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Chapter 3 Wiring Methods and Materials
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310.10(E)
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Conductors used for direct-burial applications shall be of a type identified for such use. [310.10(E)](https://2023.antflix.net#310.10(E))
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https://2023.antflix.net#310.10(E)
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Chapter 3 Wiring Methods and Materials
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310.10(F)
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Conductors exposed to oils, greases, vapors, gases, fumes, liquids, or other substances having a deleterious effect on the conductor or insulation shall be of a type suitable for the application. [310.10(F)](https://2023.antflix.net#310.10(F))
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https://2023.antflix.net#310.10(F)
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Chapter 3 Wiring Methods and Materials
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310.10(G)(1)
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Aluminum, copper-clad aluminum, or copper circuit conductors for each ungrounded conductor, grounded conductor, or neutral conductor shall be permitted to be connected in parallel (electrically joined at both ends) only in sizes 1/0 AWG and larger and shall be installed in accordance with 310.10(G)(2) through (G)(4). Exception No. 1: Conductors in sizes smaller than 1/0 AWG shall be permitted to be run in parallel to supply control power to indicating instruments, contactors, relays, solenoids, and similar control devices, or for frequencies of 360 Hz and higher, provided all of the following apply: (1) They are contained within the same raceway or cable. (2) The ampacity of each individual conductor is sufficient to carry the entire load current shared by the parallel conductors. (3) The overcurrent protection is such that the ampacity of each individual conductor will not be exceeded if one or more of the parallel conductors become inadvertently disconnected. Exception No. 2: Under engineering supervision, 2 AWG and 1 AWG grounded neutral conductors shall be permitted to be installed in parallel for existing installations. Informational Note: Exception No. 2 can be used to alleviate overheating of neutral conductors in existing installations due to high content of triplen harmonic currents. [310.10(G)(1)](https://2023.antflix.net#310.10(G)(1))
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https://2023.antflix.net#310.10(G)(1)
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Chapter 3 Wiring Methods and Materials
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310.10(G)(2)
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The paralleled conductors that comprise each ungrounded conductor, grounded conductor, neutral conductor, equipment grounding conductor, equipment bonding jumper, or supply-side bonding jumper shall comply with all of the following: Be the same lengthConsist of the same conductor materialBe the same size in circular mil areaHave the same insulation typeBe terminated in the same manner [310.10(G)(2)](https://2023.antflix.net#310.10(G)(2))
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https://2023.antflix.net#310.10(G)(2)
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Chapter 3 Wiring Methods and Materials
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310.10(G)(3)
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Where run in separate cables or raceways, the cables or raceways with conductors shall have the same number of conductors and shall have the same electrical characteristics. Conductors composing one paralleled set shall not be required to have the same physical characteristics as those of another paralleled set. [310.10(G)(3)](https://2023.antflix.net#310.10(G)(3))
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https://2023.antflix.net#310.10(G)(3)
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Chapter 3 Wiring Methods and Materials
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310.10(G)(4)
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Conductors installed in parallel shall comply with 310.15(B) and (C). [310.10(G)(4)](https://2023.antflix.net#310.10(G)(4))
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https://2023.antflix.net#310.10(G)(4)
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Chapter 3 Wiring Methods and Materials
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310.10(G)(5)
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Where parallel equipment grounding conductors are used, they shall be sized in accordance with 250.122. Sectioned equipment grounding conductors smaller than 1/0 AWG shall be permitted in multiconductor cables, if the combined circular mil area of the sectioned equipment grounding conductors in each cable complies with 250.122. [310.10(G)(5)](https://2023.antflix.net#310.10(G)(5))
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https://2023.antflix.net#310.10(G)(5)
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Chapter 3 Wiring Methods and Materials
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310.10(G)(6)
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Where parallel equipment bonding jumpers or supply-side bonding jumpers are installed in raceways, they shall be sized and installed in accordance with 250.102. [310.10(G)(6)](https://2023.antflix.net#310.10(G)(6))
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https://2023.antflix.net#310.10(G)(6)
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Chapter 3 Wiring Methods and Materials
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310.12
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For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, service and feeder conductors supplied by a single-phase, 120/240-volt system shall be permitted to be sized in accordance with 310.12(A) through (D). For one-family dwellings and the individual dwelling units of two-family and multifamily dwellings, single-phase feeder conductors consisting of two ungrounded conductors and the neutral conductor from a 208Y/120 volt system shall be permitted to be sized in accordance with 310.12(A) through (C). [310.12](https://2023.antflix.net#310.12)
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https://2023.antflix.net#310.12
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Chapter 3 Wiring Methods and Materials
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310.12(A)
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For a service rated 100 amperes through 400 amperes, the service conductors supplying the entire load associated with a one-family dwelling, or the service conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the service rating. If no adjustment or correction factors are required, Table 310.12(A) shall be permitted to be applied.Table 310.12(A) Single-Phase Dwelling Services and Feeders Service or Feeder Rating (Amperes) Conductor (AWG or kcmil) Copper Aluminum or Copper-Clad Aluminum 100 4 2 110 3 1 125 2 1/0 150 1 2/0 175 1/0 3/0 200 2/0 4/0 225 3/0 250 250 4/0 300 300 250 350 350 350 500 400 400 600 Note: If no adjustment or correction factors are required, this table shall be permitted to be applied. [310.12(A)](https://2023.antflix.net#310.12(A))
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https://2023.antflix.net#310.12(A)
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Chapter 3 Wiring Methods and Materials
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310.12(B)
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For a feeder rated 100 amperes through 400 amperes, the feeder conductors supplying the entire load associated with a one-family dwelling, or the feeder conductors supplying the entire load associated with an individual dwelling unit in a two-family or multifamily dwelling, shall be permitted to have an ampacity not less than 83 percent of the feeder rating. If no adjustment or correction factors are required, Table 310.12(A) shall be permitted to be applied. [310.12(B)](https://2023.antflix.net#310.12(B))
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https://2023.antflix.net#310.12(B)
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Chapter 3 Wiring Methods and Materials
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310.12(C)
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In no case shall a feeder for an individual dwelling unit be required to have an ampacity greater than that specified in 310.12(A) or (B). [310.12(C)](https://2023.antflix.net#310.12(C))
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https://2023.antflix.net#310.12(C)
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Chapter 3 Wiring Methods and Materials
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310.12(D)
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Grounded conductors shall be permitted to be sized smaller than the ungrounded conductors, if the requirements of 220.61 and 230.42 for service conductors or the requirements of 215.2 and 220.61 for feeder conductors are met. Where correction or adjustment factors are required by 310.15(B) or (C), they shall be permitted to be applied to the ampacity associated with the temperature rating of the conductor. Informational Note No. 1: See 240.6(A) for standard ampere ratings for fuses and inverse time circuit breakers. Informational Note No. 2: See Informative Annex D, Example D7. [310.12(D)](https://2023.antflix.net#310.12(D))
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https://2023.antflix.net#310.12(D)
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Chapter 3 Wiring Methods and Materials
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310.14(A)(1)
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Ampacities for conductors shall be permitted to be determined by tables as provided in 310.15 or under engineering supervision as provided in 310.14(B). Informational Note No. 1: See 210.19, Informational Note, for voltage drop on branch circuits that this section does not take into consideration. See 215.2(A)(2), Informational Note No. 2, for voltage drop on feeders that this section does not take into consideration. Informational Note No. 2: See NFPA 79-2021, Electrical Standard for Industrial Machinery, Table 12.5.1, for the allowable ampacities of Type MTW wire. [310.14(A)(1)](https://2023.antflix.net#310.14(A)(1))
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https://2023.antflix.net#310.14(A)(1)
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Chapter 3 Wiring Methods and Materials
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310.14(A)(2)
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Where more than one ampacity applies for a given circuit length, the lowest value shall be used. Exception: Where different ampacities apply to portions of a circuit, the higher ampacity shall be permitted to be used if the total portion(s) of the circuit with lower ampacity does not exceed the lesser of 3.0 m (10 ft) or 10 percent of the total circuit. Informational Note: See 110.14(C) for conductor temperature limitations due to termination provisions. [310.14(A)(2)](https://2023.antflix.net#310.14(A)(2))
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https://2023.antflix.net#310.14(A)(2)
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Chapter 3 Wiring Methods and Materials
