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Chapter 2 Wiring and Protection
|
250.162(B)
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The neutral conductor of all 3-wire, dc systems supplying premises wiring shall be grounded. [250.162(B)](https://2023.antflix.net#250.162(B))
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https://2023.antflix.net#250.162(B)
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Chapter 2 Wiring and Protection
|
250.164(A)
|
Direct-current systems to be grounded and supplied from an off-premises source shall have the grounding connection made at one or more supply stations. A grounding connection shall not be made at individual services or at any point on the premises wiring. [250.164(A)](https://2023.antflix.net#250.164(A))
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https://2023.antflix.net#250.164(A)
|
Chapter 2 Wiring and Protection
|
250.164(B)
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If the dc system source is located on the premises, a grounding connection shall be made at one of the following: The sourceThe first system disconnection means or overcurrent deviceBy other means that accomplish system protection and that use equipment listed and identified for the use [250.164(B)](https://2023.antflix.net#250.164(B))
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https://2023.antflix.net#250.164(B)
|
Chapter 2 Wiring and Protection
|
250.166
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The size of the grounding electrode conductor for a dc system shall be as specified in 250.166(A) and (B), except as permitted by 250.166(C) through (E). The grounding electrode conductor for a dc system shall meet the sizing requirements in this section but shall not be required to be larger than 3/0 copper or 250 kcmil aluminum or copper-clad aluminum. [250.166](https://2023.antflix.net#250.166)
|
https://2023.antflix.net#250.166
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Chapter 2 Wiring and Protection
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250.166(A)
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If the dc system consists of a 3-wire balancer set or a balancer winding with overcurrent protection as provided in 445.12(D), the grounding electrode conductor shall not be smaller than the neutral conductor and not smaller than 8 AWG copper or 6 AWG aluminum or copper-clad aluminum. [250.166(A)](https://2023.antflix.net#250.166(A))
|
https://2023.antflix.net#250.166(A)
|
Chapter 2 Wiring and Protection
|
250.166(B)
|
If the dc system is other than as in 250.166(A), the grounding electrode conductor shall not be smaller than the largest conductor supplied by the system and not smaller than 8 AWG copper or 6 AWG aluminum or copper-clad aluminum. [250.166(B)](https://2023.antflix.net#250.166(B))
|
https://2023.antflix.net#250.166(B)
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Chapter 2 Wiring and Protection
|
250.166(C)
|
If connected to rod, pipe, or plate electrodes as in 250.52(A)(5) or (A)(7), that portion of the grounding electrode conductor that is the sole connection to the grounding electrode shall not be required to be larger than 6 AWG copper wire or 4 AWG aluminum or copper-clad aluminum wire. [250.166(C)](https://2023.antflix.net#250.166(C))
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https://2023.antflix.net#250.166(C)
|
Chapter 2 Wiring and Protection
|
250.166(D)
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If connected to a concrete-encased electrode as in 250.52(A)(3), that portion of the grounding electrode conductor that is the sole connection to the grounding electrode shall not be required to be larger than 4 AWG copper wire. [250.166(D)](https://2023.antflix.net#250.166(D))
|
https://2023.antflix.net#250.166(D)
|
Chapter 2 Wiring and Protection
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250.166(E)
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If connected to a ground ring as in 250.52(A)(4), that portion of the grounding electrode conductor that is the sole connection to the grounding electrode shall not be required to be larger than the conductor used for the ground ring. [250.166(E)](https://2023.antflix.net#250.166(E))
|
https://2023.antflix.net#250.166(E)
|
Chapter 2 Wiring and Protection
|
250.167(A)
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Ground-fault detection systems shall be required for ungrounded systems. [250.167(A)](https://2023.antflix.net#250.167(A))
|
https://2023.antflix.net#250.167(A)
|
Chapter 2 Wiring and Protection
|
250.167(B)
|
Ground-fault detection shall be permitted for grounded systems. [250.167(B)](https://2023.antflix.net#250.167(B))
|
https://2023.antflix.net#250.167(B)
|
Chapter 2 Wiring and Protection
|
250.167(C)
|
Direct-current systems shall be legibly marked to indicate the grounding type at the dc source or the first disconnecting means of the system. The marking shall be of sufficient durability to withstand the environment involved. Informational Note: See NFPA 70E-2018, Standard for Electrical Safety in the Workplace, which identifies four dc grounding types in detail. [250.167(C)](https://2023.antflix.net#250.167(C))
|
https://2023.antflix.net#250.167(C)
|
Chapter 2 Wiring and Protection
|
250.168
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For direct-current systems that are to be grounded, an unspliced bonding jumper shall be used to connect the equipment grounding conductor(s) to the grounded conductor at the source or to the first system disconnecting means where the system is grounded. The size of the bonding jumper shall not be smaller than the system grounding electrode conductor specified in 250.166 and shall comply with 250.28(A), (B), and (C). [250.168](https://2023.antflix.net#250.168)
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https://2023.antflix.net#250.168
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Chapter 2 Wiring and Protection
|
250.169
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Except as otherwise permitted in 250.34 for portable and vehicle-mounted generators, an ungrounded dc separately derived system supplied from a stand-alone power source (such as an engine-generator set) shall have a grounding electrode conductor connected to an electrode that complies with Part III of this article to provide for grounding of metal enclosures, raceways, cables, and exposed non-current-carrying metal parts of equipment. The grounding electrode conductor connection shall be to the metal enclosure at any point on the separately derived system from the source to the first system disconnecting means or overcurrent device, or it shall be made at the source of a separately derived system that has no disconnecting means or overcurrent devices. The size of the grounding electrode conductor shall be in accordance with 250.166. [250.169](https://2023.antflix.net#250.169)
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https://2023.antflix.net#250.169
|
Chapter 2 Wiring and Protection
|
250.170
