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Article 240

  1. Overcurrent ProtectionTable 240.3 Other Articles
    imageimageEquipment ArticleAir-conditioning and refrigerating equipment440Part I. General240.1 Scope. Parts I through VII of this article provide theAppliances 422Assembly occupancies 518general requirements for overcurrent protection and overcur‐ rent protective devices not more than 1000 volts, nominal. Part VIII covers overcurrent protection for those portions ofAudio signal processing, amplification, and reproduction equipment640supervised industrial installations operating at voltages of not more than 1000 volts, nominal. Part IX covers overcurrent protection over 1000 volts, nominal.Branch circuits 210Busways 368Capacitors 460Informational Note: Overcurrent protection for conductors and equipment is provided to open the circuit if the current reachesClass 1, Class 2, and Class 3 remote-control, signaling, and power- limited circuits725a value that will cause an excessive or dangerous temperature inconductors or conductor insulation. See also 110.9 for require‐ ments for interrupting ratings and 110.10 for requirements for protection against fault currents.Cranes and hoists 610Electric signs and outline lighting 600Electric welders 630Electrolytic cells 668240.2 Definitions.Current-Limiting Overcurrent Protective Device. A device that,Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chairlifts620when interrupting currents in its current-limiting range,reduces the current flowing in the faulted circuit to a magni‐ tude substantially less than that obtainable in the same circuit ifEmergency systems 700Fire alarm systems 760Fire pumps 695the device were replaced with a solid conductor having compa‐ rable impedance.Supervised Industrial Installation. For the purposes of Part VIII, the industrial portions of a facility where all of the following conditions are met:Fixed electric heating equipment for pipelines and vesselsFixed electric space-heating equipmentFixed outdoor electric deicing and snow-melting equipment427
    424
    426
    1. Conditions of maintenance and engineering supervisionensure that only qualified persons monitor and serviceGenerators 445Health care facilities 517the system.
    2. The premises wiring system has 2500 kVA or greater of

Induction and dielectric heating equipment

665

load used in industrial process(es), manufacturing activi‐ ties, or both, as calculated in accordance with Article 220.

Industrial machinery 670

Luminaires, lampholders, and lamps 410

(3) The premises has at least one service or feeder that is more than 150 volts to ground and more than 300 volts phase-to-phase.

This definition excludes installations in buildings used by

Motion picture and television studios and similar locations

Motors, motor circuits, and controllers

530

430

the industrial facility for offices, warehouses, garages, machine shops, and recreational facilities that are not an integral part of the industrial plant, substation, or control center.

Tap Conductor. A conductor, other than a service conductor, that has overcurrent protection ahead of its point of supply

Phase converters 455

Pipe organs 650

Receptacles 406

Services 230

Solar photovoltaic systems 690

Switchboards and panelboards 408

that exceeds the value permitted for similar conductors that are protected as described elsewhere in 240.4.