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310.14(A)(3)
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No conductor shall be used in such a manner that its operating temperature exceeds that designated for the type of insulated conductor involved. In no case shall conductors be associated together in such a way, with respect to type of circuit, the wiring method employed, or the number of conductors, that the limiting temperature of any conductor is exceeded. Informational Note No. 1: See Table 310.4(1) and Table 315.10(A) for the temperature rating of a conductor that is the maximum temperature, at any location along its length, that the conductor can withstand over a prolonged time period without serious degradation. The ampacity tables of Article 310 and the ampacity tables of Informative Annex B, the ambient temperature correction factors in 310.15(B), and the notes to the tables provide guidance for coordinating conductor sizes, types, ampacities, ambient temperatures, and number of associated conductors. The principal determinants of operating temperature are as follows:Ambient temperature - ambient temperature may vary along the conductor length as well as from time to time.Heat generated internally in the conductor as the result of load current flow, including fundamental and harmonic currents.The rate at which generated heat dissipates into the ambient medium. Thermal insulation that covers or surrounds conductors affects the rate of heat dissipation.Adjacent load-carrying conductors - adjacent conductors have the dual effect of raising the ambient temperature and impeding heat dissipation.Informational Note No. 2: Refer to 110.14(C) for the temperature limitation of terminations. [310.14(A)(3)](https://2023.antflix.net#310.14(A)(3))
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https://2023.antflix.net#310.14(A)(3)
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Chapter 3 Wiring Methods and Materials
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310.14(B)
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Under engineering supervision, conductor ampacities shall be permitted to be calculated by means of Equation 310.14(B). [310.14(B)] where: Tc = conductor temperature in degrees Celsius (°C) Ta = ambient temperature in degrees Celsius (°C) Rdc = dc resistance of 305 mm (1 ft) of conductor in microohms at temperature, Tc Yc = component ac resistance resulting from skin effect and proximity effect Rca = effective thermal resistance between conductor and surrounding ambient [310.14(B)](https://2023.antflix.net#310.14(B))
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https://2023.antflix.net#310.14(B)
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Chapter 3 Wiring Methods and Materials
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310.15(A)
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Ampacities for conductors rated 0 volts to 2000 volts shall be as specified in the Ampacity Table 310.16 through Table 310.21, as modified by 310.15(A) through (F) and 310.12. Under engineering supervision, ampacities of sizes not shown in ampacity tables for conductors meeting the general wiring requirements shall be permitted to be determined by interpolation of the adjacent conductors based on the conductor's circular-mil area. The temperature correction and adjustment factors shall be permitted to be applied to the ampacity for the temperature rating of the conductor, if the corrected and adjusted ampacity does not exceed the ampacity for the temperature rating of the termination in accordance with 110.14(C). Informational Note No. 1: Table 310.16 through Table 310.19 are application tables for use in determining conductor sizes on loads calculated in accordance with Part II, Part III, Part IV, or Part V of Article 220. Ampacities result from consideration of one or more of the following:Temperature compatibility with connected equipment, especially the connection pointsCoordination with circuit and system overcurrent protectionCompliance with the requirements of product listings or certifications.Preservation of the safety benefits of established industry practices and standardized proceduresInformational Note No. 2: See Chapter 9, Table 8, Conductor Properties, for conductor area. Interpolation is based on the conductor circular-mil area and not the conductor overall area.Informational Note No. 3: See 400.5 for the ampacities of flexible cords and cables. See 402.5 for the ampacities of fixture wires.Informational Note No. 4: See Table 310.4(1) and Table 310.4(2) for explanation of type letters used in tables and for recognized sizes of conductors for the various conductor insulations. See 310.1 through 310.14 and the various articles of this Code for installation requirements. See Table 400.4, Table 400.5(A)(1), and Table 400.5(A)(2) for flexible cords. [310.15(A)](https://2023.antflix.net#310.15(A))
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https://2023.antflix.net#310.15(A)
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Chapter 3 Wiring Methods and Materials
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310.15(B)(1)
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Ampacities for ambient temperatures other than those shown in the ampacity tables shall be corrected in accordance with Table 310.15(B)(1)(1) or Table 310.15(B)(1)(2), or shall be permitted to be calculated using Equation 310.15(B)(1). [310.15(B)(1)] where: I' = ampacity corrected for ambient temperature I = ampacity shown in the tables Tc = temperature rating of conductor (°C) Ta' = new ambient temperature (°C) Ta = ambient temperature used in the table (°C)
Table 310.15(B)(1)(1) Ambient Temperature Correction Factors Based on 30°C (86°F) For ambient temperatures other than 30°C (86°F), multiply the ampacities specified in the ampacity tables by the appropriate correction factor shown below. Ambient Temperature (°C) Temperature Rating of Conductor Ambient Temperature (°F) 60°C 75°C 90°C 10 or less 1.29 1.20 1.15 50 or less 11—15 1.22 1.15 1.12 51—59 16—20 1.15 1.11 1.08 60—68 21—25 1.08 1.05 1.04 69—77 26—30 1.00 1.00 1.00 78—86 31—35 0.91 0.94 0.96 87—95 36—40 0.82 0.88 0.91 96—104 41—45 0.71 0.82 0.87 105—113 46—50 0.58 0.75 0.82 114—122 51—55 0.41 0.67 0.76 123—131 56—60 - 0.58 0.71 132—140 61—65 - 0.47 0.65 141—149 66—70 - 0.33 0.58 150—158 71—75 - - 0.50 159—167 76—80 - - 0.41 168—176 81—85 - - 0.29 177—185 Note: Table 310.15(B)(1)(1) shall be used with Table 310.16 and Table 310.17 as required. Table 310.15(B)(1)(2) Ambient Temperature Correction Factors Based on 40°C (104°F) For ambient temperatures other than 40°C (104°F), multiply the ampacities specified in the ampacity tables by the appropriate correction factor shown below. Ambient Temperature (°C) Temperature Rating of Conductor Ambient Temperature (°F) 60°C 75°C 90°C 150°C 200°C 250°C 10 or less 1.58 1.36 1.26 1.13 1.09 1.07 50 or less 11—15 1.50 1.31 1.22 1.11 1.08 1.06 51—59 16—20 1.41 1.25 1.18 1.09 1.06 1.05 60—68 21—25 1.32 1.2 1.14 1.07 1.05 1.04 69—77 26—30 1.22 1.13 1.10 1.04 1.03 1.02 78—86 31—35 1.12 1.07 1.05 1.02 1.02 1.01 87—95 36—40 1.00 1.00 1.00 1.00 1.00 1.00 96—104 41—45 0.87 0.93 0.95 0.98 0.98 0.99 105—113 46—50 0.71 0.85 0.89 0.95 0.97 0.98 114—122 51—55 0.50 0.76 0.84 0.93 0.95 0.96 123—131 56—60 - 0.65 0.77 0.90 0.94 0.95 132—140 61—65 - 0.53 0.71 0.88 0.92 0.94 141—149 66—70 - 0.38 0.63 0.85 0.90 0.93 150—158 71—75 - - 0.55 0.83 0.88 0.91 159—167 76—80 - - 0.45 0.80 0.87 0.90 168—176 81—90 - - - 0.74 0.83 0.87 177—194 91—100 - - - 0.67 0.79 0.85 195—212 101—110 - - - 0.60 0.75 0.82 213—230 111—120 - - - 0.52 0.71 0.79 231—248 121—130 - - - 0.43 0.66 0.76 249—266 131—140 - - - 0.30 0.61 0.72 267—284 141—160 - - - - 0.50 0.65 285—320 161—180 - - - - 0.35 0.58 321—356 181—200 - - - - - 0.49 357—392 201—225 - - — - - 0.35 393—437 Note: Table 310.15(B)(1)(2) shall be used with Table 310.18, Table 310.19, Table 310.20, and Table. [310.15(B)(1)](https://2023.antflix.net#310.15(B)(1))
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https://2023.antflix.net#310.15(B)(1)
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Chapter 3 Wiring Methods and Materials
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310.15(B)(2)
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For raceways or cables exposed to direct sunlight on or above rooftops where the distance above the roof to the bottom of the raceway or cable is less than 19 mm (3/4 in.), a temperature adder of 33°C (60°F) shall be added to the outdoor temperature to determine the applicable ambient temperature for application of the correction factors in Table 310.15(B)(1)(1) or Table 310.15(B)(1)(2). Exception: Type XHHW-2 insulated conductors shall not be subject to this ampacity adjustment. Informational Note: The ASHRAE Handbook - Fundamentals is one source for the ambient temperatures in various locations. [310.15(B)(2)](https://2023.antflix.net#310.15(B)(2))
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https://2023.antflix.net#310.15(B)(2)
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Chapter 3 Wiring Methods and Materials
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310.15(C)(1)
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The ampacity of each conductor shall be reduced as shown in Table 310.15(C)(1) where the number of current-carrying conductors in a raceway or cable exceeds three, or where single conductors or multiconductor cables not installed in raceways are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.). Each current-carrying conductor of a paralleled set of conductors shall be counted as a current-carrying conductor.
Where conductors of different systems, as provided in 300.3, are installed in a common raceway or cable, the adjustment factors shown in Table 310.15(C)(1) shall apply only to the number of power and lighting conductors.
Informational Note No. 1: See Informative Annex B for adjustment factors for more than three current-carrying conductors in a raceway or cable with load diversity.
Informational Note No. 2: See 366.23 for adjustment factors for conductors and ampacity for bare copper and aluminum bars in auxiliary gutters and 376.22(B) for adjustment factors for conductors in metal wireways.
Where conductors are installed in cable trays, 392.80 shall apply.
Adjustment factors shall not apply to conductors in raceways having a length not exceeding 600 mm (24 in.).
Adjustment factors shall not apply to underground conductors entering or leaving an outdoor trench if those conductors have physical protection in the form of rigid metal conduit, intermediate metal conduit, rigid polyvinyl chloride conduit (PVC), or reinforced thermosetting resin conduit (RTRC) having a length not exceeding 3.05 m (10 ft), and if the number of conductors does not exceed four.
Adjustment factors shall not apply to Type AC cable or to Type MC cable under the following conditions:
The cables do not have an overall outer jacket.
Each cable has not more than three current-carrying conductors.
The conductors are 12 AWG copper.
Not more than 20 current-carrying conductors are installed without maintaining spacing, are stacked, or are supported on "bridle rings."
Exception to (4): If cables meeting the requirements in 310.15(C)(1)(d)(1) through (C)(1)(d)(3) with more than 20 current-carrying conductors are installed longer than 600 mm (24 in.) without maintaining spacing, are stacked, or are supported on bridle rings, a 60 percent adjustment factor shall be applied.
e 310.21 as required.
