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k disconnect switch designed to interrupt the service load. The purpose of the meter disconnect switch is to facilitate meter change, maintenance, or disconnecting of the service. A meter disconnect switch must have a short-circuit current rating that is not less than the available short-circuit cur...

k disconnect switch designed to interrupt the service load. The purpose of the meter disconnect switch is to facilitate meter change, maintenance, or disconnecting of the service. A meter disconnect switch must have a short-circuit current rating that is not less than the available short-circuit current at the line terminals of the meter disconnect switch. 230.85 Emergency Disconnects. For one- and two-family dwelling units, an emergency disconnecting means shall be installed. ENHANCED CONTENT Collapse This section recognizes the need for an outdoor disconnect for first responders. Prior to the 2020 NEC, first responders and utility personnel have not had a way to safely remove power from a structure. This requirement mandates that a means to disconnect the electric utility be located in a readily accessible, outdoor location. Mounting the emergency disconnect in a readily accessible location does not preclude locking the disconnect in the ?on? position. Replacement of the service equipment will now require the addition of the emergency disconnect, but not repair of service equipment or wiring. Additional labeling for emergency disconnects is required where alternate sources of power are not located adjacent to the disconnect, which will help ensure all sources of power to the structure are removed. (A) General. (1) Location. The disconnecting means shall be installed in a readily accessible outdoor location on or within sight of the dwelling unit. Exception: Where the requirements of 225.41 are met, this section shall not apply. (2) Rating. The disconnecting means shall have a short-circuit current rating equal to or greater than the available fault current. (3) Grouping. If more than one disconnecting means is provided, they shall be grouped. (B) Disconnects. Each disconnect shall be one of the following: * (1) Service disconnect * (2) A meter disconnect integral to the meter mounting equipment not marked as suitable only for use as service equipment installed in accordance with 230.82 * (3) Other listed disconnect switch or circuit breaker that is marked suitable for use as service equipment, but not marked as suitable only for use as service equipment, installed on the supply side of each service disconnect Informational Note 1: Conductors between the emergency disconnect and the service disconnect in 230.85(2) and 230.85(3) are service conductors. Informational Note 2: Equipment marked ?Suitable only for use as service equipment? includes the factory marking ?Service Disconnect?. (C) Replacement. Where service equipment is replaced, all of the requirements of this section shall apply. Exception: Where only meter sockets, service entrance conductors, or related raceways and fittings are replaced, the requirements of this section shall not apply. (D) Identification of Other Isolation Disconnects. Where equipment for isolation of other energy source systems is not located adjacent to the emergency disconnect required by this section, a plaque or directory identifying the location of all equipment for isolation of other energy sources shall be located adjacent to the disconnecting means required by this section. Informational Note: See 445.18, 480.7, 705.20, and 706.15 for examples of other energy source system isolation means. (E) Marking. (1) Marking Text. The disconnecting means shall marked as follows: * (1) Service disconnect EMERGENCY DISCONNECT, SERVICE DISCONNECT * (2) Meter disconnects installed in accordance with 230.82(3) and marked as follows: EMERGENCY DISCONNECT, METER DISCONNECT, NOT SERVICE EQUIPMENT * (3) Other listed disconnect switches or circuit breakers on the supply side of each service disconnect that are marked suitable for use as service equipment and marked as follows: EMERGENCY DISCONNECT, NOT SERVICE EQUIPMENT (2) Marking Location and Size. Markings shall comply with 110.21(B) and both of the following: * (1) The marking or labels shall be located on the outside front of the disconnect enclosure with red background and white text. * (2) The letters shall be at least 13 mm (1?2 in.) high. Part VII. Service Equipment ? Overcurrent Protection 230.90 Where Required. Each ungrounded service conductor shall have overload protection. ENHANCED CONTENT Collapse Service equipment is the main control and means of cutoff of the electrical supply to the premises wiring system. It is usually an overcurrent device, such as a circuit breaker or a fuse, installed in series with each ungrounded service conductor to provide overload protection only. The service overcurrent device does not protect the service conductors under short- circuit or ground-fault conditions on the line side of the disconnect. Protection against ground faults and short circuits is provided by the special requirements for service conductor protection and the location of the conductors. (A) Ungrounded Conductor. Such protection shall be provided by an overcurrent device in series with each ungrounded service conductor that has a rating or setting not higher than the ampacity of the conductor. A set of fuses shall be considered all the fuses required to protect all the ungrounded conductors of a circuit. Single-pole circuit breakers, grouped in accordance with 230.71(B), shall be considered as one protective device. Exception No. 1: For motor-starting currents, ratings that comply with 430.52, 430.62, and 430.63 shall be permitted. Exception No. 2: Fuses and circuit breakers with a rating or setting that complies with 240.4(B) or (C) and 240.6 shall be permitted. Exception No. 3: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided the calculated load does not exceed the ampacity of the service conductors. Exception No. 4: Overload protection for fire pump supply conductors shall comply with 695.4(B)(2)(a). Exception No. 5: Overload protection in accordance with the conductor ampacities of 310.12 shall be permitted for single-phase dwelling services. ENHANCED CONTENT Collapse Exception No. 2. Where the conductor ampacity does not correspond to the standard ampere rating of a circuit breaker or fuse, this exception permits the next-larger standard size circuit breaker or fuse to be installed. The permission to ?round up? is limited by 240.4(B)(3) to ratings not exceeding 800 amperes. This exception permits rounding up only to the next standard size fuse or circuit breaker rating and does not permit the load to exceed the allowable ampacity of the service conductors. See also 240.6 for standard ampere ratings of fuses and circuit breakers. Exception No. 3. Section 230.90 requires an overcurrent device to provide overload protection in each ungrounded service conductor. However, Exception No. 3 allows two to six circuit breakers or sets of fuses to be considered as the overcurrent device. None of the individual overcurrent devices can have a rating or setting higher than the ampacity of the service conductors. In complying with these rules, it is possible for the total of the six overcurrent devices to be greater than the rating of the service-entrance conductors. However, the size of the service-entrance conductors is required to be adequate for the computed load only, and each individual service disconnecting means is required to be large enough for the individual load it supplies. The combined ratings of the five service disconnecting means OCPDs (350 amperes) shown in the exhibit below exceed the ampacity of the service-entrance conductors (310 amperes) permitted by this exception. As specified, the ampacity of the service-entrance conductors is sufficient to carry the calculated load. The combined rating of the five service disconnecting means also complies with 230.80, which requires that the combined rating (350 amperes) not be less than the calculated load (305 amperes), the minimum size required for the service OCPD specified by 240.4 and 230.80. (B) Not in Grounded Conductor. No overcurrent device shall be inserted in a grounded service conductor except a circuit breaker that simultaneously opens all conductors of the circuit. 230.91 Location. The service overcurrent device shall be an integral part of the service disconnecting means or shall be located immediately adjacent thereto. Where fuses are used as the service overcurrent device, the disconnecting means shall be located ahead of the supply side of the fuses. 230.92 Locked Service Overcurrent Devices. Where the service overcurrent devices are locked or sealed or are not readily accessible to the occupant, branch-circuit or feeder overcurrent devices shall be installed on the load side, shall be mounted in a readily accessible location, and shall be of lower ampere rating than the service overcurrent device. 230.93 Protection of Specific Circuits. Where necessary to prevent tampering, an automatic overcurrent device that protects service conductors supplying only a specific load, such as a water heater, shall be permitted to be locked or sealed where located so as to be accessible. 230.94 Relative Location of Overcurrent Device and Other Service Equipment. The overcurrent device shall protect all circuits and devices. Exception No. 1: The service switch shall be permitted on the supply side. Exception No. 2: High-impedance shunt circuits, surge arresters, Type 1 surge-protective devices, surge- protective capacitors, and instrument transformers (current and voltage) shall be permitted to be connected and installed on the supply side of the service disconnecting means as permitted by 230.82. Exception No. 3: Circuits for load management devices shall be permitted to be connected on the supply side of the service overcurrent device where separately provided with overcurrent protection. Exception No. 4: Circuits used only for the operation of fire alarm, other protective signaling systems, or the supply to fire pump equipment shall be permitted to be connected on the supply side of the service overcurrent device where separately provided with overcurrent protection. Exception No. 5: Meters nominally rated not in excess of 600 volts shall be permitted, provided all metal housings and service enclosures are grounded. Exception No. 6: Where service equipment is power operable, the control circuit shall be permitted to be connected ahead of the service equipment if suitable overcurrent protection and disconnecting means are provided. 230.95 Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall be provided for solidly grounded wye electric services of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each service disconnect rated 1000 amperes or more. The grounded conductor for the solidly grounded wye system shall be connected directly to ground through a grounding electrode system, as specified in 250.50, without inserting any resistor or impedance device. The rating of the service disconnect shall be considered to be the rating of the largest fuse that can be installed or the highest continuous current trip setting for which the actual overcurrent device installed in a circuit breaker is rated or can be adjusted. Exception: The ground-fault protection provisions of this section shall not apply to a service disconnect for a continuous industrial process where a nonorderly shutdown will introduce additional or increased hazards. ENHANCED CONTENT Collapse Ground-fault protection of equipment (GFPE) for service disconnecting means was first required in the 1971 edition of the NEC due to the unusually high number of equipment burndowns reported on large capacity 480Y/277-volt solidly grounded services. Other