Theaters, audience areas of motion

picture and television studios, and similar locations

520

  1. Other Articles. Equipment shall be protected againstovercurrent in accordance with the article in this Code that covers the type of equipment specified in Table 240.3.
  2. Protection of Conductors. Conductors, other than flex‐ ible cords, flexible cables, and fixture wires, shall be protected against overcurrent in accordance with their ampacities speci‐ fied in 310.15, unless otherwise permitted or required in 240.4(A) through (G).Informational Note: See ICEA P-32-382-2007 for information on allowable short-circuit currents for insulated copper and alumi‐ num conductors.Transformers and transformer vaults 450X-ray equipment 660
    1. Power Loss Hazard. Conductor overload protection shall not be required where the interruption of the circuit would create a hazard, such as in a material-handling magnet circuit or fire pump circuit. Short-circuit protection shall be provided.Informational Note: See NFPA 20-2013, Standard for the Installa‐ tion of Stationary Pumps for Fire Protection.
    2. Overcurrent Devices Rated 800 Amperes or Less. The next higher standard overcurrent device rating (above the ampacity of the conductors being protected) shall be permitted to be used, provided all of the following conditions are met:
      1. The conductors being protected are not part of a branch circuit supplying more than one receptacle for cord-and- plug-connected portable loads.
      2. The ampacity of the conductors does not correspond with the standard ampere rating of a fuse or a circuit breaker without overload trip adjustments above its rating (but that shall be permitted to have other trip or rating adjust‐ ments).
      3. The next higher standard rating selected does not exceed 800 amperes.
    3. Overcurrent Devices Rated over 800 Amperes. Where the overcurrent device is rated over 800 amperes, the ampacity of the conductors it protects shall be equal to or greater than the rating of the overcurrent device defined in 240.6.
    4. Small Conductors. Unless specifically permitted in 240.4(E) or (G), the overcurrent protection shall not exceed that required by (D)(1) through (D)(7) after any correction factors for ambient temperature and number of conductors have been applied.
      1. 18 AWG Copper. 7 amperes, provided all the following conditions are met:
    1. 240.21, Location in Circuit
    2. 368.17(B), Reduction in Ampacity Size of Busway
    3. 368.17(C), Feeder or Branch Circuits (busway taps)
    4. 430.53(D), Single Motor Taps
    1. Transformer Secondary Conductors. Single-phase (other than 2-wire) and multiphase (other than delta-delta, 3-wire) transformer secondary conductors shall not be considered to be protected by the primary overcurrent protective device. Conductors supplied by the secondary side of a single-phase transformer having a 2-wire (single-voltage) secondary, or a three-phase, delta-delta connected transformer having a 3-wire (single-voltage) secondary, shall be permitted to be protected by overcurrent protection provided on the primary (supply) side of the transformer, provided this protection is in accord‐ ance with 450.3 and does not exceed the value determined by multiplying the secondary conductor ampacity by the secondary-to-primary transformer voltage ratio.
    2. Overcurrent Protection for Specific Conductor Applica‐ tions. Overcurrent protection for the specific conductors shall be permitted to be provided as referenced in Table 240.4(G).
      Table 240.4(G) Specific Conductor Applications
      1. Continuous loads do not exceed 5.6 amperes.                                                                                                                                
      2. Overcurrent protection is provided by one of the follow‐ ing:Conductor Article Sectionimage
        1. Branch-circuit-rated circuit breakers listed and marked for use with 18 AWG copper wire
        2. Branch-circuit-rated fuses listed and marked for use with 18 AWG copper wire
        3. Class CC, Class J, or Class T fuses
    (2) 16 AWG Copper. 10 amperes, provided all the following conditions are met:
    1. Continuous loads do not exceed 8 amperes.
    2. Overcurrent protection is provided by one of the follow‐ ing:
      1. Branch-circuit-rated circuit breakers listed and marked for use with 16 AWG copper wire
      2. Branch-circuit-rated fuses listed and marked for use with 16 AWG copper wire
      3. Class CC, Class J, or Class T fuses
    3. 14 AWG Copper. 15 amperes
    4. 12 AWG Aluminum and Copper-Clad Aluminum. 15 amperes
    5. 12 AWG Copper. 20 amperes
    6. 10 AWG Aluminum and Copper-Clad Aluminum. 25 amperes
    7. 10 AWG Copper. 30 amperes
    (E) Tap Conductors. Tap conductors shall be permitted to be protected against overcurrent in accordance with the following:Air-conditioning andrefrigeration equipment circuit conductorsCapacitor circuit conductorsControl and instrumentation circuit conductors (Type ITC)Electric welder circuit conductorsFire alarm system circuit conductors
    Motor-operated appliance circuit conductorsMotor and motor- control circuit conductorsPhase converter supply conductorsRemote-control, signaling, and power- limited circuit conductors440, Parts III,VI
    460 460.8(B) and460.25(A)–(D)727 727.9
    630 630.12 and 630.32
    760 760.43, 760.45,760.121, andChapter 9, Tables 12(A) and 12(B)422, Part II
    430, Parts II, III, IV, V, VI,VII455 455.7
    725 725.43, 725.45,725.121, andChapter 9, Tables 11(A) and 11(B)
    1. 210.19(A)(3) and (A)(4), Household Ranges and Cook‐ ing Appliances and Other Loads
    2. 240.5(B)(2), Fixture Wire
    Secondary tie conductors 450 450.6
  3. Protection of Flexible Cords, Flexible Cables, and Fixture Wires. Flexible cord and flexible cable, including tinsel cord and extension cords, and fixture wires shall be
    N Table 240.6(A) Standard Ampere Ratings for Fuses and Inverse Time Circuit Breakersprotected against overcurrent by either 240.5(A) or (B).                                                                                                                                
    1. Ampacities. Flexible cord and flexible cable shall be protected by an overcurrent device in accordance with their ampacity as specified in Table 400.5(A)(1) and Table 400.5(A)(2). Fixture wire shall be protected against overcur‐ rent in accordance with its ampacity as specified in Table 402.5. Supplementary overcurrent protection, as covered in 240.10, shall be permitted to be an acceptable means for providing this protection.
    2. Branch-Circuit Overcurrent Device. Flexible cord shall be protected, where supplied by a branch circuit, in accordance with one of the methods described in 240.5(B)(1), (B)(3), or (B)(4). Fixture wire shall be protected, where supplied by a branch circuit, in accordance with 240.5(B)(2).
      1. Supply Cord of Listed Appliance or Luminaire. Where flexible cord or tinsel cord is approved for and used with a specific listed appliance or luminaire, it shall be considered to be protected when applied within the appliance or luminaire listing requirements. For the purposes of this section, a lumin‐ aire may be either portable or permanent.
      2. Fixture Wire. Fixture wire shall be permitted to be tapped to the branch-circuit conductor of a branch circuit in accord‐ ance with the following:
    1. 20-ampere circuits — 18 AWG, up to 15 m (50 ft) of run length
    2. 20-ampere circuits — 16 AWG, up to 30 m (100 ft) of run length
    3. 20-ampere circuits — 14 AWG and larger
    4. 30-ampere circuits — 14 AWG and larger
    5. 40-ampere circuits — 12 AWG and larger
    6. 50-ampere circuits — 12 AWG and larger
    1. Extension Cord Sets. Flexible cord used in listed exten‐ sion cord sets shall be considered to be protected when applied within the extension cord listing requirements.
    2. Field Assembled Extension Cord Sets. Flexible cord used in extension cords made with separately listed and installed components shall be permitted to be supplied by a branch circuit in accordance with the following:
    20-ampere circuits — 16 AWG and larger
  4. Standard Ampere Ratings.
  1. Fuses and Fixed-Trip Circuit Breakers. The standard ampere ratings for fuses and inverse time circuit breakers shall be considered as shown in Table 240.6(A). Additional standard ampere ratings for fuses shall be 1, 3, 6, 10, and 601. The use of fuses and inverse time circuit breakers with nonstandard ampere ratings shall be permitted.
  2. Adjustable-Trip Circuit Breakers. The rating of adjustable-trip circuit breakers having external means for adjusting the current setting (long-time pickup setting), not meeting the requirements of 240.6(C), shall be the maximum setting possible.
  3. Restricted Access Adjustable-Trip Circuit Breakers. A circuit breaker(s) that has restricted access to the adjusting means shall be permitted to have an ampere rating(s) that is equal to the adjusted current setting (long-time pickup

Standard Ampere Ratings

image

15 20 25 30 35

4045506070
8090100110125
150175200225250
300350400450500
60070080010001200
16002000250030004000
50006000———

setting). Restricted access shall be defined as located behind one of the following:

  1. Removable and sealable covers over the adjusting means
  2. Bolted equipment enclosure doors
  3. Locked doors accessible only to qualified personnel
  1. Fuses or Circuit Breakers in Parallel. Fuses and circuit breakers shall be permitted to be connected in parallel where they are factory assembled in parallel and listed as a unit. Indi‐ vidual fuses, circuit breakers, or combinations thereof shall not otherwise be connected in parallel.
  2. Thermal Devices. Thermal relays and other devices not designed to open short circuits or ground faults shall not be used for the protection of conductors against overcurrent due to short circuits or ground faults, but the use of such devices shall be permitted to protect motor branch-circuit conductors from overload if protected in accordance with 430.40.
  3. Supplementary Overcurrent Protection. Where supplementary overcurrent protection is used for luminaires, appliances, and other equipment or for internal circuits and components of equipment, it shall not be used as a substitute for required branch-circuit overcurrent devices or in place of the required branch-circuit protection. Supplementary over‐ current devices shall not be required to be readily accessible.
  1. Electrical System Coordination. Where an orderly shutdown is required to minimize the hazard(s) to personnel and equipment, a system of coordination based on the follow‐ ing two conditions shall be permitted:
    1. Coordinated short-circuit protection
    2. Overload indication based on monitoring systems or devices
    Informational Note: The monitoring system may cause the condition to go to alarm, allowing corrective action or an orderly shutdown, thereby minimizing personnel hazard and equipment damage.
  2. Ground-Fault Protection of Equipment. Ground-fault protection of equipment shall be provided in accordance with the provisions of 230.95 for solidly grounded wye electrical systems of more than 150 volts to ground but not exceeding 1000 volts phase-to-phase for each individual device used as a building or structure main disconnecting means rated 1000 amperes or more.
    The provisions of this section shall not apply to the discon‐ necting means for the following:
    1. Continuous industrial processes where a nonorderly shut‐ down will introduce additional or increased hazards
    2. Installations where ground-fault protection is provided by other requirements for services or feeders
    3. Fire pumps