Table 310.15(C)(1) Adjustment Factors for More Than Three Current-Carrying Conductors
Number of Conductors*
Percent of Values inTable 310.16 Through Table 310.19as Adjusted for Ambient Temperature if Necessary
4—6
80
7—9
70
10—20
50
21—30
45
31—40
40
41 and above
35
*Number of conductors is the total number of conductors in the raceway or cable, including spare conductors. The count shall be adjusted in accordance with 310.15(E) and (F). The count shall not include conductors that are connected to electrical components that cannot be simultaneously energized. [310.15(C)(1)](https://2023.antflix.net#310.15(C)(1))
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https://2023.antflix.net#310.15(C)(1)
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Chapter 3 Wiring Methods and Materials
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310.15(C)(2)
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Spacing between raceways shall be maintained. [310.15(C)(2)](https://2023.antflix.net#310.15(C)(2))
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https://2023.antflix.net#310.15(C)(2)
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Chapter 3 Wiring Methods and Materials
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310.15(D)
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Where bare or covered conductors are installed with insulated conductors, the temperature rating of the bare or covered conductor shall be equal to the lowest temperature rating of the insulated conductors for the purpose of determining ampacity. [310.15(D)](https://2023.antflix.net#310.15(D))
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https://2023.antflix.net#310.15(D)
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Chapter 3 Wiring Methods and Materials
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310.15(E)
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Neutral conductors shall be considered current carrying in accordance with any of the following: A neutral conductor that carries only the unbalanced current from other conductors of the same circuit shall not be required to be counted when applying the provisions of 310.15(C)(1).In a 3-wire circuit consisting of two phase conductors and the neutral conductor of a 4-wire, 3-phase, wye-connected system, the neutral conductor carries approximately the same current as the line-to-neutral load currents of the other conductors and shall be counted when applying 310.15(C)(1).On a 4-wire, 3-phase wye circuit where the major portion of the load consists of nonlinear loads, harmonic currents are present in the neutral conductor; the neutral conductor shall therefore be considered a current-carrying conductor. [310.15(E)](https://2023.antflix.net#310.15(E))
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https://2023.antflix.net#310.15(E)
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Chapter 3 Wiring Methods and Materials
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310.15(F)
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A grounding or bonding conductor shall not be counted when applying the provisions of 310.15(C)(1). [310.15(F)](https://2023.antflix.net#310.15(F))
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https://2023.antflix.net#310.15(F)
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Chapter 3 Wiring Methods and Materials
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310.16
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The ampacities shall be as specified in Table 310.16 where all of the following conditions apply: (1) Conductors are rated 0 volts through 2000 volts. (2) Conductors are rated 60°C (140°F), 75°C (167°F), or 90°C (194°F). (3) Wiring is installed in a 30°C (86°F) ambient temperature. (4) There are not more than three current-carrying conductors. Table 310.16 Ampacities of Insulated Conductors with Not More Than Three Current-Carrying Conductors in Raceway, Cable, or Earth (Directly Buried) Size AWG or kcmil Temperature Rating of Conductor [See Table 310.4(1)] Size AWG or kcmil 60°C (140°F) 75°C (167°F) 90°C (194°F) 60°C (140°F) 75°C (167°F) 90°C (194°F) Types TW, UF Types RHW, THHW, THW, THWN, XHHW, XHWN, USE, ZW Types TBS, SA, SIS, FEP, FEPB, MI, PFA, RHH, RHW-2, THHN, THHW, THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, XHWN, XHWN-2, XHHN, Z, ZW-2 Types TW, UF Types RHW, THHW, THW, THWN, XHHW, XHWN, USE Types TBS, SA, SIS, THHN, THHW, THW-2, THWN-2, RHH, RHW-2, USE-2, XHH, XHHW, XHHW-2, XHWN, XHWN-2, XHHN COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 18* - - 14 - - - - 16* - - 18 - - - - 14* 15 20 25 - - - - 12* 20 25 30 15 20 25 12* 10* 30 35 40 25 30 35 10* 8 40 50 55 35 40 45 8 6 55 65 75 40 50 55 6 4 70 85 95 55 65 75 4 3 85 100 115 65 75 85 3 2 95 115 130 75 90 100 2 1 110 130 145 85 100 115 1 1/0 125 150 170 100 120 135 1/0 2/0 145 175 195 115 135 150 2/0 3/0 165 200 225 130 155 175 3/0 4/0 195 230 260 150 180 205 4/0 250 215 255 290 170 205 230 250 300 240 285 320 195 230 260 300 350 260 310 350 210 250 280 350 400 280 335 380 225 270 305 400 500 320 380 430 260 310 350 500 600 350 420 475 285 340 385 600 700 385 460 520 315 375 425 700 750 400 475 535 320 385 435 750 800 410 490 555 330 395 445 800 900 435 520 585 355 425 480 900 1000 455 545 615 375 445 500 1000 1250 495 590 665 405 485 545 1250 1500 525 625 705 435 520 585 1500 1750 545 650 735 455 545 615 1750 2000 555 665 750 470 560 630 2000 Notes: 1. Section 310.15(B) shall be referenced for ampacity correction factors where the ambient temperature is other than 30°C (86°F). 2. Section 310.15(C)(1) shall be referenced for more than three current-carrying conductors. 3. Section 310.16 shall be referenced for conditions of use. *Section 240.4(D) shall be referenced for conductor overcurrent protection limitations, except as modified elsewhere in the Code. [310.16](https://2023.antflix.net#310.16)
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https://2023.antflix.net#310.16
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Chapter 3 Wiring Methods and Materials
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310.17
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The ampacities shall be as specified in Table 310.17 where all of the following conditions apply: (1) Conductors are rated 0 volts through 2000 volts. (2) Conductors are rated 60°C (140°F), 75°C (167°F), or 90°C (194°F). (3) Wiring is installed in a 30°C (86°F) ambient temperature. Table 310.17 Ampacities of Single-Insulated Conductors in Free Air Size AWG or kcmil Temperature Rating of Conductor [See Table 310.4(1)] Size AWG or kcmil 60°C (140°F) 75°C (167°F) 90°C (194°F) 60°C (140°F) 75°C (167°F) 90°C (194°F) Types TW, UF Types RHW, THHW, THW. THWN, XHHW, XHWN, ZW Types TBS, SA, SIS, FEP, FEPB, MI, PFA, RHH, RHW-2. THHN, THHW. THW-2, THWN-2, USE-2, XHH, XHHW, XHHW-2, XHWN, XHWN-2, XHHN, Z, ZW-2 Types TW, UF Types RHW, THHW, THW, THWN, XHHW, XHWN Types TBS, SA, SIS, THHN, THHW, THW-2, THWN-2, RHH, RHW-2, USE-2, XHH, XHHW, XHHW-2, XHWN, XHWN-2, XHHN COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 18 - - 18 - - - - 16 - - 24 - - - - 14* 25 30 35 - - - - 12* 30 35 40 25 30 35 12* 10* 40 50 55 35 40 45 10* 8 60 70 80 45 55 60 8 6 80 95 105 60 75 85 6 4 105 125 140 80 100 115 4 3 120 145 165 95 115 130 3 2 140 170 190 110 135 150 2 1 165 195 220 130 155 175 1 1/0 195 230 260 150 180 205 1/0 2/0 225 265 300 175 210 235 2/0 3/0 260 310 350 200 240 270 3/0 4/0 300 360 405 235 280 315 4/0 250 340 405 455 265 315 355 250 300 375 445 500 290 350 395 300 350 420 505 570 330 395 445 350 400 455 545 615 355 425 480 400 500 515 620 700 405 485 545 500 600 575 690 780 455 545 615 600 700 630 755 850 500 595 670 700 750 655 785 885 515 620 700 750 800 680 815 920 535 645 725 800 900 730 870 980 580 700 790 900 1000 780 935 1055 625 750 845 1000 1250 890 1065 1200 710 855 965 1250 1500 980 1175 1325 795 950 1070 1500 1750 1070 1280 1445 875 1050 1185 1750 2000 1155 1385 1560 960 1150 1295 2000 Notes: 1. Section 310.15(B) shall be referenced for ampacity correction factors where the ambient temperature is other than 30°C (86°F). 2. Section 310.17 shall be referenced for conditions of use. *Section 240.4(D) shall be referenced for conductor overcurrent protection limitations, except as modified elsewhere in the Code. [310.17](https://2023.antflix.net#310.17)
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https://2023.antflix.net#310.17
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Chapter 3 Wiring Methods and Materials
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310.18
|
The ampacities shall be as specified in Table 310.18 where all of the following conditions apply: (1) Conductors are rated 0 volts through 2000 volts. (2) Conductors are rated 150°C (302°F), 200°C (392°F), or 250°C (482°F). (3) Wiring is installed in a 40°C (104°F) ambient temperature. (4) There are not more than three current-carrying conductors. Table 310.18 Ampacities of Insulated Conductors with Not More Than Three Current-Carrying Conductors in Raceway or Cable Size AWG or kcmil Temperature Rating of Conductor [See Table 310.4(1)] Size AWG or kcmil 150°C (302°F) 200°C (392°F) 250°C (482°F) 150°C (302°F) Type Z Types FEP, FEPB, PFA, SA Types PFAH, TFE Type Z COPPER NICKEL OR NICKEL-COATED COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 14 34 36 39 - 14 12 43 45 54 30 12 10 55 60 73 44 10 8 76 83 93 57 8 6 96 110 117 75 6 4 120 125 148 94 4 3 143 152 166 109 3 2 160 171 191 124 2 1 186 197 215 145 1 1/0 215 229 244 169 1/0 2/0 251 260 273 198 2/0 3/0 288 297 308 227 3/0 4/0 332 346 361 260 4/0 Notes: 1. Section 310.15(B) shall be referenced for ampacity correction factors where the ambient temperature is other than 40°C (104°F). 2. Section 310.15(C)(1) shall be referenced for more than three current-carrying conductors. 3. Section 310.18 shall be referenced for conditions of use. [310.18](https://2023.antflix.net#310.18)