solidly grounded, wye-connected systems (e.g., 600Y/347 volts) are covered within the parameters specified by this section. The requirement does not apply to systems where the grounded conductor is not solidly grounded, as is the case with impedance grounded systems covered in 250.36. Ground-fault protection of services does not protect the conductors on the supply side of the service disconnecting means, but it is designed to provide protection from line-to- ground faults that occur on the load side of the service disconnecting means. The two basic types of ground-fault equipment protectors are illustrated in the following two exhibits. In the exhibit below, the ground-fault sensor is installed around all the circuit conductors, and a stray current on a line-to-ground fault sets up an imbalance of the currents flowing in individual conductors installed through the ground-fault sensor. When this current exceeds the setting of the ground-fault sensor, the shunt trip operates and opens the circuit breakers. The ground-fault sensor illustrated below is installed around the bonding jumper only. When an unbalanced current from a line-to-ground fault occurs, the current flows through the bonding jumper and the shunt trip causes the circuit breaker to operate, removing the load from the line. Setting. The ground-fault protection system shall operate to cause the service disconnect to open all ungrounded conductors of the faulted circuit. The maximum setting of the ground-fault protection shall be 1200 amperes, and the maximum time delay shall be one second for ground-fault currents equal to or greater than 3000 amperes. ENHANCED CONTENT Collapse Ground-fault sensor settings at low levels can increase the likelihood of unwanted shutdowns. The duration of the fault is limited to not more than 1 second for fault currents greater than 3000 amperes. This restriction minimizes the amount of damage done by an arcing fault, which is directly proportional to the time the arcing fault is allowed to burn. Care should be taken to ensure that interconnecting of multiple supply systems does not interfere with proper sensing by the GFPE. An engineering study should be made to ensure that fault currents do not take parallel paths to the supply system, thereby bypassing the ground-fault detection device. Fuses. If a switch and fuse combination is used, the fuses employed shall be capable of interrupting any current higher than the interrupting capacity of the switch during a time that the ground-fault protective system will not cause the switch to open. Performance Testing. The ground-fault protection system shall be performance tested when first installed on site. This testing shall be conducted by a qualified person(s) using a test process of primary current injection, in accordance with instructions that shall be provided with the equipment. A written record of this testing shall be made and shall be available to the authority having jurisdiction. Informational Note No. 1: Ground-fault protection that functions to open the service disconnect affords no protection from faults on the line side of the protective element. It serves only to limit damage to conductors and equipment on the load side in the event of an arcing ground fault on the load side of the protective element. Informational Note No. 2: This added protective equipment at the service equipment could make it necessary to review the overall wiring system for proper selective overcurrent protection coordination. Additional installations of ground-fault protective equipment might be needed on feeders and branch circuits where maximum continuity of electric service is necessary. Informational Note No. 3: Where ground-fault protection is provided for the service disconnect and interconnection is made with another supply system by a transfer device, means or devices could be needed to ensure proper ground-fault sensing by the ground-fault protection equipment. Informational Note No. 4: See 517.17(A) for information on where an additional step of ground-fault protection is required for hospitals and other buildings with critical areas or life support equipment. Article 235 Branch Circuits, Feeders, and Services Over 1000 Volts ac, 1500 Volts dc, Nominal Part I. General 235.1 Scope. This article provides the general requirements for branch circuits, feeders, and services over 1000 volts ac or 1500 volts dc, nominal. Informational Note: See ANSI/IEEE C2-2017, National Electrical Safety Code, for additional information on wiring over 1000 volts, nominal. ENHANCED CONTENT Collapse New Article 235 has been created to cover branch circuits, feeders, and services for installations over 1000 volts ac, 1500 volts dc, nominal. To aid in usability of the NEC, much of the information within Article 235 has been pulled in from long-standing, medium-voltage requirements within other code articles, such as Articles 210, 215, 225, and 230. Part II. Branch Circuits 235.3 Other Articles for Specific-Purpose Branch Circuits. Table 235.3 lists references for specific equipment and applications not located in Chapters 5, 6, and 7 that amend or supplement the requirements of this article. Table 235.3 References for Specific Equipment and Applications Not Located in Chapters 5, 6, and 7 Equipment Article Section Air-conditioning and refrigerating equipment 440.6, 440.31, and 440.32 Busways 368.17 Central heating equipment other than fixed electric space-heating equipment 422.12 Fixed electric heating equipment for pipelines and vessels 427.4 Fixed electric space-heating equipment 424.4 Fixed outdoor electrical deicing and snow- melting equipment 426.4 Infrared lamp industrial heating equipment 422.48 and 424.3 Motors, motor circuits, and controllers 430 235.5 Conductor Identification for Branch Circuits. (A) Grounded Conductor. The grounded conductor of a branch circuit shall be identified in accordance with 200.6. (B) Equipment Grounding