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Secondary circuits of current and potential instrument transformers shall be grounded if the primary windings are connected to circuits of 300 volts or more to ground and, if installed on or in switchgear and on switchboards, shall be grounded irrespective of voltage. Exception No. 1: Circuits where the primary windings are connected to circuits of 1000 volts or less with no live parts or wiring exposed or accessible to other than qualified persons. Exception No. 2: Current transformer secondaries connected in a three-phase delta configuration shall not be required to be grounded. [250.170](https://2023.antflix.net#250.170)
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https://2023.antflix.net#250.170
|
Chapter 2 Wiring and Protection
|
250.172
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Cases or frames of instrument transformers shall be connected to the equipment grounding conductor if accessible to other than qualified persons. Exception: Cases or frames of current transformers, the primaries of which are not over 150 volts to ground and that are used exclusively to supply current to meters. [250.172](https://2023.antflix.net#250.172)
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https://2023.antflix.net#250.172
|
Chapter 2 Wiring and Protection
|
250.174
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Instruments, meters, and relays operating with windings or working parts at 1000 volts or less shall be connected to the equipment grounding conductor as specified in 250.174(A), (B), or (C). [250.174](https://2023.antflix.net#250.174)
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https://2023.antflix.net#250.174
|
Chapter 2 Wiring and Protection
|
250.174(A)
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Instruments, meters, and relays not located on switchgear or switchboards operating with windings or working parts at 300 volts or more to ground, and accessible to other than qualified persons, shall have the cases and other exposed metal parts connected to the equipment grounding conductor. [250.174(A)](https://2023.antflix.net#250.174(A))
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https://2023.antflix.net#250.174(A)
|
Chapter 2 Wiring and Protection
|
250.174(B)
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Instruments, meters, and relays (whether operated from current and potential transformers or connected directly in the circuit) on switchgear or switchboards having no live parts on the front of the panels shall have the cases connected to the equipment grounding conductor. [250.174(B)](https://2023.antflix.net#250.174(B))
|
https://2023.antflix.net#250.174(B)
|
Chapter 2 Wiring and Protection
|
250.174(C)
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Instruments, meters, and relays (whether operated from current and potential transformers or connected directly in the circuit) on switchboards having exposed live parts on the front of panels shall not have their cases connected to the equipment grounding conductor. Mats of insulating rubber or other approved means of floor insulation shall be provided for the operator where the voltage to ground exceeds 150 volts. [250.174(C)](https://2023.antflix.net#250.174(C))
|
https://2023.antflix.net#250.174(C)
|
Chapter 2 Wiring and Protection
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250.176
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If instruments, meters, and relays have current-carrying parts of over 1000 volts to ground, they shall be isolated by elevation or protected by a barrier(s), grounded metal, or insulating covers or guards. Their cases shall not be connected to the equipment grounding conductor. Exception: Cases of electrostatic ground detectors shall be permitted to be connected to an equipment grounding conductor if the internal ground segments of the instrument are connected to the instrument case and grounded and the ground detector is isolated by elevation. [250.176](https://2023.antflix.net#250.176)
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https://2023.antflix.net#250.176
|
Chapter 2 Wiring and Protection
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250.178
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The equipment grounding conductor for secondary circuits of instrument transformers and for instrument cases shall not be smaller than 12 AWG copper or 10 AWG aluminum or copper-clad aluminum. Cases of instrument transformers, instruments, meters, and relays that are mounted directly on grounded metal surfaces of enclosures or grounded metal of switchgear or switchboard panels shall not be required to be connected to an additional equipment grounding conductor. [250.178](https://2023.antflix.net#250.178)
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https://2023.antflix.net#250.178
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Chapter 2 Wiring and Protection
|
250.180
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If systems over 1000 volts are grounded, they shall comply with all applicable requirements of 250.1 through 250.178 and with 250.182 through 250.194, which supplement and modify the preceding sections. [250.180](https://2023.antflix.net#250.180)
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https://2023.antflix.net#250.180
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Chapter 2 Wiring and Protection
|
250.182
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A system neutral point derived from a grounding transformer shall be permitted to be used for grounding systems over 1 kV. [250.182](https://2023.antflix.net#250.182)
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https://2023.antflix.net#250.182
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Chapter 2 Wiring and Protection
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250.184
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Solidly grounded neutral systems shall be permitted to be either single point grounded or multigrounded neutral. [250.184](https://2023.antflix.net#250.184)
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https://2023.antflix.net#250.184
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Chapter 2 Wiring and Protection
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250.184(A)(1)
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The minimum insulation level for neutral conductors of solidly grounded systems shall be 600 volts. Exception No. 1: For multigrounded neutral systems as permitted in 250.184(C), bare copper conductors shall be permitted to be used for the neutral conductor of the following: (1) Service-entrance conductors (2) Service laterals or underground service conductors (3) Direct-buried portions of feeders Exception No. 2: Bare conductors shall be permitted for the neutral conductor of overhead portions installed outdoors. Exception No. 3: The grounded neutral conductor shall be permitted to be a bare conductor if isolated from phase conductors and protected from physical damage. Informational Note: See 225.4 for conductor covering where within 3.0 m (10 ft) of any building or other structure. [250.184(A)(1)](https://2023.antflix.net#250.184(A)(1))
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https://2023.antflix.net#250.184(A)(1)
|
Chapter 2 Wiring and Protection
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250.184(A)(2)
|