|
https://2023.antflix.net#310.18
|
Chapter 3 Wiring Methods and Materials
|
310.19
|
The ampacities shall be as specified in Fable 310.19 where all of the following conditions apply: (1) Conductors are rated 0 volts through 2000 volts. (2) Conductors are rated up to 250°C (482°F). (3) Wiring is installed in a 40°C (104°F) ambient temperature. Table 310.19 Ampacities of Single-Insulated Conductors in Free Air Size AWG or kcmil Temperature Rating of Conductor [See Table 310.4(1)] Size AWG or kcmil 150°C (302°F) 200°C (392°F) 250°C (482°F) 150°C (302°F) Type Z Types FEP, FEPB, PFA, SA Types PFAH, TFE Type Z COPPER NICKEL OR NICKEL-COATED COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 14 46 54 59 - 14 12 60 68 78 47 12 10 80 90 107 63 10 8 106 124 142 83 8 6 155 165 205 112 6 4 190 220 278 148 4 3 214 252 327 170 3 2 255 293 381 198 2 1 293 344 440 228 1 1/0 339 399 532 263 1/0 2/0 390 467 591 305 2/0 3/0 451 546 708 351 3/0 4/0 529 629 830 411 4/0 Notes: 1. Section 310.15(B) shall be referenced for ampacity correction factors where the ambient temperature is other than 40°C (104°F). 2. Section 310.19 shall be referenced for conditions of use. [310.19](https://2023.antflix.net#310.19)
|
https://2023.antflix.net#310.19
|
Chapter 3 Wiring Methods and Materials
|
310.20
|
The ampacities shall be as specified in Table 310.20 where all of the following conditions apply: (1) Conductors are rated 0 volts through 2000 volts. (2) Conductors are rated 75°C (167°F) or 90°C (194°F). (3) Wiring is installed in a 40°C (104°F) ambient temperature. (4) There are not more than three single-insulated conductors. Table 310.20 Ampacities of Conductors on a Messenger Size AWG or kcmil Temperature Rating of Conductor [See Table 310.4(1)] Size AWG or kcmil 75°C (167°F) 90°C (194°F) 75°C (167°F) 90°C (194°F) Types RHW, THHW, THW, THWN, XHHW, XHWN, ZW Types MI, THHN, THHW, THW-2, THWN-2, RHH, RHW-2, USE-2, XHHW, XHHW-2, XHWN-2, ZW-2 Types RHW, THW, THWN, THHW, XHHW, XHWN Types THHN, THHW, RHH, XHHW, RHW-2, XHHW-2, THW-2, THWN 2, XHWN-2, USE-2, ZW-2 COPPER ALUMINUM OR COPPER-CLAD ALUMINUM 8 57 66 44 51 8 6 76 89 59 69 6 4 101 117 78 91 4 3 118 138 92 107 3 2 135 158 106 123 2 1 158 185 123 144 1 1/0 183 214 143 167 1/0 2/0 212 247 165 193 2/0 3/0 245 287 192 224 3/0 4/0 287 335 224 262 4/0 250 320 374 251 292 250 300 359 419 282 328 300 350 397 464 312 364 350 400 430 503 339 395 400 500 496 580 392 458 500 600 553 647 440 514 600 700 610 714 488 570 700 750 638 747 512 598 750 800 660 773 532 622 800 900 704 826 572 669 900 1000 748 879 612 716 1000 Notes: 1. Section 310.15(B) shall be referenced for ampacity correction factors where the ambient temperature is other than 40°C (104°F). 2. Section 310.15(C)(1) shall be referenced for more than three current-carrying conductors. 3. Section 310.20 shall be referenced for conditions of use. [310.20](https://2023.antflix.net#310.20)
|
https://2023.antflix.net#310.20
|
Chapter 3 Wiring Methods and Materials
|
310.21
|
The ampacities shall be as specified in Table 310.21 where all of the following conditions apply: Wind velocity is 610 mm/sec (2 ft/sec).Conductors are 80°C (176°F) total conductor temperature.Wiring is installed in a 40°C (104°F) ambient temperature.Table 310.21 Ampacities of Bare or Covered Conductors in Free Air Copper Conductors AAC Aluminum Conductors Bare Covered Bare Covered AWG or kcmil Amperes AWG or kcmil Amperes AWG or kcmil Amperes AWG or kcmil Amperes 8 98 8 103 8 76 8 80 6 124 6 130 6 96 6 101 4 155 4 163 4 121 4 127 2 209 2 219 2 163 2 171 1/0 282 1/0 297 1/0 220 1/0 231 2/0 329 2/0 344 2/0 255 2/0 268 3/0 382 3/0 401 3/0 297 3/0 312 4/0 444 4/0 466 4/0 346 4/0 364 250 494 250 519 266.8 403 266.8 423 300 556 300 584 336.4 468 336.4 492 500 773 500 812 397.5 522 397.5 548 750 1000 750 1050 477.0 588 477.0 617 1000 1193 1000 1253 556.5 650 556.5 682 - - - - 636.0 709 636.0 744 - - - - 795.0 819 795.0 860 - - - - 954.0 920 - - - - - - 1033.5 968 1033.5 1017 - - - - 1272 1103 1272 1201 - - - - 1590 1267 1590 1381 - - - - 2000 1454 2000 1527 Note: Section 310.21 shall be referenced for conditions of use. [310.21](https://2023.antflix.net#310.21)
|
https://2023.antflix.net#310.21
|
Chapter 3 Wiring Methods and Materials
|
312.1
|
This article covers the installation and construction specifications of cabinets, cutout boxes, and meter socket enclosures. It does not apply to equipment operating at over 1000 volts, except as specifically referenced elsewhere in the Code. [312.1](https://2023.antflix.net#312.1)
|
https://2023.antflix.net#312.1
|
Chapter 3 Wiring Methods and Materials
|
312.2
|
In damp or wet locations, surface-type enclosures within the scope of this article shall be placed or equipped so as to prevent moisture or water from entering and accumulating within the cabinet or cutout box, and shall be mounted so there is at least 6-mm (1/4-in.) airspace between the enclosure and the wall or other supporting surface. Enclosures installed in wet locations shall be weatherproof. For enclosures in wet locations, raceways or cables entering above the level of uninsulated live parts shall use fittings listed for wet locations. Exception: Nonmetallic enclosures shall be permitted to be installed without the airspace on a concrete, masonry, tile, or similar surface. Informational Note: See 300.6 for protection against corrosion. [312.2](https://2023.antflix.net#312.2)
|
https://2023.antflix.net#312.2
|
Chapter 3 Wiring Methods and Materials
|
312.3
|
In walls of concrete, tile, or other noncombustible material, cabinets shall be installed so that the front edge of the cabinet is not set back of the finished surface more than 6 mm (1/4 in.). In walls constructed of wood or other combustible material, cabinets shall be flush with the finished surface or project therefrom. [312.3](https://2023.antflix.net#312.3)
|
https://2023.antflix.net#312.3
|
Chapter 3 Wiring Methods and Materials
|
312.4
|
Noncombustible surfaces that are broken or incomplete shall be repaired so there will be no gaps or open spaces greater than 3 mm (1/8 in.) at the edge of the cabinet or cutout box employing a flush-type cover. [312.4](https://2023.antflix.net#312.4)
|
https://2023.antflix.net#312.4
|
Chapter 3 Wiring Methods and Materials
|
312.5
|
Cable assemblies and insulated conductors entering enclosures within the scope of this article shall be protected from abrasion and shall comply with 312.5(A) through (C). [312.5](https://2023.antflix.net#312.5)
|
https://2023.antflix.net#312.5
|
Chapter 3 Wiring Methods and Materials
|
312.5(A)
|
Openings through which conductors enter shall be closed in an approved manner. [312.5(A)](https://2023.antflix.net#312.5(A))
|
https://2023.antflix.net#312.5(A)
|
Chapter 3 Wiring Methods and Materials
|
312.5(B)
|
Where metal enclosures within the scope of this article are installed with messenger-supported wiring, open wiring on insulators, or concealed knob-and-tube wiring, conductors shall enter through insulating bushings or, in dry locations, through flexible tubing extending from the last insulating support and firmly secured to the enclosure. [312.5(B)](https://2023.antflix.net#312.5(B))
|
https://2023.antflix.net#312.5(B)
|
Chapter 3 Wiring Methods and Materials
|
312.5(C)
|
Where cable is used, each cable shall be secured to the cabinet, cutout box, or meter socket enclosure. Exception No. 1: Cables with entirely nonmetallic sheaths shall be permitted to enter the top of a surface-mounted enclosure through one or more nonflexible raceways not less than 450 mm (18 in.) and not more than 3.0 m (10 ft) in length, provided all of the following conditions are met: (1) Each cable is fastened within 300 mm (12 in.), measured along the sheath, of the outer end of the raceway. (2) The raceway extends directly above the enclosure and does not penetrate a structural ceiling. (3) A fitting is provided on each end of the raceway to protect the cable(s) from abrasion and the fittings remain accessible after installation. (4) The raceway is sealed or plugged at the outer end using approved means so as to prevent access to the enclosure through the raceway. (5) The cable sheath is continuous through the raceway and extends into the enclosure beyond the fitting not less than 6 mm (1/4 in.). (6) The raceway is fastened at its outer end and at other points in accordance with the applicable article. (7) Where installed as conduit or tubing, the cable fill does not exceed the amount that would be permitted for complete conduit or tubing systems by Table 1 of Chapter 9 of this Code and all applicable notes thereto. Note 2 to the tables in Chapter 9 does not apply to this condition. Informational Note: See Chapter 9, Table 1, including Note 9, for allowable cable fill in circular raceways. See 310.15(C)(1) for required ampacity reductions for multiple cables installed in a common raceway. Exception No. 2: Single conductors and multiconductor cables shall be permitted to enter enclosures in accordance with 392.46(A) or (B). [312.5(C)](https://2023.antflix.net#312.5(C))
|
https://2023.antflix.net#312.5(C)
|
Chapter 3 Wiring Methods and Materials
|
312.6
|
Conductors at terminals or conductors entering or leaving cabinets, cutout boxes, and meter socket enclosures shall comply with 312.6(A) through (C). Exception: Wire-bending space in enclosures for motor controllers with provisions for one or two wires per terminal shall comply with 430.10(B). [312.6](https://2023.antflix.net#312.6)
|
https://2023.antflix.net#312.6
|
Chapter 3 Wiring Methods and Materials
|
312.6(A)
|
Conductors shall not be deflected within a cabinet or cutout box unless a gutter having a width in accordance with Table 312.6(A) is provided. Conductors in parallel in accordance with 310.10(G) shall be judged on the basis of the number of conductors in parallel.