240.15 Ungrounded Conductors.

  1. Overcurrent Device Required. A fuse or an overcurrent trip unit of a circuit breaker shall be connected in series with each ungrounded conductor. A combination of a current trans‐ former and overcurrent relay shall be considered equivalent to an overcurrent trip unit.Informational Note: For motor circuits, see Parts III, IV, V, and XI of Article 430.
  2. Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in 240.15(B)(1), (B)(2), (B)(3), and (B)(4).
    1. Multiwire Branch Circuits. Individual single-pole circuit breakers, with identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads.
    2. Grounded Single-Phase Alternating-Current Circuits. In grounded systems, individual single-pole circuit breakers rated 120/240 volts ac, with identified handle ties, shall be permitted as the protection for each ungrounded conductor for line-to- line connected loads for single-phase circuits.
    3. 3-Phase and 2-Phase Systems. For line-to-line loads in 4-wire, 3-phase systems or 5-wire, 2-phase systems, individual single-pole circuit breakers rated 120/240 volts ac with identi‐ fied handle ties shall be permitted as the protection for each ungrounded conductor, if the systems have a grounded neutral point and the voltage to ground does not exceed 120 volts.
    4. 3-Wire Direct-Current Circuits. Individual single-pole circuit breakers rated 125/250 volts dc with identified handle ties shall be permitted as the protection for each ungrounded conductor for line-to-line connected loads for 3-wire, direct- current circuits supplied from a system with a grounded neutral where the voltage to ground does not exceed 125 volts.