The neutral conductor shall have an ampacity that is not less than the load imposed and be not less than 331/3 percent of the ampacity of the phase conductors. Exception: In industrial and commercial premises under engineering supervision, it shall be permissible to size the ampacity of the neutral conductor to not less than 20 percent of the ampacity of the phase conductor. [250.184(A)(2)](https://2023.antflix.net#250.184(A)(2))
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https://2023.antflix.net#250.184(A)(2)
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Chapter 2 Wiring and Protection
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250.184(B)
|
If a single-point grounded neutral system is used, the following shall apply: A single-point grounded neutral system shall be permitted to be supplied from one of the following:A separately derived systemA multigrounded neutral system with an equipment grounding conductor connected to the multigrounded neutral conductor at the source of the single-point grounded neutral systemA grounding electrode shall be provided for the system.A grounding electrode conductor shall connect the grounding electrode to the system neutral conductor.A bonding jumper shall connect the equipment grounding conductor to the grounding electrode conductor.An equipment grounding conductor shall be provided to each building, structure, and equipment enclosure.A neutral conductor shall only be required if phase-to-neutral loads are supplied.The neutral conductor, if provided, shall be insulated and isolated from earth except at one location.An equipment grounding conductor shall be run with the phase conductors and shall comply with all of the following:Shall not carry continuous loadShall be bare, covered, or insulatedShall have ampacity for fault current duty [250.184(B)](https://2023.antflix.net#250.184(B))
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https://2023.antflix.net#250.184(B)
|
Chapter 2 Wiring and Protection
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250.184(C)
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If a multigrounded neutral system is used, the following shall apply: The neutral conductor of a solidly grounded neutral system shall be permitted to be grounded at more than one point. Grounding shall be permitted at one or more of the following locations:Transformers supplying conductors to a building or other structureUnderground circuits if the neutral conductor is exposedOverhead circuits installed outdoorsThe multigrounded neutral conductor shall be grounded at each transformer and at other additional locations by connection to a grounding electrode.At least one grounding electrode shall be installed and connected to the multigrounded neutral conductor every 400 m (1300 ft).The maximum distance between any two adjacent electrodes shall not be more than 400 m (1300 ft).In a multigrounded shielded cable system, the shielding shall be grounded at each cable joint that is exposed to personnel contact.Exception: In a multipoint grounded system, a grounding electrode shall not be required to bond the neutral conductor in an uninterrupted conductor exceeding 400 m (1300 ft) if the only purpose for removing the cable jacket is for bonding the neutral conductor to a grounding electrode. [250.184(C)](https://2023.antflix.net#250.184(C))
|
https://2023.antflix.net#250.184(C)
|
Chapter 2 Wiring and Protection
|
250.186(A)
|
If an ac system is grounded at any point and is provided with a grounded conductor at the service point, a grounded conductor(s) shall be installed and routed with the ungrounded conductors to each service disconnecting means and shall be connected to each disconnecting means grounded conductor(s) terminal or bus. A main bonding jumper shall connect the grounded conductor(s) to each service disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with 250.186(A)(1) through (A)(4). The size of the solidly grounded circuit conductor(s) shall be the larger of that determined by 250.184 or 250.186(A)(1) or (A)(2). Exception: If two or more service disconnecting means are located in a single assembly listed for use as service equipment, it shall be permitted to connect the grounded, conductor(s) to the assembly common grounded conductor(s) terminal or bus. The assembly shall include a main bonding jumper for connecting the grounded conductor(s) to the assembly enclosure. [250.186(A)](https://2023.antflix.net#250.186(A))
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https://2023.antflix.net#250.186(A)
|
Chapter 2 Wiring and Protection
|
250.186(A)(1)
|
The grounded conductor shall not be smaller than the required grounding electrode conductor specified in Table 250.102(C)(1) but shall not be required to be larger than the largest ungrounded service-entrance conductor(s). [250.186(A)(1)](https://2023.antflix.net#250.186(A)(1))
|
https://2023.antflix.net#250.186(A)(1)
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Chapter 2 Wiring and Protection
|
250.186(A)(2)
|
If the ungrounded service-entrance conductors are installed in parallel in two or more raceways or as overhead parallel conductors, the grounded conductors shall also be installed in parallel. The size of the grounded conductor in each raceway or overhead shall be based on the total circular mil area of the parallel ungrounded conductors in the raceway or overhead, as indicated in 250.186(A)(1), but not smaller than 1/0 AWG. Informational Note: See 310.10(G) for grounded conductors connected in parallel. [250.186(A)(2)](https://2023.antflix.net#250.186(A)(2))
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https://2023.antflix.net#250.186(A)(2)
|
Chapter 2 Wiring and Protection
|
250.186(A)(3)
|
The grounded conductor of a 3-phase, 3-wire delta service shall have an ampacity not less than that of the ungrounded conductors. [250.186(A)(3)](https://2023.antflix.net#250.186(A)(3))
|
https://2023.antflix.net#250.186(A)(3)
|
Chapter 2 Wiring and Protection
|
250.186(A)(4)
|
Impedance grounded systems shall be installed in accordance with 250.187. [250.186(A)(4)](https://2023.antflix.net#250.186(A)(4))
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https://2023.antflix.net#250.186(A)(4)
|
Chapter 2 Wiring and Protection
|
250.186(B)
|
If an ac system is grounded at any point and is not provided with a grounded conductor at the service point, a supply-side bonding jumper shall be installed and routed with the ungrounded conductors to each service disconnecting means and shall be connected to each disconnecting means equipment grounding conductor terminal or bus. The supply-side bonding jumper shall be installed in accordance with 250.186(B)(1) through (B)(3). Exception: If two or more service disconnecting means are located in a single assembly listed for use as service equipment, it shall be permitted to connect the supply-side bonding jumper to the assembly common equipment grounding terminal or bus. [250.186(B)](https://2023.antflix.net#250.186(B))
|
https://2023.antflix.net#250.186(B)
|
Chapter 2 Wiring and Protection
|
250.186(B)(1)
|
The supply-side bonding jumper shall not be smaller than the required grounding electrode conductor specified in Table 250.102(C)(1) but shall not be required to be larger than the largest ungrounded service-entrance conductor(s). [250.186(B)(1)](https://2023.antflix.net#250.186(B)(1))
|
https://2023.antflix.net#250.186(B)(1)
|
Chapter 2 Wiring and Protection
|
250.186(B)(2)
|
