1: Battery equipment suppliers can provide information about available fault current on specific battery models.An arc flash label in accordance with acceptable industry practiceInformational Note No. 2: See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for assistance in determining the severity of potential exposure, planning safe work practices, arc flash labeling, and selecting personal protective equipment.Date the calculation was performedException: List items (2), (3), and (4) shall not apply to one- and two-family dwellings. [480.7(F)](https://2023.antflix.net#480.7(F)) | https://2023.antflix.net#480.7(F) |
Chapter 4 Equipment for General Use | 480.7(G) | Stationary standby batteries shall be indicated by 480.7(G)(1) and (G)(2). [480.7(G)](https://2023.antflix.net#480.7(G)) | https://2023.antflix.net#480.7(G) |
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