Part II. Location

240.21 Location in Circuit. Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

  1. Branch-Circuit Conductors. Branch-circuit tap conductors meeting the requirements specified in 210.19 shall be permit‐ ted to have overcurrent protection as specified in 210.20.
  2. Feeder Taps. Conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder as speci‐ fied in 240.21(B)(1) through (B)(5). The provisions of 240.4(B) shall not be permitted for tap conductors.(1) Taps Not over 3 m (10 ft) Long. If the length of the tap conductors does not exceed 3 m (10 ft) and the tap conductors comply with all of the following:
    1. The ampacity of the tap conductors is
      1. Not less than the combined calculated loads on the circuits supplied by the tap conductors, and
      2. Not less than the rating of the equipment containing an overcurrent device(s) supplied by the tap conduc‐ tors or not less than the rating of the overcurrent protective device at the termination of the tap conductors.Exception to b: Where listed equipment, such as a surge protective device(s) [SPD(s)], is provided with specific instructions on mini‐ mum conductor sizing, the ampacity of the tap conductors supply‐ ing that equipment shall be permitted to be determined based on the manufacturer’s instructions.
    2. The tap conductors do not extend beyond the switch‐ board, switchgear, panelboard, disconnecting means, or control devices they supply.
    3. Except at the point of connection to the feeder, the tap conductors are enclosed in a raceway, which extends from the tap to the enclosure of an enclosed switchboard, switchgear, a panelboard, or control devices, or to the back of an open switchboard.
    4. For field installations, if the tap conductors leave the enclosure or vault in which the tap is made, the ampacity of the tap conductors is not less than one-tenth of the rating of the overcurrent device protecting the feeder conductors.
    Informational Note: For overcurrent protection requirements for panelboards, see 408.36.(2) Taps Not over 7.5 m (25 ft) Long. Where the length of the tap conductors does not exceed 7.5 m (25 ft) and the tap conductors comply with all the following:
    1. The ampacity of the tap conductors is not less than one- third of the rating of the overcurrent device protecting the feeder conductors.
    2. The tap conductors terminate in a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This device shall be permitted to supply any number of additional overcurrent devices on its load side.
    3. The tap conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
    (3) Taps Supplying a Transformer [Primary Plus Secondary Not over 7.5 m (25 ft) Long]. Where the tap conductors supply a transformer and comply with all the following condi‐ tions:
    1. The conductors supplying the primary of a transformer have an ampacity at least one-third the rating of the over‐ current device protecting the feeder conductors.
    2. The conductors supplied by the secondary of the trans‐ former shall have an ampacity that is not less than the value of the primary-to-secondary voltage ratio multiplied by one-third of the rating of the overcurrent device protecting the feeder conductors.
    3. The total length of one primary plus one secondary conductor, excluding any portion of the primary conduc‐ tor that is protected at its ampacity, is not over 7.5 m (25 ft).
    4. The primary and secondary conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
    5. The secondary conductors terminate in a single circuit breaker or set of fuses that limit the load current to not more than the conductor ampacity that is permitted by 310.15.
    (4) Taps over 7.5 m (25 ft) Long. Where the feeder is in a high bay manufacturing building over 11 m (35 ft) high at walls and the installation complies with all the following conditions:
    1. Conditions of maintenance and supervision ensure that only qualified persons service the systems.
    2. The tap conductors are not over 7.5 m (25 ft) long hori‐ zontally and not over 30 m (100 ft) total length.
    3. The ampacity of the tap conductors is not less than one- third the rating of the overcurrent device protecting the feeder conductors.
    4. The tap conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the tap conductors. This single overcurrent device shall be permitted to supply any number of additional overcur‐ rent devices on its load side.
    5. The tap conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
    6. The tap conductors are continuous from end-to-end and contain no splices.
    7. The tap conductors are sized 6 AWG copper or 4 AWG aluminum or larger.
    8. The tap conductors do not penetrate walls, floors, or ceil‐ ings.
    9. The tap is made no less than 9 m (30 ft) from the floor.
    (5) Outside Taps of Unlimited Length. Where the conductors are located outside of a building or structure, except at the point of load termination, and comply with all of the following conditions:
    1. The tap conductors are protected from physical damage in an approved manner.
    2. The tap conductors terminate at a single circuit breaker or a single set of fuses that limits the load to the ampacity of the tap conductors. This single overcurrent device shall be permitted to supply any number of additional overcur‐ rent devices on its load side.
    3. The overcurrent device for the tap conductors is an inte‐ gral part of a disconnecting means or shall be located immediately adjacent thereto.
    4. The disconnecting means for the tap conductors is instal‐ led at a readily accessible location complying with one of the following:
      1. Outside of a building or structure
      2. Inside, nearest the point of entrance of the tap conductors
      3. Where installed in accordance with 230.6, nearest the point of entrance of the tap conductors
  3. Transformer Secondary Conductors. A set of conductors feeding a single load, or each set of conductors feeding sepa‐ rate loads, shall be permitted to be connected to a transformer secondary, without overcurrent protection at the secondary, asspecified in 240.21(C)(1) through (C)(6). The provisions of 240.4(B) shall not be permitted for transformer secondary conductors.Informational Note: For overcurrent protection requirements for transformers, see 450.3.
    1. Protection by Primary Overcurrent Device. Conductors supplied by the secondary side of a single-phase transformer having a 2-wire (single-voltage) secondary, or a three-phase, delta-delta connected transformer having a 3-wire (single- voltage) secondary, shall be permitted to be protected by over‐ current protection provided on the primary (supply) side of the transformer, provided this protection is in accordance with450.3 and does not exceed the value determined by multiplying the secondary conductor ampacity by the secondary-to-primary transformer voltage ratio.Single-phase (other than 2-wire) and multiphase (other than delta-delta, 3-wire) transformer secondary conductors are not considered to be protected by the primary overcurrent protec‐ tive device.
    2. Transformer Secondary Conductors Not over 3 m (10 ft) Long. If the length of secondary conductor does not exceed 3 m (10 ft) and complies with all of the following:
    1. The ampacity of the secondary conductors is
      1. Not less than the combined calculated loads on the circuits supplied by the secondary conductors, and
      2. Not less than the rating of the equipment containing an overcurrent device(s) supplied by the secondary conductors or not less than the rating of the overcur‐ rent protective device at the termination of the secon‐ dary conductors.Exception: Where listed equipment, such as a surge protective device(s) [SPD(s)], is provided with specific instructions on mini‐ mum conductor sizing, the ampacity of the tap conductors supply‐ ing that equipment shall be permitted to be determined based on the manufacturer’s instructions.
    2. The secondary conductors do not extend beyond the switchboard, switchgear, panelboard, disconnecting means, or control devices they supply.
    3. The secondary conductors are enclosed in a raceway, which shall extend from the transformer to the enclosure of an enclosed switchboard, switchgear, a panelboard, or control devices or to the back of an open switchboard.
    4. For field installations where the secondary conductors leave the enclosure or vault in which the supply connec‐ tion is made, the rating of the overcurrent device protect‐ ing the primary of the transformer, multiplied by the primary to secondary transformer voltage ratio, shall not exceed 10 times the ampacity of the secondary conductor.
    Informational Note: For overcurrent protection requirements for panelboards, see 408.36.(3) Industrial Installation Secondary Conductors Not over7.5 m (25 ft) Long. For the supply of switchgear or switch‐ boards in industrial installations only, where the length of the secondary conductors does not exceed 7.5 m (25 ft) and complies with all of the following:
    1. Conditions of maintenance and supervision ensure that only qualified persons service the systems.
    2. The ampacity of the secondary conductors is not less than the secondary current rating of the transformer, and the
      sum of the ratings of the overcurrent devices does not exceed the ampacity of the secondary conductors.
    3. All overcurrent devices are grouped.
    4. The secondary conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
    (4) Outside Secondary Conductors. Where the conductors are located outside of a building or structure, except at the point of load termination, and comply with all of the following conditions:
    1. The conductors are protected from physical damage in an approved manner.
    2. The conductors terminate at a single circuit breaker or a single set of fuses that limit the load to the ampacity of the conductors. This single overcurrent device shall be permitted to supply any number of additional overcur‐ rent devices on its load side.
    3. The overcurrent device for the conductors is an integral part of a disconnecting means or shall be located immedi‐ ately adjacent thereto.
    4. The disconnecting means for the conductors is installed at a readily accessible location complying with one of the following:
      1. Outside of a building or structure
      2. Inside, nearest the point of entrance of the conduc‐ tors
      3. Where installed in accordance with 230.6, nearest the point of entrance of the conductors
    5. Secondary Conductors from a Feeder Tapped Trans‐ former. Transformer secondary conductors installed in accordance with 240.21(B)(3) shall be permitted to have over‐ current protection as specified in that section.
    6. Secondary Conductors Not over 7.5 m (25 ft) Long.
    Where the length of secondary conductor does not exceed7.5 m (25 ft) and complies with all of the following:
    1. The secondary conductors shall have an ampacity that is not less than the value of the primary-to-secondary volt‐ age ratio multiplied by one-third of the rating of the over‐ current device protecting the primary of the transformer.
    2. The secondary conductors terminate in a single circuit breaker or set of fuses that limit the load current to not more than the conductor ampacity that is permitted by 310.15.
    3. The secondary conductors are protected from physical damage by being enclosed in an approved raceway or by other approved means.
  4. Service Conductors. Service conductors shall be permit‐ ted to be protected by overcurrent devices in accordance with 230.91.
  5. Busway Taps. Busways and busway taps shall be permitted to be protected against overcurrent in accordance with 368.17.
  6. Motor Circuit Taps. Motor-feeder and branch-circuit conductors shall be permitted to be protected against overcur‐ rent in accordance with 430.28 and 430.53, respectively.
  7. Conductors from Generator Terminals. Conductors from generator terminals that meet the size requirement in 445.13 shall be permitted to be protected against overload by the generator overload protective device(s) required by 445.12.
  8. Battery Conductors. Overcurrent protection shall be permitted to be installed as close as practicable to the storage battery terminals in an unclassified location. Installation of the overcurrent protection within a hazardous (classified) location shall also be permitted.
  1. Grounded Conductor. No overcurrent device shall be connected in series with any conductor that is intentionally grounded, unless one of the following two conditions is met:
    1. The overcurrent device opens all conductors of the circuit, including the grounded conductor, and is designed so that no pole can operate independently.
    2. Where required by 430.36 or 430.37 for motor overload protection.
  2. Change in Size of Grounded Conductor. Where a change occurs in the size of the ungrounded conductor, a simi‐ lar change shall be permitted to be made in the size of the grounded conductor.
  3. Location in or on Premises.
  1. Accessibility. Switches containing fuses and circuit break‐ ers shall be readily accessible and installed so that the center of the grip of the operating handle of the switch or circuit breaker, when in its highest position, is not more than 2.0 m (6 ft 7 in.) above the floor or working platform, unless one of the following applies:
    1. For busways, as provided in 368.17(C).
    2. For supplementary overcurrent protection, as described in 240.10.
    3. For overcurrent devices, as described in 225.40 and 230.92.
    4. For overcurrent devices adjacent to utilization equipment that they supply, access shall be permitted to be by porta‐ ble means.