Table 312.6(A) Minimum Wire-Bending Space at Terminals and Minimum Width of Wiring Gutters
Wire Size (AWG or kcmil)
Wires per Terminal
All Other Conductors
Compact Stranded AA-8000 AluminumAlloy Conductors (See Note 2)
1
2
3
4
5
mm
in.
mm
in.
mm
in.
mm
in.
mm
in.
14—10
12—8
Not specified
-
-
-
-
-
-
-
-
8—6
6—4
38.1
11/2
-
-
-
-
-
-
-
-
4—3
2—1
50.8
2
-
-
-
-
-
-
-
-
2
1/0
63.5
21/2
-
-
-
-
-
-
-
-
1
2/0
76.2
3
-
-
-
-
-
-
-
-
1/0—2/0
3/0—4/0
88.9
31/2
127
5
178
7
-
-
-
-
3/0—4/0
250—300
102
4
152
6
203
8
-
-
-
-
250
350
114
41/2
152
6
203
8
254
10
-
-
300—350
400—500
127
5
203
8
254
10
305
12
-
-
400—500
600—750
152
6
203
8
254
10
305
12
356
14
600—700
800—1000
203
8
254
10
305
12
356
14
406
16
750—900
-
203
8
305
12
356
14
406
16
457
18
1000—1250
-
254
10
-
-
-
-
-
-
-
-
1500—2000
-
305
12
-
-
-
-
-
-
-
-
Notes:
1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector (in the direction that the wire leaves the terminal) to the wall, barrier, or obstruction.
2. This column shall be permitted to be used to determine the minimum wire-bending space for compact stranded aluminum conductors in sizes up to 1000 kcmil and manufactured using AA-8000 series electrical grade aluminum alloy conductor material in accordance with 310.3(B). The minimum width of the wire gutter space shall be determined using the all other conductors value in this table.
[312.6(A)](https://2023.antflix.net#312.6(A))
|
https://2023.antflix.net#312.6(A)
|
Chapter 3 Wiring Methods and Materials
|
312.6(B)
|
Wire-bending space at each terminal shall be provided in accordance with 312.6(B)(1) or (B)(2). [312.6(B)](https://2023.antflix.net#312.6(B))
|
https://2023.antflix.net#312.6(B)
|
Chapter 3 Wiring Methods and Materials
|
312.6(B)(1)
|
Table 312.6(A) shall apply where the conductor does not enter or leave the enclosure through the wall opposite its terminal. [312.6(B)(1)](https://2023.antflix.net#312.6(B)(1))
|
https://2023.antflix.net#312.6(B)(1)
|
Chapter 3 Wiring Methods and Materials
|
312.6(B)(2)
|
Table 312.6(B)(2) shall apply where the conductor does enter or leave the enclosure through the wall opposite its terminal.
Exception No. 1: Where the distance between the wall and its terminal is in accordance with Table 312.6(A), a conductor shall be permitted to enter or leave an enclosure through the wall opposite its terminal, provided the conductor enters or leaves the enclosure where the gutter joins an adjacent gutter that has a width that conforms to Table 312.6(B)(2) for the conductor.
Exception No. 2: A conductor not larger than 350 kcmil shall be permitted to enter or leave an enclosure containing only a meter socket(s) through the wall opposite its terminal, provided the distance between the terminal and the opposite wall is not less than that specified in Table 312.6(A) and the terminal is a lay-in type or removable lug with integral mounting tang, where the terminal is either of the following:
(1) Directed toward the opening in the enclosure and within a 45-degree angle of directly facing the enclosure wall
(2) Directly facing the enclosure wall and offset not greater than 50 percent of the bending space specified in Table 312.6(A)
Informational Note: Offset is the distance measured along the enclosure wall from the axis of the centerline of the terminal to a line passing through the center of the opening in the enclosure.
Table 312.6(B)(2) Minimum Wire-Bending Space at Terminals
Wire Size (AWG or kcmil)
Wires per Terminal
All Other Conductors
Compact StrandedAA-8000 Aluminum Alloy Conductors(See Note 3)
1
2
3
4 or more
mm
in.
mm
in.
mm
in.
mm
in.
14—10
12—8
Not specified
-
-
-
-
-
8
6
38.1
11/2
-
-
-
-
-
6
4
50.8
2
-
-
-
-
-
4
2
76.2
3
-
-
-
-
-
3
1
76.2
3
-
-
-
-
-
2
1/0
88.9
31/2
-
-
-
-
-
1
2/0
114
41/2
-
-
-
-
-
1/0
3/0
140
51/2
140
51/2
178
7
-
-
2/0
4/0
152
6
152
6
190
71/2
-
-
3/0
250
165a
61/2a
165a
61/2a
203
8
-
-
4/0
300
178b
7b
190c
71/2c
216a
81/2a
-
-
250
350
216d
81/2d
216d
81/2d
229b
9b
254
10
300
400
254e
10e
254d
10d
279b
11b
305
12
350
500
305e
12e
305e
12e
330e
13e
356d
14d
400
600
330e
13e
330e
13e
356e
14e
381e
15e
500
700—750
356e
14e
356e
14e
381e
15e
406e
16e
600
800—900
381e
15e
406e
16e
457e
18e
483e
19e
700
1000
406e
16e
457e
18e
508e
20e
559e
22e
750
-
432e
17e
483e
19e
559e
22e
610e
24e
800
-
457
18
508
20
559
22
610
24
900
-
483
19
559
22
610
24
610
24
1000
-
508
20
-
-
-
-
1250
-
559
22
-
-
-
-
1500
-
610
24
-
-
-
-
1750
-
610
24
-
-
-
-
2000
—
610
24
-
-
-
-
Notes:
1. Bending space at terminals shall be measured in a straight line from the end of the lug or wire connector in a direction perpendicular to the enclosure wall.
2. For removable and lay-in wire terminals intended for only one wire, bending space shall be permitted to be reduced by the following number of millimeters (inches):
a12.7 mm (1/2 in.)
b25.4 mm (1 in.)
c38.1 mm (11/2 in.)
d50.8 mm (2 in.)
e76.2 mm (3 in.)