If the ungrounded service-entrance conductors are installed in parallel in two or more raceways or overhead conductors, the supply-side bonding jumper shall also be installed in parallel. The size of the supply-side bonding jumper in each raceway or overhead shall be based on the total circular mil area of the parallel ungrounded conductors in the raceway or overhead, as indicated in 250.186(A)(1), but not smaller than 1/0 AWG. [250.186(B)(2)](https://2023.antflix.net#250.186(B)(2))
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https://2023.antflix.net#250.186(B)(2)
|
Chapter 2 Wiring and Protection
|
250.186(B)(3)
|
Impedance grounded systems shall be installed in accordance with 250.187. [250.186(B)(3)](https://2023.antflix.net#250.186(B)(3))
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https://2023.antflix.net#250.186(B)(3)
|
Chapter 2 Wiring and Protection
|
250.187
|
Impedance grounded systems in which a grounding impedance device, typically a resistor, limits the ground-fault current shall be permitted if all of the following conditions are met: The conditions of maintenance and supervision ensure that only qualified persons service the installation.Ground detectors are installed on the system.Line-to-neutral loads are not served.Impedance grounded systems shall comply with 250.187(A) through (D). [250.187](https://2023.antflix.net#250.187)
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https://2023.antflix.net#250.187
|
Chapter 2 Wiring and Protection
|
250.187(A)
|
The grounding impedance device shall be installed between the grounding electrode conductor and the impedance grounding conductor connected to the system neutral point. [250.187(A)](https://2023.antflix.net#250.187(A))
|
https://2023.antflix.net#250.187(A)
|
Chapter 2 Wiring and Protection
|
250.187(B)
|
The impedance grounding conductor shall be insulated for the maximum neutral voltage. Exception: A bare impedance grounding conductor shall be permitted if the bare portion of the grounding impedance device and conductor are not in a readily accessible location and securely separated from the ungrounded conductors. Informational Note: The maximum neutral voltage in a 3-phase wye system is 57.7 percent of the phase-to-phase voltage. [250.187(B)](https://2023.antflix.net#250.187(B))
|
https://2023.antflix.net#250.187(B)
|
Chapter 2 Wiring and Protection
|
250.187(C)
|
The system neutral point shall not be connected to ground, except through the grounding impedance device. [250.187(C)](https://2023.antflix.net#250.187(C))
|
https://2023.antflix.net#250.187(C)
|
Chapter 2 Wiring and Protection
|
250.187(D)
|
Equipment grounding conductors shall be permitted to be bare and shall be electrically connected to the ground bus and grounding electrode conductor. [250.187(D)](https://2023.antflix.net#250.187(D))
|
https://2023.antflix.net#250.187(D)
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Chapter 2 Wiring and Protection
|
250.188
|
Systems supplying portable or mobile equipment over 1000 volts, other than substations installed on a temporary basis, shall comply with 250.188(A) through (F). [250.188](https://2023.antflix.net#250.188)
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https://2023.antflix.net#250.188
|
Chapter 2 Wiring and Protection
|
250.188(A)
|
Portable or mobile equipment over 1000 volts shall be supplied from a system having its neutral conductor grounded through an impedance. If a delta-connected system over 1000 volts is used to supply portable or mobile equipment, a system neutral point and associated neutral conductor shall be derived. [250.188(A)](https://2023.antflix.net#250.188(A))
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https://2023.antflix.net#250.188(A)
|
Chapter 2 Wiring and Protection
|
250.188(B)
|
Exposed noncurrent-carrying metal parts of portable or mobile equipment shall be connected by an equipment grounding conductor to the point at which the system neutral impedance is grounded. [250.188(B)](https://2023.antflix.net#250.188(B))
|
https://2023.antflix.net#250.188(B)
|
Chapter 2 Wiring and Protection
|
250.188(C)
|
The voltage developed between the portable or mobile equipment frame and ground by the flow of maximum ground-fault current shall not exceed 100 volts. [250.188(C)](https://2023.antflix.net#250.188(C))
|
https://2023.antflix.net#250.188(C)
|
Chapter 2 Wiring and Protection
|
250.188(D)
|
Ground-fault detection and relaying shall be provided to automatically de-energize any component of a system over 1000 volts that has developed a ground fault. The continuity of the equipment grounding conductor shall be continuously monitored so as to automatically de-energize the circuit of the system over 1000 volts to the portable or mobile equipment upon loss of continuity of the equipment grounding conductor. [250.188(D)](https://2023.antflix.net#250.188(D))
|
https://2023.antflix.net#250.188(D)
|
Chapter 2 Wiring and Protection
|
250.188(E)
|
The grounding electrode to which the portable or mobile equipment system neutral impedance is connected shall be isolated from and separated in the ground by at least 6.0 m (20 ft) from any other system or equipment grounding electrode, and there shall be no direct connection between the grounding electrodes, such as buried pipe and fence, and so forth. [250.188(E)](https://2023.antflix.net#250.188(E))
|
https://2023.antflix.net#250.188(E)
|
Chapter 2 Wiring and Protection
|
250.188(F)
|
Trailing cable and couplers of systems over 1000 volts for interconnection of portable or mobile equipment shall meet the requirements of Part III of Article 400 for cables and 495.65 for couplers. [250.188(F)](https://2023.antflix.net#250.188(F))
|
https://2023.antflix.net#250.188(F)
|
Chapter 2 Wiring and Protection
|
250.190(A)
|
All non-current-carrying metal parts of fixed, portable, and mobile equipment and associated fences, housings, enclosures, and supporting structures shall be grounded. Exception: If isolated from ground and located such that any person in contact with ground cannot contact such metal parts when the equipment is energized, the metal parts shall not be required to be grounded. Informational Note: See 250.110, Exception No. 2, for pole-mounted distribution apparatus. [250.190(A)](https://2023.antflix.net#250.190(A))
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https://2023.antflix.net#250.190(A)
|
Chapter 2 Wiring and Protection
|
250.190(B)
|
If a grounding electrode conductor connects non-current-carrying metal parts to ground, the grounding electrode conductor shall be sized in accordance with Table 250.66, based on the size of the largest ungrounded service, feeder, or branch-circuit conductors supplying the equipment. The grounding electrode conductor shall not be smaller than 6 AWG copper or 4 AWG aluminum or copper-clad aluminum. [250.190(B)](https://2023.antflix.net#250.190(B))
|
https://2023.antflix.net#250.190(B)
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Chapter 2 Wiring and Protection
|
250.190(C)
|
Equipment grounding conductors shall comply with 250.190(C)(1) through (C)(3). [250.190(C)](https://2023.antflix.net#250.190(C))
|
https://2023.antflix.net#250.190(C)
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Chapter 2 Wiring and Protection
|
250.190(C)(1)
|