    Exception: The use of a tool shall be permitted to access overcurrentdevices located within listed industrial control panels or similar enclo‐ sures.
  2. Occupancy. Each occupant shall have ready access to all overcurrent devices protecting the conductors supplying that occupancy, unless otherwise permitted in 240.24(B)(1) and (B)(2).
    1. Service and Feeder Overcurrent Devices. Where electric service and electrical maintenance are provided by the build‐ ing management and where these are under continuous build‐ ing management supervision, the service overcurrent devices and feeder overcurrent devices supplying more than one occu‐ pancy shall be permitted to be accessible only to authorized management personnel in the following:
      1. Multiple-occupancy buildings
      2. Guest rooms or guest suites
      3. Branch-Circuit Overcurrent Devices. Where electric serv‐ ice and electrical maintenance are provided by the building management and where these are under continuous building management supervision, the branch-circuit overcurrent devi‐ ces supplying any guest rooms or guest suites without perma‐ nent provisions for cooking shall be permitted to be accessible only to authorized management personnel.
  3. Not Exposed to Physical Damage. Overcurrent devices shall be located where they will not be exposed to physical damage.Informational Note: See 110.11, Deteriorating Agents.
  4. Not in Vicinity of Easily Ignitible Material. Overcurrent devices shall not be located in the vicinity of easily ignitible material, such as in clothes closets.
  5. Not Located in Bathrooms. In dwelling units, dormitories, and guest rooms or guest suites, overcurrent devices, other than supplementary overcurrent protection, shall not be loca‐ ted in bathrooms.
  6. Not Located over Steps. Overcurrent devices shall not be located over steps of a stairway.

Part III. Enclosures

240.30 General.

  1. Protection from Physical Damage. Overcurrent devices shall be protected from physical damage by one of the follow‐ ing:
    1. Installation in enclosures, cabinets, cutout boxes, or equipment assemblies
    2. Mounting on open-type switchboards, panelboards, or control boards that are in rooms or enclosures free from dampness and easily ignitible material and are accessible only to qualified personnel
  2. Operating Handle. The operating handle of a circuit breaker shall be permitted to be accessible without opening a door or cover.
  1. Damp or Wet Locations. Enclosures for overcurrent devices in damp or wet locations shall comply with 312.2.
  2. Vertical Position. Enclosures for overcurrent devices shall be mounted in a vertical position unless that is shown to be impracticable. Circuit breaker enclosures shall be permitted to be installed horizontally where the circuit breaker is instal‐ led in accordance with 240.81. Listed busway plug-in units shall be permitted to be mounted in orientations corresponding to the busway mounting position.

Part IV. Disconnecting and Guarding

  1. Disconnecting Means for Fuses. Cartridge fuses in circuits of any voltage where accessible to other than qualified persons, and all fuses in circuits over 150 volts to ground, shall be provided with a disconnecting means on their supply side so that each circuit containing fuses can be independently discon‐ nected from the source of power. A current-limiting device without a disconnecting means shall be permitted on the supply side of the service disconnecting means as permitted by230.82. A single disconnecting means shall be permitted on the supply side of more than one set of fuses as permitted by 430.112, Exception, for group operation of motors and 424.22(C) for fixed electric space-heating equipment.
  2. Arcing or Suddenly Moving Parts. Arcing or suddenly moving parts shall comply with 240.41(A) and (B).
  1. Location. Fuses and circuit breakers shall be located or shielded so that persons will not be burned or otherwise injured by their operation.
  2. Suddenly Moving Parts. Handles or levers of circuit breakers, and similar parts that may move suddenly in such a way that persons in the vicinity are likely to be injured by being struck by them, shall be guarded or isolated.

Part V. Plug Fuses, Fuseholders, and Adapters

  1. General.
    1. Maximum Voltage. Plug fuses shall be permitted to be used in the following circuits:
      1. Circuits not exceeding 125 volts between conductors
      2. Circuits supplied by a system having a grounded neutral point where the line-to-neutral voltage does not exceed 150 volts
    2. Marking. Each fuse, fuseholder, and adapter shall be marked with its ampere rating.
    3. Hexagonal Configuration. Plug fuses of 15-ampere and lower rating shall be identified by a hexagonal configuration of the window, cap, or other prominent part to distinguish them from fuses of higher ampere ratings.
    4. No Energized Parts. Plug fuses, fuseholders, and adapters shall have no exposed energized parts after fuses or fuses and adapters have been installed.
    5. Screw Shell. The screw shell of a plug-type fuseholder shall be connected to the load side of the circuit.
  2. Edison-Base Fuses.
    1. Classification. Plug fuses of the Edison-base type shall be classified at not over 125 volts and 30 amperes and below.
    2. Replacement Only. Plug fuses of the Edison-base type shall be used only for replacements in existing installations where there is no evidence of overfusing or tampering.
  3. Edison-Base Fuseholders. Fuseholders of the Edison- base type shall be installed only where they are made to accept Type S fuses by the use of adapters.
  4. Type S Fuses. Type S fuses shall be of the plug type and shall comply with 240.53(A) and (B).
    1. Classification. Type S fuses shall be classified at not over 125 volts and 0 to 15 amperes, 16 to 20 amperes, and 21 to 30 amperes.
    2. Noninterchangeable. Type S fuses of an ampere classifica‐ tion as specified in 240.53(A) shall not be interchangeable with a lower ampere classification. They shall be designed so that they cannot be used in any fuseholder other than a Type S fuse‐ holder or a fuseholder with a Type S adapter inserted.
  5. Type S Fuses, Adapters, and Fuseholders.
  1. To Fit Edison-Base Fuseholders. Type S adapters shall fit Edison-base fuseholders.
  2. To Fit Type S Fuses Only. Type S fuseholders and adapt‐ ers shall be designed so that either the fuseholder itself or the fuseholder with a Type S adapter inserted cannot be used for any fuse other than a Type S fuse.
  3. Nonremovable. Type S adapters shall be designed so that once inserted in a fuseholder, they cannot be removed.
  4. Nontamperable. Type S fuses, fuseholders, and adapters shall be designed so that tampering or shunting (bridging) would be difficult.
  5. Interchangeability. Dimensions of Type S fuses, fusehold‐ ers, and adapters shall be standardized to permit interchangea‐ bility regardless of the manufacturer.