3. This column shall be permitted to determine the required wire-bending space for compact stranded aluminum conductors in sizes up to 1000 kcmil and manufactured using AA-8000 series electrical grade aluminum alloy conductor material in accordance with 310.3(B). [312.6(B)(2)](https://2023.antflix.net#312.6(B)(2))
|
https://2023.antflix.net#312.6(B)(2)
|
Chapter 3 Wiring Methods and Materials
|
312.6(C)
|
Installation shall comply with 300.4(G). [312.6(C)](https://2023.antflix.net#312.6(C))
|
https://2023.antflix.net#312.6(C)
|
Chapter 3 Wiring Methods and Materials
|
312.7
|
Cabinets and cutout boxes shall have approved space to accommodate all conductors installed in them without crowding. [312.7](https://2023.antflix.net#312.7)
|
https://2023.antflix.net#312.7
|
Chapter 3 Wiring Methods and Materials
|
312.8
|
The wiring space within enclosures for switches and overcurrent devices shall be permitted for other wiring and equipment subject to limitations for specific equipment as provided in 312.8(A) and (B). [312.8](https://2023.antflix.net#312.8)
|
https://2023.antflix.net#312.8
|
Chapter 3 Wiring Methods and Materials
|
312.8(A)
|
The wiring space of enclosures for switches or overcurrent devices shall be permitted for conductors feeding through, spliced, or tapping off to other enclosures, switches, or overcurrent devices where all of the following conditions are met: The total of all conductors installed at any cross section of the wiring space does not exceed 40 percent of the cross-sectional area of that space.The total area of all conductors, splices, and taps installed at any cross section of the wiring space does not exceed 75 percent of the cross-sectional area of that space.The bending space for conductors 4 AWG and larger complies with 314.28(A)(2).A warning label complying with 110.21(B) is applied to the enclosure that identifies the closest disconnecting means for any feed-through conductors. [312.8(A)](https://2023.antflix.net#312.8(A))
|
https://2023.antflix.net#312.8(A)
|
Chapter 3 Wiring Methods and Materials
|
312.8(B)
|
The wiring space of enclosures for switches or overcurrent devices shall be permitted to contain power monitoring or energy management equipment in accordance with 312.8(B)(1) through (B)(3). [312.8(B)](https://2023.antflix.net#312.8(B))
|
https://2023.antflix.net#312.8(B)
|
Chapter 3 Wiring Methods and Materials
|
312.8(B)(1)
|
Power monitoring or energy management equipment shall either be identified as a field installable accessory as part of the listed equipment or be a listed kit evaluated for field installation in switch or overcurrent device enclosures. [312.8(B)(1)](https://2023.antflix.net#312.8(B)(1))
|
https://2023.antflix.net#312.8(B)(1)
|
Chapter 3 Wiring Methods and Materials
|
312.8(B)(2)
|
The total area of all conductors, splices, taps, and equipment at any cross section of the wiring space shall not exceed 75 percent of the cross-sectional area of that space. [312.8(B)(2)](https://2023.antflix.net#312.8(B)(2))
|
https://2023.antflix.net#312.8(B)(2)
|
Chapter 3 Wiring Methods and Materials
|
312.8(B)(3)
|
Conductors used exclusively for control or instrumentation circuits shall comply with either 312.8(B)(3)(a) or (B)(3)(b). Conductors shall comply with 724.49.Conductors smaller than 18 AWG, but not smaller than 22 AWG for a single conductor and 26 AWG for a multiconductor cable, shall be permitted to be used where the conductors and cable assemblies meet all of the following conditions:Are enclosed within raceways or routed along one or more walls of the enclosure and secured at intervals that do not exceed 250 mm (10 in.)Are secured within 250 mm (10 in.) of terminationsAre secured to prevent contact with current carrying components within the enclosureAre rated for the system voltage and not less than 600 voltsHave a minimum insulation temperature rating of 90°C [312.8(B)(3)](https://2023.antflix.net#312.8(B)(3))
|
https://2023.antflix.net#312.8(B)(3)
|
Chapter 3 Wiring Methods and Materials
|
312.9
|
Cabinets and cutout boxes shall be provided with back-wiring spaces, gutters, or wiring compartments as required by 312.101(C) and (D). [312.9](https://2023.antflix.net#312.9)
|
https://2023.antflix.net#312.9
|
Chapter 3 Wiring Methods and Materials
|
312.10
|
Screws or other fasteners installed in the field that enter wiring spaces shall be as provided by or specified by the manufacturer or shall comply with the following as applicable: Screws shall be machine type with blunt ends.Other fasteners shall have blunt ends.Screws or other fasteners shall extend into the enclosure no more than 6 mm (1/4 in.) unless the end is protected with an approved means.Exception to (3): Screws or other fasteners shall be permitted to extend into the enclosure not more than 11 mm (7/16 in.) if located within 10 mm (3/8 in.) of an enclosure wall. [312.10](https://2023.antflix.net#312.10)
|
https://2023.antflix.net#312.10
|
Chapter 3 Wiring Methods and Materials
|
312.100
|
Cabinets, cutout boxes, and meter socket enclosures shall comply with 312.100(A) through (C). [312.100](https://2023.antflix.net#312.100)
|
https://2023.antflix.net#312.100
|
Chapter 3 Wiring Methods and Materials
|
312.100(A)
|
Metal enclosures within the scope of this article shall be protected both inside and outside against corrosion. [312.100(A)](https://2023.antflix.net#312.100(A))
|
https://2023.antflix.net#312.100(A)
|
Chapter 3 Wiring Methods and Materials
|
312.100(B)
|
The design and construction of enclosures within the scope of this article shall be such as to secure ample strength and rigidity. If constructed of sheet steel, the metal thickness shall not be less than 1.35 mm (0.053 in.) uncoated. [312.100(B)](https://2023.antflix.net#312.100(B))
|
https://2023.antflix.net#312.100(B)
|
Chapter 3 Wiring Methods and Materials
|
312.100(C)
|
Nonmetallic cabinets shall be listed, or they shall be submitted for approval prior to installation. [312.100(C)](https://2023.antflix.net#312.100(C))
|
https://2023.antflix.net#312.100(C)
|
Chapter 3 Wiring Methods and Materials
|
312.101
|
The spacing within cabinets and cutout boxes shall comply with 312.101(A) through (D). [312.101](https://2023.antflix.net#312.101)
|
https://2023.antflix.net#312.101
|
Chapter 3 Wiring Methods and Materials
|
312.101(A)
|
Spacing within cabinets and cutout boxes shall provide approved spacing for the distribution of wires and cables placed in them and for a separation between metal parts of devices and apparatus mounted within them in accordance with 312.101(A)(1), (A)(2), and (A)(3). [312.101(A)](https://2023.antflix.net#312.101(A))
|
https://2023.antflix.net#312.101(A)
|
Chapter 3 Wiring Methods and Materials
|
312.101(A)(1)
|
Other than at points of support, there shall be an airspace of at least 1.59 mm (0.0625 in.) between the base of the device and the wall of any metal cabinet or cutout box in which the device is mounted. [312.101(A)(1)](https://2023.antflix.net#312.101(A)(1))
|
https://2023.antflix.net#312.101(A)(1)
|
Chapter 3 Wiring Methods and Materials
|
312.101(A)(2)
|
There shall be an airspace of at least 25.4 mm (1.00 in.) between any live metal part, including live metal parts of enclosed fuses, and the door. Exception: Where the door is lined with an approved insulating material or is of a thickness of metal not less than 2.36 mm (0.093 in.) uncoated, the airspace shall not be less than 12.7 mm (0.500 in.). [312.101(A)(2)](https://2023.antflix.net#312.101(A)(2))
|
https://2023.antflix.net#312.101(A)(2)
|
Chapter 3 Wiring Methods and Materials
|
312.101(A)(3)
|
There shall be an airspace of at least 12.7 mm (0.500 in.) between the walls, back, gutter partition, if of metal, or door of any cabinet or cutout box and the nearest exposed current-carrying part of devices mounted within the cabinet where the voltage does not exceed 250. This spacing shall be increased to at least 25.4 mm (1.00 in.) for voltages of 251 to 1000, nominal. Exception: Where the conditions in 312.101(A)(2), Exception, are met, the airspace for nominal voltages from 251 to 600 shall be permitted to be not less than 12.7 mm (0.500 in.). [312.101(A)(3)](https://2023.antflix.net#312.101(A)(3))
|
https://2023.antflix.net#312.101(A)(3)
|
Chapter 3 Wiring Methods and Materials
|
312.101(B)
|
Cabinets and cutout boxes shall be deep enough to allow the closing of the doors when 30-ampere branch-circuit panelboard switches are in any position, when combination cutout switches are in any position, or when other single-throw switches are opened as far as their construction permits. [312.101(B)](https://2023.antflix.net#312.101(B))
|
https://2023.antflix.net#312.101(B)
|
Chapter 3 Wiring Methods and Materials
|
312.101(C)
|
Cabinets and cutout boxes that contain devices or apparatus connected within the cabinet or box to more than eight conductors, including those of branch circuits, meter loops, feeder circuits, power circuits, and similar circuits, but not including the supply circuit or a continuation thereof, shall have back-wiring spaces or one or more side-wiring spaces, side gutters, or wiring compartments. [312.101(C)](https://2023.antflix.net#312.101(C))
|
https://2023.antflix.net#312.101(C)
|
Chapter 3 Wiring Methods and Materials
|
312.101(D)
|
Side-wiring spaces, side gutters, or side-wiring compartments of cabinets and cutout boxes shall be made tight enclosures by means of covers, barriers, or partitions extending from the bases of the devices contained in the cabinet, to the door, frame, or sides of the cabinet. Exception: Side-wiring spaces, side gutters, and side-wiring compartments of cabinets shall not be required to be made tight enclosures where those side spaces contain only conductors that enter the cabinet directly opposite to the devices where they terminate. Partially enclosed back-wiring spaces shall be provided with covers to complete the enclosure. Wiring spaces that are required by 312.101(C) and are exposed when doors are open shall be provided with covers to complete the enclosure. Where space is provided for feed-through conductors and for splices as required in 312.8, additional barriers shall not be required. [312.101(D)](https://2023.antflix.net#312.101(D))