Equipment grounding conductors that are not an integral part of a cable assembly shall not be smaller than 6 AWG copper or 4 AWG aluminum or copper-clad aluminum. [250.190(C)(1)](https://2023.antflix.net#250.190(C)(1))
|
https://2023.antflix.net#250.190(C)(1)
|
Chapter 2 Wiring and Protection
|
250.190(C)(2)
|
The metallic insulation shield encircling the current-carrying conductors shall be permitted to be used as an equipment grounding conductor, if it is rated for clearing time of ground-fault current protective device operation without damaging the metallic shield. The metallic tape insulation shield and drain wire insulation shield shall not be used as an equipment grounding conductor for solidly grounded systems. [250.190(C)(2)](https://2023.antflix.net#250.190(C)(2))
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https://2023.antflix.net#250.190(C)(2)
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Chapter 2 Wiring and Protection
|
250.190(C)(3)
|
Equipment grounding conductors shall be sized in accordance with Table 250.122 based on the current rating of the fuse or the overcurrent setting of the protective relay. Informational Note: The overcurrent rating for a circuit breaker is the combination of the current transformer ratio and the current pickup setting of the protective relay. [250.190(C)(3)](https://2023.antflix.net#250.190(C)(3))
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https://2023.antflix.net#250.190(C)(3)
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Chapter 2 Wiring and Protection
|
250.191
|
For ac substations, the grounding system shall be in accordance with Part III of this article. Informational Note: See IEEE 80, IEEE Guide for Safety in AC Substation Grounding, for further information on outdoor ac substation grounding. [250.191](https://2023.antflix.net#250.191)
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https://2023.antflix.net#250.191
|
Chapter 2 Wiring and Protection
|
250.194
|
Metal fences enclosing, and other metal structures in or surrounding, a substation with exposed electrical conductors and equipment shall be grounded and bonded to limit step, touch, and transfer voltages. [250.194](https://2023.antflix.net#250.194)
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https://2023.antflix.net#250.194
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Chapter 2 Wiring and Protection
|
250.194(A)
|
If metal fences are located within 5 m (16 ft) of the exposed electrical conductors or equipment, the fence shall be bonded to the grounding electrode system with wire-type bonding jumpers as follows: Bonding jumpers shall be installed at each fence corner and at maximum 50 m (160 ft) intervals along the fence.If bare overhead conductors cross the fence, bonding jumpers shall be installed on each side of the crossing.Gates shall be bonded to the gate support post, and each gate support post shall be bonded to the grounding electrode system.Any gate or other opening in the fence shall be bonded across the opening by a buried bonding jumper.The grounding grid or grounding electrode systems shall be extended to cover the swing of all gates.The barbed wire strands above the fence shall be bonded to the grounding electrode system.Alternate designs performed under engineering supervision shall be permitted for grounding or bonding of metal fences.Informational Note No. 1: A nonconducting fence or section may provide isolation for transfer of voltage to other areas.Informational Note No. 2: See IEEE 80, IEEE Guide for Safety In AC Substation Grounding, for design and installation of fence grounding. [250.194(A)](https://2023.antflix.net#250.194(A))
|
https://2023.antflix.net#250.194(A)
|
Chapter 2 Wiring and Protection
|
250.194(B)
|
All exposed conductive metal structures, including guy wires within 2.5 m (8 ft) vertically or 5 m (16 ft) horizontally of exposed conductors or equipment and subject to contact by persons, shall be bonded to the grounding electrode systems in the area. [250.194(B)](https://2023.antflix.net#250.194(B))
|
https://2023.antflix.net#250.194(B)
|
Chapter 3 Wiring Methods and Materials
|
300.1(A)
|
This article covers general requirements for wiring methods and materials for all wiring installations unless modified by other articles in Chapter 3. [300.1(A)](https://2023.antflix.net#300.1(A))
|
https://2023.antflix.net#300.1(A)
|
Chapter 3 Wiring Methods and Materials
|
300.1(B)
|
The requirements of this article are not intended to apply to the conductors that form an integral part of equipment, such as motors, controllers, motor control centers, or factory-assembled control equipment or listed utilization equipment. [300.1(B)](https://2023.antflix.net#300.1(B))
|
https://2023.antflix.net#300.1(B)
|
Chapter 3 Wiring Methods and Materials
|
300.1(C)
|
Metric designators and trade sizes for conduit, tubing, and associated fittings and accessories shall be in accordance with Table 300.1(C). Table 300.1(C) Metric Designators and Trade Sizes Metric Designator Trade Size 12 3/8 16 1/2 21 3/4 27 1 35 l1/4 41 11/2 53 2 63 21/2 78 3 91 31/2 103 4 129 5 155 6 Note: The metric designators and trade sizes are for identification purposes only and are not actual dimensions. [300.1(C)](https://2023.antflix.net#300.1(C))
|
https://2023.antflix.net#300.1(C)
|
Chapter 3 Wiring Methods and Materials
|
300.2(A)
|
Wiring methods specified in Chapter 3 shall be used for 1000 volts ac, 1500 volts dc, nominal, or less where not specifically limited elsewhere in Chapter 3. They shall be permitted for over 1000 volts ac, 1500 volts dc, nominal, where specifically permitted elsewhere in this Code. [300.2(A)](https://2023.antflix.net#300.2(A))
|
https://2023.antflix.net#300.2(A)
|
Chapter 3 Wiring Methods and Materials
|
300.2(B)
|
Temperature limitation of conductors shall be in accordance with 310.14(A)(3). [300.2(B)](https://2023.antflix.net#300.2(B))
|
https://2023.antflix.net#300.2(B)
|
Chapter 3 Wiring Methods and Materials
|
300.3(A)
|
Single conductors specified in Table 310.4(1) shall only be permitted where installed as part of a recognized wiring method specified in Chapter 3. Exception: Individual conductors shall be permitted where installed as separate overhead conductors in accordance with 225.6. [300.3(A)](https://2023.antflix.net#300.3(A))
|
https://2023.antflix.net#300.3(A)
|
Chapter 3 Wiring Methods and Materials
|
300.3(B)
|
All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors and bonding conductors shall be contained within the same raceway, conduit body, auxiliary gutter, cable tray, cablebus assembly, trench, cable, or cord unless otherwise permitted in accordance with 300.3(B)(1) through (B)(4). [300.3(B)](https://2023.antflix.net#300.3(B))
|
https://2023.antflix.net#300.3(B)
|
Chapter 3 Wiring Methods and Materials
|
300.3(B)(1)
|
Conductors shall be permitted to be run in parallel in accordance with 310.10(G). The requirement to run all circuit conductors within the same raceway, auxiliary gutter, cable tray, trench, cable, or cord shall apply separately to each portion of the paralleled installation, and the equipment grounding conductors shall comply with 250.122. Connections, taps, or extensions made from paralleled conductors shall connect to all conductors of the paralleled set, grounded and ungrounded, as applicable. Parallel runs in cable trays shall comply with 392.20(C). Exception: Conductors installed in nonmetallic raceways run underground shall be permitted to be arranged as isolated phase, neutral, and grounded conductor installations. The raceways shall be installed in close proximity, and the isolated phase, neutral, and grounded conductors shall comply with 300.20(B). [300.3(B)(1)](https://2023.antflix.net#300.3(B)(1))