Part VI. Cartridge Fuses and Fuseholders

  1. General.
    1. Maximum Voltage — 300-Volt Type. Cartridge fuses and fuseholders of the 300-volt type shall be permitted to be used in the following circuits:
      1. Circuits not exceeding 300 volts between conductors
      2. Single-phase line-to-neutral circuits supplied from a 3-phase, 4-wire, solidly grounded neutral source where the line-to-neutral voltage does not exceed 300 volts
    2. Noninterchangeable — 0–6000-Ampere Cartridge Fuse‐ holders. Fuseholders shall be designed so that it will be diffi‐ cult to put a fuse of any given class into a fuseholder that is designed for a current lower, or voltage higher, than that of the class to which the fuse belongs. Fuseholders for current- limiting fuses shall not permit insertion of fuses that are not current-limiting.
    3. Marking. Fuses shall be plainly marked, either by printing on the fuse barrel or by a label attached to the barrel showing the following:
      1. Ampere rating
      2. Voltage rating
      3. Interrupting rating where other than 10,000 amperes
      4. Current limiting where applicable
      5. The name or trademark of the manufacturer
      The interrupting rating shall not be required to be marked on fuses used for supplementary protection.
    4. Renewable Fuses. Class H cartridge fuses of the renewa‐ ble type shall be permitted to be used only for replacement in existing installations where there is no evidence of overfusing or tampering.
  2. Classification. Cartridge fuses and fuseholders shall be classified according to voltage and amperage ranges. Fuses rated 1000 volts, nominal, or less shall be permitted to be used for voltages at or below their ratings.
image

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240.67 Arc Energy Reduction. Where fuses rated 1200 A or higher are installed, 240.67(A) and (B) shall apply. This requirement shall become effective January 1, 2020.

  1. Documentation. Documentation shall be available to those authorized to design, install, operate, or inspect the installation as to the location of the fuses.
  2. Method to Reduce Clearing Time. A fuse shall have a clearing time of 0.07 seconds or less at the available arcing current, or one of the following shall be provided:
  1. Differential relaying
  2. Energy-reducing maintenance switching with local status indicator
  3. Energy-reducing active arc flash mitigation system
  4. An approved equivalent means

Informational Note No. 1: An energy-reducing maintenance switch allows a worker to set a disconnect switch to reduce the clearing time while the worker is working within an arc-flash boundary as defined in NFPA 70E -2015, Standard for Electrical Safety in the Workplace, and then to set the disconnect switch back to a normal setting after the potentially hazardous work is complete.

Informational Note No. 2: An energy-reducing active arc flash mitigation system helps in reducing arcing duration in the elec‐ trical distribution system. No change in the disconnect switch or the settings of other devices is required during maintenance when a worker is working within an arc flash boundary as defined in NFPA 70E -2015, Standard for Electrical Safety in the Workplace.

Informational Note No. 3: IEEE 1584, IEEE Guide for Performing Arc Flash Hazard Calculations, is one of the available methods that provides guidance in determining arcing current.

Part VII. Circuit Breakers

  1. Method of Operation. Circuit breakers shall be trip free and capable of being closed and opened by manual opera‐ tion. Their normal method of operation by other than manual means, such as electrical or pneumatic, shall be permitted if means for manual operation are also provided.
  2. Indicating. Circuit breakers shall clearly indicate whether they are in the open “off” or closed “on” position.Where circuit breaker handles are operated vertically rather than rotationally or horizontally, the “up” position of the handle shall be the “on” position.
  3. Nontamperable. A circuit breaker shall be of such design that any alteration of its trip point (calibration) or the time required for its operation requires dismantling of the device or breaking of a seal for other than intended adjust‐ ments.
  4. Marking.
  1. Durable and Visible. Circuit breakers shall be marked with their ampere rating in a manner that will be durable and visible after installation. Such marking shall be permitted to be made visible by removal of a trim or cover.
  2. Location. Circuit breakers rated at 100 amperes or less and 1000 volts or less shall have the ampere rating molded, stamped, etched, or similarly marked into their handles or escutcheon areas.
  3. Interrupting Rating. Every circuit breaker having an inter‐ rupting rating other than 5000 amperes shall have its interrupt‐ ing rating shown on the circuit breaker. The interrupting rating shall not be required to be marked on circuit breakers used for supplementary protection.
  4. Used as Switches. Circuit breakers used as switches in 120-volt and 277-volt fluorescent lighting circuits shall be listed and shall be marked SWD or HID. Circuit breakers used as switches in high-intensity discharge lighting circuits shall be listed and shall be marked as HID.
  5. Voltage Marking. Circuit breakers shall be marked with a voltage rating not less than the nominal system voltage that is

indicative of their capability to interrupt fault currents between phases or phase to ground.