|
https://2023.antflix.net#312.101(D)
|
Chapter 3 Wiring Methods and Materials
|
312.102
|
Cabinets, cutout boxes, and meter socket enclosures shall be equipped with doors or covers. [312.102](https://2023.antflix.net#312.102)
|
https://2023.antflix.net#312.102
|
Chapter 3 Wiring Methods and Materials
|
314.1
|
This article covers the installation and use of all boxes and conduit bodies used as outlet, device, junction, or pull boxes, depending on their use, and handhole enclosures. Cast metal, sheet metal, nonmetallic, and other boxes such as FS, FD, and larger boxes are not classified as conduit bodies. This article also includes installation requirements for fittings used to join raceways and to connect raceways and cables to boxes and conduit bodies. [314.1](https://2023.antflix.net#314.1)
|
https://2023.antflix.net#314.1
|
Chapter 3 Wiring Methods and Materials
|
314.2
|
Round boxes shall not be used where conduits or connectors requiring the use of locknuts or bushings are to be connected to the side of the box. [314.2](https://2023.antflix.net#314.2)
|
https://2023.antflix.net#314.2
|
Chapter 3 Wiring Methods and Materials
|
314.3
|
Nonmetallic boxes shall be permitted only with open wiring on insulators, concealed knob-and-tube wiring, cabled wiring methods with entirely nonmetallic sheaths, flexible cords, and nonmetallic raceways. Exception No. 1: Where internal bonding means are provided between all entries, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables. Exception No. 2: Where integral bonding means with a provision for attaching an equipment bonding jumper inside the box are provided between all threaded entries in nonmetallic boxes listed for the purpose, nonmetallic boxes shall be permitted to be used with metal raceways or metal-armored cables. [314.3](https://2023.antflix.net#314.3)
|
https://2023.antflix.net#314.3
|
Chapter 3 Wiring Methods and Materials
|
314.4
|
Metal boxes shall be grounded and bonded in accordance with Parts I, IV, V, VI, VII, and X of Article 250 as applicable, except as permitted in 250.112(I). [314.4](https://2023.antflix.net#314.4)
|
https://2023.antflix.net#314.4
|
Chapter 3 Wiring Methods and Materials
|
314.5
|
Screws or other fasteners installed in the field that enter wiring spaces shall be as provided by or specified by the manufacturer or shall comply with the following as applicable: Screws shall be machine type with blunt ends.Other fasteners shall have blunt ends.Screws attaching a cover shall extend no more than 10 mm (3/8 in.).Screws or other fasteners, other than in (3), penetrating a cover shall extend no more than 8 mm (5/16 in.).Screws or other fasteners penetrating a wall of a box exceeding 1650 cm3 (100 in.3) shall extend no more than 6 mm (1/4 in.), or more than 11 mm (7/16 in.) if located within 10 mm (3/8 in.) of an adjacent box wall.Screws or other fasteners penetrating the wall of a box not exceeding 1650 cm3 (100 in.3) and not covered in 314.23(B)(1) shall be made flush with the box interior.Screws or other fasteners penetrating the wall of a conduit body shall be made flush with the conduit body interior.Exception to (3) through (6): A screw shall be permitted to be longer if the end of the screw is protected with an approved means. [314.5](https://2023.antflix.net#314.5)
|
https://2023.antflix.net#314.5
|
Chapter 3 Wiring Methods and Materials
|
314.15
|
In damp or wet locations, boxes, conduit bodies, outlet box hoods, and fittings shall be placed or equipped so as to prevent moisture from entering or accumulating within the box, conduit body, or fitting. Boxes, conduit bodies, outlet box hoods, and fittings installed in wet locations shall be listed for use in wet locations. Approved drainage openings not smaller than 3 mm (1/8 in.) and not larger than 6 mm (1/4 in.) in diameter shall be permitted to be installed in the field in boxes or conduit bodies listed for use in damp or wet locations. For installation of listed drain fittings, larger openings are permitted to be installed in the field in accordance with manufacturer's instructions. Informational Note No. 1: See 314.27(B) for boxes in floors. Informational Note No. 2: See 300.6 for protection against corrosion. [314.15](https://2023.antflix.net#314.15)
|
https://2023.antflix.net#314.15
|
Chapter 3 Wiring Methods and Materials
|
314.16
|
Boxes and conduit bodies shall be of an approved size to provide free space for all enclosed conductors. In no case shall the volume of the box, as calculated in 314.16(A), be less than the fill calculation as calculated in 314.16(B). The minimum volume for conduit bodies shall be as calculated in 314.16(C). This section shall not apply to terminal housings supplied with motors or generators. Informational Note: See 430.12 for volume requirements of motor or generator terminal housings. Boxes and conduit bodies enclosing conductors 4 AWG or larger shall also comply with 314.28. Outlet and device boxes shall also comply with 314.24. [314.16](https://2023.antflix.net#314.16)
|
https://2023.antflix.net#314.16
|
Chapter 3 Wiring Methods and Materials
|
314.16(A)
|
The volume of a wiring enclosure (box) shall be the total volume of the assembled sections and, where used, the space provided by plaster rings, domed covers, extension rings, and so forth, that are marked with their volume or are made from boxes the dimensions of which are listed in Table 314.16(A). Where a box is provided with one or more securely installed barriers, the volume shall be apportioned to each of the resulting spaces. Each barrier, if not marked with its volume, shall be considered to take up 8.2 cm3 (1/2 in.3) if metal, and 16.4 cm3 (1.0 in.3) if nonmetallic.
Table 314.16(A) Metal Boxes
Box Trade Size
Minimum Volume
Maximum Number of Conductors* (arranged by AWG size)
mm
in.
cm3
in.3
18
16
14
12
10
8
6
100 × 32
(4 × 11/4)
round/octagonal
205
12.5
8
7
6
5
5
4
2
100 × 38
(4 × 11/2)
round/octagonal
254
15.5
10
8
7
6
6
5
3
100 × 54
(4 × 21/8)
round/octagonal
353
21.5
14
12
10
9
8
7
4
100 × 32
(4 × 11/4)
square
295
18.0
12
10
9
8
7
6
3
100 × 38
(4 × 11/2)
square
344
21.0
14
12
10
9
8
7
4
100 × 54
(4 × 21/8)
square
497
30.3
20
17
15
13
12
10
6
120 × 32
(411/16× 11/4)
square
418
25.5
17
14
12
11
10
8
5
120 × 38
(411/16× 11/2)
square
484
29.5
19
16
14
13
11
9
5
120 × 54
(411/16× 21/8)
square
689
42.0
28
24
21
18
16
14
8
75 × 50 × 38
(3 × 2 × 11/2)
device
123
7.5
5
4
3
3
3
2
1
75 × 50 × 50
(3 × 2 × 2)
device
164
10.0
6
5
5
4
4
3
2
75 × 50 × 57
(3 × 2 × 21/4)
device
172
10.5
7
6
5
4
4
3
2
75 × 50 × 65
(3 × 2 × 21/4)
device
205
12.5
8
7
6
5
5
4
2
75 × 50 × 70
(3 × 2 × 23/4)
device
230
14.0
9
8
7
6
5
4
2
75 × 50 × 90
(3 × 2 × 31/2)
device
295
18.0
12
10
9
8
7
6
3
100 × 54 × 38
(4 × 21/8 × 11/2)
device
169
10.3
6
5
5
4
4
3
2
100 × 54 × 48
(4 × 21/8 × 17/8)
device
213
13.0
8
7
6
5
5
4
2
100 × 54 × 54
(4 × 21/8 × 21/8)
device
238
14.5
9
8
7
6
5
4
2
95 × 50 × 65
(33/4 × 2 × 21/2)
masonry box/gang
230
14.0
9
8
7
6
5
4
2
95 × 50 × 90
(33/4 × 2 × 31/2)
masonry box/gang
344
21.0
14
12
10
9
8
7
4
min. 44.5 depth
FS - single cover/gang (13/4)
221
13.5
9
7
6
6
5
4
2
min. 60.3 depth
FD - single cover/gang (23/8)
295
18.0
12
10
9
8
7
6
3
min. 44.5 depth
FS - multiple cover/gang (13/4)
295
18.0
12
10
9
8
7
6
3
min. 60.3 depth
FD - multiple cover/gang (23/8)
395
24.0
16
13
12
10
9
8
4
*Where no volume allowances are required by 314.16(B)(2) through (B)(6). [314.16(A)](https://2023.antflix.net#314.16(A))
|
https://2023.antflix.net#314.16(A)
|
Chapter 3 Wiring Methods and Materials
|
314.16(A)(1)
|
The volumes of standard boxes that are not marked with their volume shall be as given in Table 314.16(A). [314.16(A)(1)](https://2023.antflix.net#314.16(A)(1))
|
https://2023.antflix.net#314.16(A)(1)
|
Chapter 3 Wiring Methods and Materials
|
314.16(A)(2)
|
Boxes 1650 cm3 (100 in.3) or less, other than those described in Table 314.16(A), and nonmetallic boxes shall be durably and legibly marked by the manufacturer with their volume(s). Boxes described in Table 314.16(A) that have a volume larger than is designated in the table shall be permitted to have their volume marked as required by this section. [314.16(A)(2)](https://2023.antflix.net#314.16(A)(2))
|
https://2023.antflix.net#314.16(A)(2)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)
|
The volumes in 314.16(B)(1) through (B)(6), as applicable, shall be added together. No allowance shall be required for small fittings such as locknuts and bushings. Each space within a box installed with a barrier shall be calculated separately. [314.16(B)](https://2023.antflix.net#314.16(B))
|
https://2023.antflix.net#314.16(B)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)(1)
|
Each conductor that originates outside the box and terminates or is spliced within the box shall be counted once, and each conductor that passes through the box without splice or termination shall be counted once. Each loop or coil of unbroken conductor not less than twice the minimum length required for free conductors in 300.14 shall be counted twice. The conductor fill shall be calculated using Table 314.16(B)(1). A conductor, no part of which leaves the box, shall not be counted.
Exception: An equipment grounding conductor or conductors or not over four fixture wires smaller than 14 AWG, or both, shall be permitted to be omitted from the calculations where they enter a box from a domed luminaire or similar canopy and terminate within that box.