|
https://2023.antflix.net#300.3(B)(1)
|
Chapter 3 Wiring Methods and Materials
|
300.3(B)(2)
|
Equipment grounding conductors shall be permitted to be installed outside a raceway or cable assembly in accordance with 250.130(C) for certain existing installations or in accordance with 250.134, Exception No. 2, for dc circuits. Equipment bonding conductors shall be permitted to be installed on the outside of raceways in accordance with 250.102(E). [300.3(B)(2)](https://2023.antflix.net#300.3(B)(2))
|
https://2023.antflix.net#300.3(B)(2)
|
Chapter 3 Wiring Methods and Materials
|
300.3(B)(3)
|
Conductors in wiring methods with a nonmetallic or other nonmagnetic sheath, where run in different raceways, auxiliary gutters, cable trays, trenches, cables, or cords, shall comply with 300.20(B). Conductors in single-conductor Type MI cable with a nonmagnetic sheath shall comply with 332.31. Conductors of single-conductor Type MC cable with a nonmagnetic sheath shall comply with 330.31, 330.116, and 300.20(B). [300.3(B)(3)](https://2023.antflix.net#300.3(B)(3))
|
https://2023.antflix.net#300.3(B)(3)
|
Chapter 3 Wiring Methods and Materials
|
300.3(B)(4)
|
Where an auxiliary gutter runs between a column-width panelboard and a pull box, and the pull box includes neutral terminations, the neutral conductors of circuits supplied from the panelboard shall be permitted to originate in the pull box. [300.3(B)(4)](https://2023.antflix.net#300.3(B)(4))
|
https://2023.antflix.net#300.3(B)(4)
|
Chapter 3 Wiring Methods and Materials
|
300.3(C)(1)
|
Conductors of ac and dc circuits rated 1000 volts ac, 1500 volts dc, nominal, or less shall be permitted to occupy the same equipment wiring enclosure, cable, or raceway. All conductors shall have an insulation rating equal to at least the maximum circuit voltage applied to any conductor within the enclosure, cable, or raceway. Secondary wiring to electric-discharge lamps of 1000 volts ac, 1500 volts dc, or less, if insulated for the secondary voltage involved, shall be permitted to occupy the same luminaire, sign, or outline lighting enclosure as the branch-circuit conductors. Informational Note No. 1: See 725.136(A) for Class 2 and Class 3 circuit conductors. Informational Note No. 2: See 690.31(B) for photovoltaic source and output circuits. [300.3(C)(1)](https://2023.antflix.net#300.3(C)(1))
|
https://2023.antflix.net#300.3(C)(1)
|
Chapter 3 Wiring Methods and Materials
|
300.3(C)(2)
|
Conductors of circuits rated over 1000 volts ac, 1500 volts dc, nominal, shall not occupy the same equipment wiring enclosure, cable, or raceway with conductors of circuits rated 1000 volts ac, 1500 volts dc, nominal, or less unless permitted in accordance with 305.4. [300.3(C)(2)](https://2023.antflix.net#300.3(C)(2))
|
https://2023.antflix.net#300.3(C)(2)
|
Chapter 3 Wiring Methods and Materials
|
300.4
|
Where subject to physical damage, conductors, raceways, and cables shall be protected. [300.4](https://2023.antflix.net#300.4)
|
https://2023.antflix.net#300.4
|
Chapter 3 Wiring Methods and Materials
|
300.4(A)(1)
|
In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed through bored holes in joists, rafters, or wood members, holes shall be bored so that the edge of the hole is not less than 32 mm (11/4 in.) from the edges of the wood member. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by screws or nails by a steel plate(s) or bushing(s) at least 1.6 mm (1/16 in.) thick, and of appropriate length and width, installed to cover the area of the wiring. Exception No. 1: Steel plates shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid PVC conduit, RTRC, or electrical metallic tubing. Exception No. 2: A listed and marked steel plate less than 1.6 mm (1/16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted. [300.4(A)(1)](https://2023.antflix.net#300.4(A)(1))
|
https://2023.antflix.net#300.4(A)(1)
|
Chapter 3 Wiring Methods and Materials
|
300.4(A)(2)
|
Where there is no objection because of weakening the building structure, in both exposed and concealed locations, cables or raceways shall be permitted to be laid in notches in wood studs, joists, rafters, or other wood members where the cable or raceway at those points is protected from penetration by nails or screws by a steel plate at least 1.6 mm (1/16 in.) thick, and of appropriate length and width, installed to cover the area of the wiring. The steel plate shall be installed before the building finish is applied. Exception No. 1: Steel plates shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing. Exception No. 2: A listed and marked steel plate less than 1.6 mm (1/16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted. [300.4(A)(2)](https://2023.antflix.net#300.4(A)(2))
|
https://2023.antflix.net#300.4(A)(2)
|
Chapter 3 Wiring Methods and Materials
|
300.4(B)(1)
|
In both exposed and concealed locations where nonmetallic-sheathed cables pass through either factory- or field-punched, cut, or drilled slots or holes in metal members, the cable shall be protected by listed bushings or listed grommets covering all metal edges that are securely fastened in the opening prior to installation of the cable. [300.4(B)(1)](https://2023.antflix.net#300.4(B)(1))
|
https://2023.antflix.net#300.4(B)(1)
|
Chapter 3 Wiring Methods and Materials
|
300.4(B)(2)
|
Where nails or screws are likely to penetrate nonmetallic-sheathed cable or electrical nonmetallic tubing, a steel sleeve, steel plate, or steel clip not less than 1.6 mm (1/16 in.) in thickness shall be used to protect the cable or tubing. Exception: A listed and marked steel plate less than 1.6 mm (1/16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted. [300.4(B)(2)](https://2023.antflix.net#300.4(B)(2))
|
https://2023.antflix.net#300.4(B)(2)
|
Chapter 3 Wiring Methods and Materials
|
300.4(C)
|
Cables or raceway-type wiring methods, installed behind panels designed to allow access shall be supported according to their applicable articles. [300.4(C)](https://2023.antflix.net#300.4(C))
|
https://2023.antflix.net#300.4(C)
|
Chapter 3 Wiring Methods and Materials
|
300.4(D)
|
In both exposed and concealed locations, where a cable- or raceway-type wiring method is installed parallel to framing members, such as joists, rafters, or studs, or is installed parallel to furring strips, the cable or raceway shall be installed and supported so that the nearest outside surface of the cable or raceway is not less than 32 mm (11/4 in.) from the nearest edge of the framing member or furring strips where nails or screws are likely to penetrate. Where this distance cannot be maintained, the cable or raceway shall be protected from penetration by nails or screws by a steel plate, sleeve, or equivalent at least 1.6 mm (1/16 in.) thick. Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing. Exception No. 2: For concealed work in finished buildings, or finished panels for prefabricated buildings where such supporting is impracticable, it shall be permissible to fish the cables between access points. Exception No. 3: A listed and marked steel plate less than 1.6 mm (1/16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted. [300.4(D)](https://2023.antflix.net#300.4(D))