  1. Applications. A circuit breaker with a straight voltage rating, such as 240V or 480V, shall be permitted to be applied in a circuit in which the nominal voltage between any two conductors does not exceed the circuit breaker’s voltage rating. A two-pole circuit breaker shall not be used for protecting a 3-phase, corner-grounded delta circuit unless the circuit breaker is marked 1φ–3φ to indicate such suitability.A circuit breaker with a slash rating, such as 120/240V or 480Y/277V, shall be permitted to be applied in a solidly groun‐ ded circuit where the nominal voltage of any conductor to ground does not exceed the lower of the two values of the circuit breaker’s voltage rating and the nominal voltage between any two conductors does not exceed the higher value of the circuit breaker’s voltage rating.Informational Note: Proper application of molded case circuit breakers on 3-phase systems, other than solidly grounded wye, particularly on corner grounded delta systems, considers the circuit breakers’ individual pole-interrupting capability.
  2. Series Ratings. Where a circuit breaker is used on a circuit having an available fault current higher than the marked interrupting rating by being connected on the load side of an acceptable overcurrent protective device having a higher rating, the circuit breaker shall meet the requirements specified in (A) or (B), and (C).
    1. Selected Under Engineering Supervision in Existing Instal‐ lations. The series rated combination devices shall be selected by a licensed professional engineer engaged primarily in the design or maintenance of electrical installations. The selection shall be documented and stamped by the professional engi‐ neer. This documentation shall be available to those authorized to design, install, inspect, maintain, and operate the system. This series combination rating, including identification of the upstream device, shall be field marked on the end use equip‐ ment.For calculated applications, the engineer shall ensure that the downstream circuit breaker(s) that are part of the series combination remain passive during the interruption period of the line side fully rated, current-limiting device.
    2. Tested Combinations. The combination of line-side over‐ current device and load-side circuit breaker(s) is tested and marked on the end use equipment, such as switchboards and panelboards.Informational Note to (A) and (B): See 110.22 for marking of series combination systems.
    3. Motor Contribution. Series ratings shall not be used where
    1. Motors are connected on the load side of the higher- rated overcurrent device and on the line side of the lower-rated overcurrent device, and
    2. The sum of the motor full-load currents exceeds 1 percent of the interrupting rating of the lower-rated circuit breaker.
  3. Arc Energy Reduction. Where the highest continuous current trip setting for which the actual overcurrent device installed in a circuit breaker is rated or can be adjusted is 1200 A or higher, 240.87(A) and (B) shall apply.
  1. Documentation. Documentation shall be available to those authorized to design, install, operate, or inspect the installation as to the location of the circuit breaker(s).
  2. Method to Reduce Clearing Time. One of the following means shall be provided:
  1. Zone-selective interlocking
  2. Differential relaying
  3. Energy-reducing maintenance switching with local status indicator
  4. Energy-reducing active arc flash mitigation system
  1. An instantaneous trip setting that is less than the availablearcing current
  2. An instantaneous override that is less than the available arcing current
  3. An approved equivalent means

Informational Note No. 1: An energy-reducing maintenance switch allows a worker to set a circuit breaker trip unit to “no intentional delay” to reduce the clearing time while the worker is working within an arc-flash boundary as defined in NFPA 70E

-2015, Standard for Electrical Safety in the Workplace, and then to set the trip unit back to a normal setting after the potentially hazardous work is complete.

Informational Note No. 2: An energy-reducing active arc flash mitigation system helps in reducing arcing duration in the elec‐ trical distribution system. No change in the circuit breaker or the settings of other devices is required during maintenance when a worker is working within an arc flash boundary as defined in NFPA 70E -2015, Standard for Electrical Safety in the Workplace.

Informational Note No. 3: An instantaneous trip is a function

that causes a circuit breaker to trip with no intentional delay when currents exceed the instantaneous trip setting or current level. If arcing currents are above the instantaneous trip level, the circuit breaker will trip in the minimum possible time.

Informational Note No. 4: IEEE 1584–2002, IEEE Guide for Performing Arc Flash Hazard Calculations, is one of the available methods that provide guidance in determining arcing current.

Part VIII. Supervised Industrial Installations

  1. General. Overcurrent protection in areas of super‐ vised industrial installations shall comply with all of the other applicable provisions of this article, except as provided in Part VIII. The provisions of Part VIII shall be permitted to apply only to those portions of the electrical system in the supervised industrial installation used exclusively for manufac‐ turing or process control activities.
  2. Protection of Conductors. Conductors shall be protec‐ ted in accordance with 240.91(A) or 240.91(B)
    1. General. Conductors shall be protected in accordance with 240.4.
    2. Devices Rated Over 800 Amperes. Where the overcurrent device is rated over 800 amperes, the ampacity of the conduc‐ tors it protects shall be equal to or greater than 95 percent of the rating of the overcurrent device specified in 240.6 in accordance with (B)(1) and (2).
    1. The conductors are protected within recognized time vs. current limits for short-circuit currents
    2. All equipment in which the conductors terminate is listed and marked for the application
  3. Location in Circuit. An overcurrent device shall be connected in each ungrounded circuit conductor as required in 240.92(A) through (E).
  1. Feeder and Branch-Circuit Conductors. Feeder and branch-circuit conductors shall be protected at the point the conductors receive their supply as permitted in 240.21 or as otherwise permitted in 240.92(B), (C), (D), or (E).
  2. Feeder Taps. For feeder taps specified in 240.21(B)(2), (B)(3), and (B)(4), the tap conductors shall be permitted to be sized in accordance with Table 240.92(B).
  3. Transformer Secondary Conductors of Separately Derived Systems. Conductors shall be permitted to be connected to a transformer secondary of a separately derived system, without overcurrent protection at the connection, where the conditions of 240.92(C)(1), (C)(2), and (C)(3) are met.
    1. Short-Circuit and Ground-Fault Protection. The conduc‐ tors shall be protected from short-circuit and ground-fault conditions by complying with one of the following conditions:
      1. The length of the secondary conductors does not exceed 30 m (100 ft), and the transformer primary overcurrent device has a rating or setting that does not exceed 150 percent of the value determined by multiplying the secondary conductor ampacity by the secondary-to- primary transformer voltage ratio.
      2. The conductors are protected by a differential relay with a trip setting equal to or less than the conductor ampac‐ ity.