Table 314.16(B)(1) Volume Allowance Required per Conductor
Size of Conductor (AWG)
Free Space Within Box for Each Conductor
cm3
in.3
18
24.6
1.50
16
28.7
1.75
14
32.8
2.00
12
36.9
2.25
10
41.0
2.50
8
49.2
3.00
6
81.9
5.00
[314.16(B)(1)](https://2023.antflix.net#314.16(B)(1))
|
https://2023.antflix.net#314.16(B)(1)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)(2)
|
Where one or more internal cable clamps, whether factory or field supplied, are present in the box, a single volume allowance in accordance with Table 314.16(B)(1) shall be made based on the largest conductor present in the box. No allowance shall be required for a cable connector with its clamping mechanism outside the box. [314.16(B)(2)](https://2023.antflix.net#314.16(B)(2))
|
https://2023.antflix.net#314.16(B)(2)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)(3)
|
Where one or more luminaire studs or hickeys are present in the box, a single volume allowance in accordance with Table 314.16(B)(1) shall be made for each type of fitting based on the largest conductor present in the box. [314.16(B)(3)](https://2023.antflix.net#314.16(B)(3))
|
https://2023.antflix.net#314.16(B)(3)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)(4)
|
For each yoke or strap containing one or more devices or equipment, a double volume allowance in accordance with Table 314.16(B)(1) shall be made for each yoke or strap based on the largest conductor connected to a device(s) or equipment supported by that yoke or strap. A device or utilization equipment wider than a single 50 mm (2 in.) device box as described in Table 314.16(A) shall have double volume allowances provided for each gang required for mounting. [314.16(B)(4)](https://2023.antflix.net#314.16(B)(4))
|
https://2023.antflix.net#314.16(B)(4)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)(5)
|
Where up to four equipment grounding conductors enter a box, a single volume allowance in accordance with Table 314.16(B)(1) shall be made based on the largest equipment grounding conductor entering the box. A 1/4 volume allowance shall be made for each additional equipment grounding conductor that enters the box, based on the largest equipment grounding conductor entering the box. [314.16(B)(5)](https://2023.antflix.net#314.16(B)(5))
|
https://2023.antflix.net#314.16(B)(5)
|
Chapter 3 Wiring Methods and Materials
|
314.16(B)(6)
|
Where a terminal block is present in a box, a single volume allowance in accordance with Table 314.16(B)(1) shall be made for each terminal block assembly based on the largest conductor(s) terminated to the assembly. [314.16(B)(6)](https://2023.antflix.net#314.16(B)(6))
|
https://2023.antflix.net#314.16(B)(6)
|
Chapter 3 Wiring Methods and Materials
|
314.16(C)(1)
|
Conduit bodies enclosing 6 AWG conductors or smaller, other than short-radius conduit bodies as described in 314.16(C)(3). shall have a cross-sectional area not less than twice the cross-sectional area of the largest conduit or tubing to which they can be attached. The maximum number of conductors permitted shall be the maximum number permitted by Table 1 of Chapter 9 for the conduit or tubing to which it is attached. [314.16(C)(1)](https://2023.antflix.net#314.16(C)(1))
|
https://2023.antflix.net#314.16(C)(1)
|
Chapter 3 Wiring Methods and Materials
|
314.16(C)(2)
|
Only those conduit bodies that are durably and legibly marked by the manufacturer with their volume shall be permitted to contain splices, taps, or devices. The maximum number of conductors shall be calculated in accordance with 314.16(B). Conduit bodies shall be supported in a rigid and secure manner. [314.16(C)(2)](https://2023.antflix.net#314.16(C)(2))
|
https://2023.antflix.net#314.16(C)(2)
|
Chapter 3 Wiring Methods and Materials
|
314.16(C)(3)
|
Conduit bodies such as capped elbows and service-entrance elbows that enclose conductors 6 AWG or smaller, and are only intended to enable the installation of the raceway and the contained conductors, shall not contain splices, taps, or devices and shall be of an approved size to provide free space for all conductors enclosed in the conduit body. [314.16(C)(3)](https://2023.antflix.net#314.16(C)(3))
|
https://2023.antflix.net#314.16(C)(3)
|
Chapter 3 Wiring Methods and Materials
|
314.17
|
Conductors entering boxes, conduit bodies, or fittings shall be protected from abrasion. Conductors and cables shall comply with 314.17(A) through (C). [314.17](https://2023.antflix.net#314.17)
|
https://2023.antflix.net#314.17
|
Chapter 3 Wiring Methods and Materials
|
314.17(A)
|
Openings through which conductors enter shall be closed in an approved manner. [314.17(A)](https://2023.antflix.net#314.17(A))
|
https://2023.antflix.net#314.17(A)
|
Chapter 3 Wiring Methods and Materials
|
314.17(B)
|
The installation of the conductors and cables in boxes and conduit bodies shall comply with 314.17(B)(1) through (B)(4). [314.17(B)](https://2023.antflix.net#314.17(B))
|
https://2023.antflix.net#314.17(B)
|
Chapter 3 Wiring Methods and Materials
|
314.17(B)(1)
|
For messenger-supported wiring, open wiring on insulators, or concealed knob-and-tube wiring, the conductors shall enter the box through individual holes. In installations where metal boxes or conduit bodies are used with conductors unprotected by flexible tubing, the individual openings shall be provided with insulating bushings. Where flexible tubing is used to enclose the conductors, the tubing shall extend from the last insulating support to not less than 6 mm (1/4 in.) inside the box or conduit body and 6 mm (1/4 in.) beyond the end of any cable clamp. The wiring method shall be secured to the box or conduit body. [314.17(B)(1)](https://2023.antflix.net#314.17(B)(1))
|
https://2023.antflix.net#314.17(B)(1)
|
Chapter 3 Wiring Methods and Materials
|
314.17(B)(2)
|
Where cable assemblies with nonmetallic sheaths are used, the sheath shall extend not less than 6 mm (1/4 in.) inside the box and 6 mm (1/4 in.) beyond the end of any cable clamp. Except as covered in 300.15(C), the wiring method shall be secured to the box or conduit body. Exception: Where nonmetallic-sheathed cable is used with single gang nonmetallic boxes not larger than a nominal size 57 mm × 100 mm (21/4 in. × 4 in.) mounted in walls or ceilings, and where the cable is fastened within 200 mm (8 in.) of the box measured along the sheath and where the sheath extends through a cable knockout not less than 6 mm (1/4 in.), securing the cable to the box shall not be required. Multiple cable entries shall be permitted in a single cable knockout opening. [314.17(B)(2)](https://2023.antflix.net#314.17(B)(2))
|
https://2023.antflix.net#314.17(B)(2)
|
Chapter 3 Wiring Methods and Materials
|
314.17(B)(3)
|
Where the raceway is complete between boxes, conduit bodies, or both and encloses individual conductors or nonmetallic cable assemblies or both, the conductors or cable assemblies shall not be required to be additionally secured. Where raceways enclose cable assemblies as covered in 300.15(C), the cable assembly shall not be required to be additionally secured within the box or conduit body. [314.17(B)(3)](https://2023.antflix.net#314.17(B)(3))
|
https://2023.antflix.net#314.17(B)(3)
|
Chapter 3 Wiring Methods and Materials
|
314.17(B)(4)
|
Nonmetallic boxes and conduit bodies shall be suitable for the lowest temperature-rated conductor entering the box or conduit body. [314.17(B)(4)](https://2023.antflix.net#314.17(B)(4))
|
https://2023.antflix.net#314.17(B)(4)
|
Chapter 3 Wiring Methods and Materials
|
314.17(C)
|
Installation shall comply with 300.4(G). Informational Note: See 110.12(A) for requirements on closing unused cable and raceway knockout openings. [314.17(C)](https://2023.antflix.net#314.17(C))
|
https://2023.antflix.net#314.17(C)
|
Chapter 3 Wiring Methods and Materials
|
314.19
|
Boxes used to enclose flush devices or flush equipment shall be of such design that the devices or equipment will be completely enclosed on the back and sides, and substantial support for the devices or equipment will be provided. Screws for supporting the box shall not also be used to attach a device or equipment. [314.19](https://2023.antflix.net#314.19)
|
https://2023.antflix.net#314.19
|
Chapter 3 Wiring Methods and Materials
|
314.20
|
Installations within or behind a surface of concrete, tile, gypsum, plaster, or other noncombustible material, including boxes employing a flush-type cover or faceplate, shall be made so that the front edge of the box, plaster ring, extension ring, or listed extender will not be set back of the finished surface more than 6 mm (1/4 in.). Installations within a surface of wood or other combustible surface material, boxes, plaster rings, extension rings, or listed extenders shall extend to the finished surface or project therefrom. [314.20](https://2023.antflix.net#314.20)
|
https://2023.antflix.net#314.20
|
Chapter 3 Wiring Methods and Materials
|
314.21
|
Noncombustible surfaces that are broken or incomplete around boxes employing a flush-type cover or faceplate shall be repaired so there will be no gaps or open spaces greater than 3 mm (1/8 in.) at the edge of the box. [314.21](https://2023.antflix.net#314.21)
|
https://2023.antflix.net#314.21
|
Chapter 3 Wiring Methods and Materials
|
314.22
|
Surface extensions shall be made by mounting and mechanically securing an extension ring over the box. Equipment grounding shall be in accordance with Part VI of Article 250. Exception: A surface extension shall be permitted to be made from the cover of a box where the cover is designed so it is unlikely to fall off or be removed if its securing means becomes loose. The wiring method shall be flexible for an approved length that permits removal of the cover and provides access to the box interior and shall be arranged so that any grounding continuity is independent of the connection between the box and cover. [314.22](https://2023.antflix.net#314.22)
|
https://2023.antflix.net#314.22
|
Chapter 3 Wiring Methods and Materials
|
314.23
|
Enclosures within the scope of this article shall be supported in accordance with 314.23(A) through (H) as applicable. [314.23](https://2023.antflix.net#314.23)
|
https://2023.antflix.net#314.23
|
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