|
https://2023.antflix.net#300.4(D)
|
Chapter 3 Wiring Methods and Materials
|
300.4(E)
|
A cable, raceway, or box, installed in exposed or concealed locations under metal-corrugated sheet roof decking, shall be installed and supported so there is not less than 38 mm (l1/2 in.) measured from the lowest surface of the roof decking to the top of the cable, raceway, or box. A cable, raceway, or box shall not be installed in concealed locations in metal-corrugated, sheet decking—type roof. Informational Note: Roof decking material is often repaired or replaced after the initial raceway or cabling and roofing installation and might be penetrated by screws or other mechanical devices designed to provide "hold down" strength of the waterproof membrane or roof insulating material. Exception No. 1: Rigid metal conduit and intermediate metal conduit, with listed steel or malleable iron fittings and boxes, shall not be required to comply with 300.4(E). Exception No. 2: The 38 mm (11/2 in.) spacing is not required where metal-corrugated sheet roof decking is covered with a minimum thickness 50 mm (2 in.) concrete slab, measured from the top of the corrugated roofing. [300.4(E)](https://2023.antflix.net#300.4(E))
|
https://2023.antflix.net#300.4(E)
|
Chapter 3 Wiring Methods and Materials
|
300.4(F)
|
Cable- or raceway-type wiring methods installed in a groove, to be covered by wallboard, siding, paneling, carpeting, or similar finish, shall be protected by 1.6 mm (1/16 in.) thick steel plate, sleeve, or equivalent or by not less than 32-mm (l1/4-in.) free space for the full length of the groove in which the cable or raceway is installed. Exception No. 1: Steel plates, sleeves, or the equivalent shall not be required to protect rigid metal conduit, intermediate metal conduit, rigid PVC conduit, RTRC, or electrical metallic tubing. Exception No. 2: A listed and marked steel plate less than 1.6 mm (1/16 in.) thick that provides equal or better protection against nail or screw penetration shall be permitted. [300.4(F)](https://2023.antflix.net#300.4(F))
|
https://2023.antflix.net#300.4(F)
|
Chapter 3 Wiring Methods and Materials
|
300.4(G)
|
Where raceways contain 4 AWG or larger insulated circuit conductors, and these conductors enter a cabinet, a box, an enclosure, or a raceway, prior to the installation of conductors, the conductors shall be protected in accordance with any of the following: An identified fitting providing a smoothly rounded insulating surfaceA listed metal fitting that has smoothly rounded edgesSeparation from the fitting or raceway using an identified insulating material that is securely fastened in placeThreaded hubs or bosses that are an integral part of a cabinet, box, enclosure, or raceway providing a smoothly rounded or flared entry for conductorsConduit bushings constructed wholly of insulating material shall not be used to secure a fitting or raceway. The insulating fitting or insulating material shall have a temperature rating not less than the insulation temperature rating of the installed conductors. [300.4(G)](https://2023.antflix.net#300.4(G))
|
https://2023.antflix.net#300.4(G)
|
Chapter 3 Wiring Methods and Materials
|
300.4(H)
|
A listed expansion/deflection fitting or other approved means shall be used where a raceway crosses a structural joint intended for expansion, contraction, or deflection, used in buildings, bridges, parking garages, or other structures. [300.4(H)](https://2023.antflix.net#300.4(H))
|
https://2023.antflix.net#300.4(H)
|
Chapter 3 Wiring Methods and Materials
|
300.5(A)
|
Direct-buried cable, conduit, or other raceways shall be installed to meet the minimum cover requirements of Table 300.5(A).Table 300.5(A) Minimum Cover Requirements, 0 to 1000 Volts ac, 1500 Volts dc, Nominal, Burial in Millimeters (Inches) Location of Wiring Method or Circuit Type of Wiring Method or Circuit Column 1 Direct Burial Cables or Conductors Column 2 Rigid Metal Conduit or Intermediate Metal Conduit Column 3 Electrical Metallic Tubing, Nonmetallic Raceways Listed for Direct Burial Without Concrete Encasement, or Other Approved Raceways Column 4 Residential Branch Circuits Rated 120 Volts or Less with GFCI Protection and Maximum Overcurrent Protection of 20 Amperes Column 5 Circuits for Control of Irrigation and Landscape Lighting Limited to Not More Than 30 Volts and Installed with Type UF or in Other Identified Cable or Raceway mm in. mm in. mm in. mm in. mm in. All locations not specified below 600 24 150 6 450 18 300 12 1501,2 61,2 In trench below 50 mm (2 in.) thick concrete or equivalent 450 18 150 6 300 12 150 6 150 6 Under a building 0 0 0 0 0 0 0 0 0 0 (in raceway or Type MC or Type MI cable identified for direct burial) (in raceway or Type MC or Type MI cable identified for direct burial) (in raceway or Type MC or Type MI cable identified for direct burial) Under minimum of 102 mm (4 in.) thick concrete exterior slab with no vehicular traffic and the slab extending not less than 152 mm (6 in.) beyond the underground installation 450 18 100 4 100 4 150 (direct burial) 6 150(direct burial) 6 100(in raceway) 4 100(in raceway) 4 Under streets, highways, roads, alleys, driveways, and parking lots 600 24 600 24 600 24 600 24 600 24 One- and two-family dwelling driveways and outdoor parking areas, and used only for dwelling-related purposes 450 18 450 18 450 18 300 12 450 18 In or under airport runways, including adjacent areas where trespassing is prohibited 450 18 450 18 450 18 450 18 450 18 1A lesser depth shall be permitted where specified in the installation instructions of a listed low-voltage lighting system. 2A depth of 150 mm (6 in.) shall be permitted for pool, spa, and fountain lighting, installed in a nonmetallic raceway, limited to not more than 30 volts where part of a listed low-voltage lighting system. Notes:Cover shall be defined as the shortest distance in mm (in.) measured between a point on the top surface of any direct-buried conductor, cable, conduit, or other raceway and the top surface of finished grade, concrete, or similar cover.Raceways approved for burial only where concrete encased shall require a concrete envelope not less than 50 mm (2 in.) thick.Lesser depths shall be permitted where cables and conductors rise for terminations or splices or where access is otherwise required.Where one of the wiring method types listed in Columns 1 through 3 is used for one of the circuit types in Columns 4 and 5, the shallowest depth of burial shall be permitted.Where solid rock prevents compliance with the cover depths specified in this table, the wiring shall be installed in a metal raceway, or a nonmetallic raceway permitted for direct burial. The raceways shall be covered by a minimum of 50 mm (2 in.) of concrete extending down to rock.Directly buried electrical metallic tubing (EMT) shall comply with 358.10. [300.5(A)](https://2023.antflix.net#300.5(A))
|
https://2023.antflix.net#300.5(A)
|
Chapter 3 Wiring Methods and Materials
|
300.5(B)
|
The interior of enclosures or raceways installed underground shall be considered to be a wet location. Insulated conductors and cables installed in these enclosures or raceways in underground installations shall comply with 310.10(C). [300.5(B)](https://2023.antflix.net#300.5(B))