      Table 240.92(B) Tap Conductor Short-Circuit Current Ratings
      imageTap conductors are considered to be protected under short-circuit conditions when their short-circuit temperature limit is not exceeded. Conductor heating under short-circuit conditions is determined by (1) or (2):
      1. Short-Circuit Formula for Copper Conductors(I 2/A 2)t = 0.0297 log10 [(T 2 + 234)/(T 1 + 234)]
      2. Short-Circuit Formula for Aluminum Conductors(I 2/A 2)t = 0.0125 log10 [(T 2 + 228)/(T 1 + 228)]where:I = short-circuit current in amperesA = conductor area in circular milst = time of short circuit in seconds (for times less than or equal to 10 seconds)T 1 = initial conductor temperature in degrees CelsiusT 2 = final conductor temperature in degrees CelsiusCopper conductor with paper, rubber, varnished cloth insulation,T 2 = 200Copper conductor with thermoplastic insulation, T 2 = 150 Copper conductor with cross-linked polyethylene insulation,T 2 = 250Copper conductor with ethylene propylene rubber insulation,T 2 = 250Aluminum conductor with paper, rubber, varnished cloth insulation, T 2 = 200Aluminum conductor with thermoplastic insulation, T 2 = 150 Aluminum conductor with cross-linked polyethylene insulation,T 2 = 250Aluminum conductor with ethylene propylene rubber insulation,   T 2 = 250                                                                                                               Informational Note: A differential relay is connected to be sensi‐ tive only to short-circuit or fault currents within the protected zone and is normally set much lower than the conductor ampac‐ ity. The differential relay is connected to trip protective devices that de-energize the protected conductors if a short-circuit condition occurs.
      3. The conductors shall be considered to be protected if calculations, made under engineering supervision, deter‐ mine that the system overcurrent devices will protect the conductors within recognized time vs. current limits for all short-circuit and ground-fault conditions.
      (2) Overload Protection. The conductors shall be protected against overload conditions by complying with one of the following:
      1. The conductors terminate in a single overcurrent device that will limit the load to the conductor ampacity.
      2. The sum of the overcurrent devices at the conductor termination limits the load to the conductor ampacity. The overcurrent devices shall consist of not more than six circuit breakers or sets of fuses mounted in a single enclo‐ sure, in a group of separate enclosures, or in or on a switchboard or switchgear. There shall be no more than six overcurrent devices grouped in any one location.
      3. Overcurrent relaying is connected [with a current trans‐ former(s), if needed] to sense all of the secondary conductor current and limit the load to the conductor ampacity by opening upstream or downstream devices.
      4. Conductors shall be considered to be protected if calcula‐ tions, made under engineering supervision, determine that the system overcurrent devices will protect the conductors from overload conditions.
      (3) Physical Protection. The secondary conductors are protec‐ ted from physical damage by being enclosed in an approved raceway or by other approved means.
  4. Outside Feeder Taps. Outside conductors shall be permitted to be tapped to a feeder or to be connected at a transformer secondary, without overcurrent protection at the tap or connection, where all the following conditions are met:
    1. The conductors are protected from physical damage in an approved manner.
    2. The sum of the overcurrent devices at the conductor termination limits the load to the conductor ampacity. The overcurrent devices shall consist of not more than six circuit breakers or sets of fuses mounted in a single enclo‐ sure, in a group of separate enclosures, or in or on a switchboard or switchgear. There shall be no more than six overcurrent devices grouped in any one location.
    3. The tap conductors are installed outdoors of a building or structure except at the point of load termination.
    4. The overcurrent device for the conductors is an integral part of a disconnecting means or is located immediately adjacent thereto.
    5. The disconnecting means for the conductors are installed at a readily accessible location complying with one of the following:
      1. Outside of a building or structure
      2. Inside, nearest the point of entrance of the conduc‐ tors
      3. Where installed in accordance with 230.6, nearest the point of entrance of the conductors
  5. Protection by Primary Overcurrent Device. Conductors supplied by the secondary side of a transformer shall be permit‐ ted to be protected by overcurrent protection provided on the primary (supply) side of the transformer, provided the primary device time–current protection characteristic, multiplied by the maximum effective primary-to-secondary transformer voltage ratio, effectively protects the secondary conductors.

Part IX. Overcurrent Protection over 1000 Volts, Nominal

  1. Feeders and Branch Circuits.
    1. Location and Type of Protection. Feeder and branch- circuit conductors shall have overcurrent protection in each ungrounded conductor located at the point where the conduc‐ tor receives its supply or at an alternative location in the circuit when designed under engineering supervision that includes but is not limited to considering the appropriate fault studies and time–current coordination analysis of the protective devi‐ ces and the conductor damage curves. The overcurrent protec‐ tion shall be permitted to be provided by either 240.100(A)(1) or (A)(2).
      1. Overcurrent Relays and Current Transformers. Circuit breakers used for overcurrent protection of 3-phase circuits shall have a minimum of three overcurrent relay elements operated from three current transformers. The separate over‐ current relay elements (or protective functions) shall be permitted to be part of a single electronic protective relay unit.On 3-phase, 3-wire circuits, an overcurrent relay element in the residual circuit of the current transformers shall be permit‐ ted to replace one of the phase relay elements.An overcurrent relay element, operated from a current transformer that links all phases of a 3-phase, 3-wire circuit, shall be permitted to replace the residual relay element and one of the phase-conductor current transformers. Where the neutral conductor is not regrounded on the load side of the circuit as permitted in 250.184(B), the current transformer shall be permitted to link all 3-phase conductors and the grounded circuit conductor (neutral).
      2. Fuses. A fuse shall be connected in series with each ungrounded conductor.
    2. Protective Devices. The protective device(s) shall be capa‐ ble of detecting and interrupting all values of current that can occur at their location in excess of their trip-setting or melting point.
    3. Conductor Protection. The operating time of the protec‐ tive device, the available short-circuit current, and the conduc‐ tor used shall be coordinated to prevent damaging or dangerous temperatures in conductors or conductor insulation under short-circuit conditions.
  2. Additional Requirements for Feeders.
  1. Rating or Setting of Overcurrent Protective Devices. The continuous ampere rating of a fuse shall not exceed three times the ampacity of the conductors. The long-time trip element setting of a breaker or the minimum trip setting of an electronically actuated fuse shall not exceed six times the ampacity of the conductor. For fire pumps, conductors shall be permitted to be protected for overcurrent in accordance with 695.4(B)(2).
  2. Feeder Taps. Conductors tapped to a feeder shall be permitted to be protected by the feeder overcurrent device where that overcurrent device also protects the tap conductor.

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