Conductor. The equipment grounding conductor shall be identified in accordance with 250.119. (C) Ungrounded Conductors. Ungrounded conductors shall be identified in accordance with 235.5(C)(1) or (C)(2), as applicable. (1) Branch Circuits Supplied from More Than One Nominal Voltage System. Where the premises wiring system has branch circuits supplied from more than one nominal voltage system, each ungrounded conductor of a branch circuit shall be identified by phase or line and by nominal system voltage at all termination, connection, and splice points in accordance with 235.5(C)(1)(a) and (C)(1)(b). Different systems within the same premises that have the same nominal voltage shall be permitted to use the same identification. * (a) Means of Identification. The means of identification shall be permitted to be by separate color coding, marking tape, tagging, or other approved means. * (b) Posting of Identification Means. The method used for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or shall be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment. The label shall be of sufficient durability to withstand the environment involved and shall not be handwritten. Exception: In existing installations where a voltage system(s) already exists and a different voltage system is being added, it shall be permissible to mark only the new system voltage. Existing unidentified systems shall not be required to be identified at each termination, connection, and splice point in accordance with 235.5(C)(1)(a) and (C)(1)(b). Labeling shall be required at each voltage system distribution equipment to identify that only one voltage system has been marked for a new system(s). The new system label(s) shall include the words “other unidentified systems exist on the premises.” (2) Branch Circuits Supplied from Direct-Current Systems. Where a branch circuit is supplied from a dc system operating at more than 1500 volts, each ungrounded conductor of 4 AWG or larger shall be identified by polarity at all termination, connection, and splice points by marking tape, tagging, or other approved means and each ungrounded conductor of 6 AWG or smaller shall be identified by polarity at all termination, connection, and splice points in compliance with 235.5(C)(2)(a) and (C)(2)(b). The identification methods used for conductors originating within each branch-circuit panelboard or similar branch-circuit distribution equipment shall be documented in a manner that is readily available or be permanently posted at each branch-circuit panelboard or similar branch-circuit distribution equipment. * (a) Positive Polarity, Sizes 6 AWG or Smaller. Where the positive polarity of a dc system does not serve as the connection point for the grounded conductor, each positive ungrounded conductor shall be identified by one of the following means: o (1) A continuous red outer finish o (2) A continuous red stripe durably marked along the conductor’s entire length on insulation of a color other than green, white, gray, or black o (3) Imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B) o (4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted plus signs (+) or the word POSITIVE or POS durably marked on insulation of a color other than green, white, gray, or black * (b) Negative Polarity, Sizes 6 AWG or Smaller. Where the negative polarity of a dc system does not serve as the connection point for the grounded conductor, each negative ungrounded conductor shall be identified by one of the following means: o (1) A continuous black outer finish o (2) A continuous black stripe durably marked along the conductor’s entire length on insulation of a color other than green, white, gray, or red o (3) Imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red and repeated at intervals not exceeding 610 mm (24 in.) in accordance with 310.8(B) o (4) An approved permanent marking means such as sleeving or shrink-tubing that is suitable for the conductor size, at all termination, connection, and splice points, with imprinted minus signs (-) or the word NEGATIVE or NEG durably marked on insulation of a color other than green, white, gray, or red 235.6 Branch-Circuit Voltage Limitations Over 1000 volts ac or 1500 volts dc, Nominal, Between Conductors. Circuits exceeding 1000 volts ac or 1500 volts dc, nominal, between conductors shall be permitted to supply utilization equipment in installations where conditions of maintenance and supervision ensure that only qualified persons service the installation. 235.9 Circuits Derived from Autotransformers. Branch circuits shall not be derived from autotransformers unless the circuit supplied has a grounded conductor that is electrically connected to a grounded conductor of the system supplying the autotransformer. 235.10 Ungrounded Conductors Tapped from Grounded Systems. Two-wire dc circuits and ac circuits of two or more ungrounded conductors shall be permitted to be tapped from the ungrounded conductors of circuits that have a grounded neutral conductor. Switching devices in each tapped circuit shall have a pole in each ungrounded conductor. All poles of multipole switching devices shall manually switch together where such switching devices also serve as a disconnecting means as required by the following sections: * (1) 410.93 for double-pole switched lampholders * (2) 410.104(B) for electric-discharge lamp auxiliary equipment switching devices * (3) 422.31(B) for an appliance * (4) 424.20 for a fixed electric space-heating unit * (5) 426.51 for electric deicing and snow-melting equipment * (6) 430.85 for a motor controller * (7) 430.103 for a motor 235.11 Branch Circuits Required. The minimum number of branch circuits shall be determined from the total calculated load and the size or rating of the circuits used. In all installations, the number of circuits shall be sufficient to supply the load served. 235.18 Rating. Branch circuits recognized by this article sh