|
https://2023.antflix.net#300.5(B)
|
Chapter 3 Wiring Methods and Materials
|
300.5(C)
|
Underground cable and conductors installed under a building shall be in a raceway. Exception No. 1: Type MI cable shall be permitted under a building without installation in a raceway where embedded in concrete, fill, or other masonry in accordance with 332.10(6) or in underground runs where suitably protected against physical damage and corrosive conditions in accordance with 332.10(10). Exception No. 2: Type MC cable listed for direct burial or concrete encasement shall be permitted under a building without installation in a raceway in accordance with 330.10(A)(5) and in wet locations in accordance with 330.10(A)(11). [300.5(C)](https://2023.antflix.net#300.5(C))
|
https://2023.antflix.net#300.5(C)
|
Chapter 3 Wiring Methods and Materials
|
300.5(D)
|
Conductors and cables shall be protected from damage in accordance with 300.5(D)(1) through (D)(4). [300.5(D)](https://2023.antflix.net#300.5(D))
|
https://2023.antflix.net#300.5(D)
|
Chapter 3 Wiring Methods and Materials
|
300.5(D)(1)
|
Direct-buried conductors and cables emerging from grade and specified in Columns 1 and 4 of Table 300.5(A) shall be protected by enclosures or raceways extending from the minimum cover distance below grade required by 300.5(A) to a point at least 2.5 m (8 ft) above finished grade. In no case shall the protection be required to exceed 450 mm (18 in.) below finished grade. [300.5(D)(1)](https://2023.antflix.net#300.5(D)(1))
|
https://2023.antflix.net#300.5(D)(1)
|
Chapter 3 Wiring Methods and Materials
|
300.5(D)(2)
|
Conductors entering a building shall be protected to the point of entrance. [300.5(D)(2)](https://2023.antflix.net#300.5(D)(2))
|
https://2023.antflix.net#300.5(D)(2)
|
Chapter 3 Wiring Methods and Materials
|
300.5(D)(3)
|
Underground service conductors that are not encased in concrete and that are buried 450 mm (18 in.) or more below grade shall have their location identified by a warning ribbon that is placed in the trench at least 300 mm (12 in.) above the underground installation. [300.5(D)(3)](https://2023.antflix.net#300.5(D)(3))
|
https://2023.antflix.net#300.5(D)(3)
|
Chapter 3 Wiring Methods and Materials
|
300.5(D)(4)
|
Where the enclosure or raceway is subject to physical damage, the conductors shall be installed in electrical metallic tubing, rigid metal conduit, intermediate metal conduit, RTRC-XW, Schedule 80 PVC conduit, or equivalent. [300.5(D)(4)](https://2023.antflix.net#300.5(D)(4))
|
https://2023.antflix.net#300.5(D)(4)
|
Chapter 3 Wiring Methods and Materials
|
300.5(E)
|
Direct-buried conductors or cables shall be permitted to be spliced or tapped without the use of splice boxes. The splices or taps shall be made in accordance with 110.14(B). [300.5(E)](https://2023.antflix.net#300.5(E))
|
https://2023.antflix.net#300.5(E)
|
Chapter 3 Wiring Methods and Materials
|
300.5(F)
|
Backfill that contains large rocks, paving materials, cinders, large or sharply angular substances, or corrosive material shall not be placed in an excavation where materials might damage raceways, cables, conductors, or other substructures or prevent adequate compaction of fill or contribute to corrosion of raceways, cables, or other substructures. Where necessary to prevent physical damage to the raceway, cable, or conductor, protection shall be provided in the form of granular or selected material, suitable running boards, suitable sleeves, or other approved means. [300.5(F)](https://2023.antflix.net#300.5(F))
|
https://2023.antflix.net#300.5(F)
|
Chapter 3 Wiring Methods and Materials
|
300.5(G)
|
Conduits or raceways through which moisture might contact live parts shall be sealed or plugged at either or both ends. Spare or unused raceways shall also be sealed. Sealants shall be identified for use with the cable insulation, conductor insulation, bare conductor, shield, or other components. Informational Note: Presence of hazardous gases or vapors might also necessitate the sealing of underground conduits or raceways entering buildings. [300.5(G)](https://2023.antflix.net#300.5(G))
|
https://2023.antflix.net#300.5(G)
|
Chapter 3 Wiring Methods and Materials
|
300.5(H)
|
A bushing, or terminal fitting, with an integral bushed opening shall be used at the end of a conduit or other raceway that terminates underground where the conductors or cables emerge as a direct burial wiring method. A seal incorporating the physical protection characteristics of a bushing shall be permitted to be used in lieu of a bushing. [300.5(H)](https://2023.antflix.net#300.5(H))
|
https://2023.antflix.net#300.5(H)
|
Chapter 3 Wiring Methods and Materials
|
300.5(I)
|
All conductors of the same circuit and, where used, the grounded conductor and all equipment grounding conductors shall be installed in the same raceway or cable or shall be installed in close proximity in the same trench. Exception No. 1: Conductors shall be permitted to be installed in parallel in raceways, multiconductor cables, or direct-buried single conductor cables. Each raceway or multiconductor cable shall contain all conductors of the same circuit, including equipment grounding conductors. Each direct-buried single conductor cable shall be located in close proximity in the trench to the other single conductor cables in the same parallel set of conductors in the circuit, including equipment grounding conductors. Exception No. 2: Isolated phase, polarity, grounded conductor, and equipment grounding and bonding conductor installations shall be permitted in nonmetallic raceways or cables with a nonmetallic covering or nonmagnetic sheath in close proximity where conductors are paralleled as permitted in 310.10(G), and where the conditions of 300.20(B) are met. [300.5(I)](https://2023.antflix.net#300.5(I))
|
https://2023.antflix.net#300.5(I)
|
Chapter 3 Wiring Methods and Materials
|
300.5(J)
|
Where direct-buried conductors, raceways, or cables are subject to movement by settlement or frost, direct-buried conductors, raceways, or cables shall be arranged so as to prevent damage to the enclosed conductors or to equipment connected to the raceways. Informational Note: This section recognizes "S" loops in underground direct burial cables and conductors to raceway transitions, expansion fittings in raceway risers to fixed equipment, and, generally, the provision of flexible connections to equipment subject to settlement or frost heaves. [300.5(J)](https://2023.antflix.net#300.5(J))
|
https://2023.antflix.net#300.5(J)
|
Chapter 3 Wiring Methods and Materials
|
300.5(K)
|
Cables or raceways installed using directional boring equipment shall be approved for the purpose. [300.5(K)](https://2023.antflix.net#300.5(K))
|
https://2023.antflix.net#300.5(K)
|
Chapter 3 Wiring Methods and Materials
|
300.6
|
Raceways, cable trays, cablebus, auxiliary gutters, cable armor, boxes, cable sheathing, cabinets, enclosures (other than surrounding fences and walls), elbows, couplings, fittings, supports, and support hardware shall be of materials suitable for the environment in which they are to be installed. [300.6](https://2023.antflix.net#300.6)
|
https://2023.antflix.net#300.6
|
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