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392.22(A)(6). Where more than one multiconductor cable is instal⁠led, the sum of the cross-sectional area of all cable shall not exceed the value specified in Column 2 of Table 392.22(A)(6). Table 392.22(A)(6) Allowable Cable Fill Area for Multiconductor Cables in Solid Channel Cable Trays for C...

392.22(A)(6). Where more than one multiconductor cable is instal⁠led, the sum of the cross-sectional area of all cable shall not exceed the value specified in Column 2 of Table 392.22(A)(6). Table 392.22(A)(6) Allowable Cable Fill Area for Multiconductor Cables in Solid Channel Cable Trays for Cables Rated 2000 Volts or Less Inside Width of Cable Tray Column 1 One Cable Column 2 More Than One Cable mm in. mm2 in.2 mm2 in.2 50 2 850 1.3 500 0.8 75 3 1300 2.0 700 1.1 100 4 2400 3.7 1400 2.1 150 6 3600 5.5 2100 3.2 (B) Number of Single-Conductor Cables, Rated 2000 Volts or Less, in Cable Trays. The number of single conductor cables, rated 2000 volts or less, permitted in a single cable tray section shall not exceed the requirements of this section. The single conductors, or conductor assemblies, shall be evenly distributed across the cable tray. The conductor sizes shall apply to both aluminum and copper conductors. Ladder or Ventilated Trough Cable Trays. Where ladder or ventilated trough cable trays contain single-conductor cables, the maximum number of single conductors shall conform to 392.22(B)(1)(a) through (B)(1)(d). Where all of the cables are 1000 kcmil or larger, the sum of the diameters of all single-conductor cables shall not exceed the cable tray width, and the cables shall be installed in a single layer. Conductors that are bound together to comprise each circuit group shall be permitted to be installed in other than a single layer. Where all of the cables are from 250 kcmil through 900 kcmil, the sum of the cross-sectional areas of all single-conductor cables shall not exceed the maximum allowable cable fill area in Column 1 of Table 392.22(B)(1) for the appropriate cable tray width. Where 1000 kcmil or larger single-conductor cables are installed in the same cable tray with single-conductor cables smaller than 1000 kcmil, the sum of the cross sectional areas of all cables smaller than 1000 kcmil shall not exceed the maximum allowable fill area resulting from the computation in Column 2 of Table 392.22(B)(1) for the appropriate cable tray width. Where any of the single conductor cables are 1/0 through 4/0 AWG, the sum of the diameters of all single conductor cables shall not exceed the cable tray width. Table 392.22(B)(1) Allowable Cable Fill Area for Single-Conductor Cables in Ladder, Ventilated Trough, or Wire Mesh Cable Trays for Cables Rated 2000 Volts or Less Inside Width of Cable Tray Maximum Allowable Fill Area for Single-Conductor Cables in Ladder, Ventilated Trough, or Wire Mesh Cable Trays Column 1 Applicable for 392.22(B)(1)(b) Only Column 2a Applicable for 392.22(B)(1)(c) Only mm in. mm2 in.2 mm2 in.2 50 2 1,400 2.0 1,400 – (28 Sd)b 2.0 – (1.1 Sd)b 100 4 2,800 4.5 2,800 – (28 Sd) 4.5 – (1.1 Sd) 150 6 4,200 6.5 4,200 – (28 Sd)b 6.5 – (1.1 Sd)b 200 8 5,600 8.5 5,600 – (28 Sd) 8.5 – (1.1 Sd) 225 9 6,100 9.5 6,100 – (28 Sd) 9.5 – (1.1 Sd) 300 12 8,400 13.0 8,400 – (28 Sd) 13.0 – (1.1 Sd) 400 16 11,200 17.5 11,200 – (28 Sd) 17.5 – (1.1 Sd) 450 18 12,600 19.5 12,600 – (28 Sd) 19.5 – (1.1 Sd) 500 20 14,000 21.5 14,000 – (28 Sd) 21.5 – (1.1 Sd) 600 24 16,800 26.0 16,800 – (28 Sd) 26.0 – (1.1 Sd) 750 30 21,000 32.5 21,000 – (28 Sd) 32.5 – (1.1 Sd) 900 36 25,200 39.0 25,200 – (28 Sd) 39.0 – (1.1 Sd) aThe maximum allowable fill areas in Column 2 shall be calculated. For example, the maximum allowable fill, in mm2, for a 150-mm wide cable tray in Column 2 shall be 4200 minus (28 multiplied by Sd) [the maximum allowable fill, in square inches, for a 6-in. wide cable tray in Column 2 shall be 6.5 minus (1.1 multiplied by Sd)]. bThe term Sd in Column 2 is equal to the sum of the diameters, in mm, of all cables 507 mm2 (in inches, of all 1000 kcmil) and larger single-conductor cables in the same cable tray with small cables. Ventilated Channel Cable Trays. Where 50 mm (2 in.), 75 mm (3 in.), 100 mm (4 in.), or 150 mm (6 in.) wide ventilated channel cable trays contain single-conductor cables, the sum of the diameters of all single conductors shall not exceed the inside width of the channel. Number of Type MV and Type MC Cables (2001 Volts or Over) in Cable Trays. The number of cables rated 2001 volts or over permitted in a single cable tray shall not exceed the requirements of this section. The sum of the diameters of single-conductor and multiconductor cables shall not exceed the cable tray width, and the cables shall be installed in a single layer. Where single conductor cables are triplexed, quadruplexed, or bound together in circuit groups, the sum of the diameters of the single conductors shall not exceed the cable tray width, and these groups shall be installed in single layer arrangement. 392.30 Securing and Supporting. (A) Cable Trays. Cable trays shall be supported at intervals in accordance with the installation instructions. Cables and Conductors. Cables and conductors shall be secured to and supported by the cable tray system in accordance with the following, as applicable: In other than horizontal runs, the cables shall be fastened securely to transverse members of the cable tray. Supports shall be provided to prevent stress on cables where they enter raceways from cable tray systems. The system shall provide for the support of cables and raceway wiring methods in accordance with their corresponding articles. Where cable trays support individual conductors or multiconductor cables and where the conductors or multiconductor cables pass from one cable tray to another, or from a cable tray to raceway(s) or from a cable tray to equipment where the conductors are terminated, the distance between the cable trays or between the cable tray and the raceway(s) or the equipment shall not exceed 1.8 m (6 ft). The conductors shall be secured to the cable tray(s) at the transition, and they shall be protected, by guarding or by location, from physical damage. Cable ties shall be listed and identified for the application and for securement and support. ENHANCED CONTENT Collapse The 6-foot distance limit specified in 392.30(B)(3) applies to mechanically discontinuous cable tray segments for individual conductors including trays containing multiconductor cables. Cables installed within cable tray systems must meet the support requirements of the applicable NEC article that covers the cables. This requirement either limits the gap distance in cable tray runs and between the cable tray and the equipment enclosures or requires intermediate cable supports at the appropriate distances in place of the cable tray. See 336.10(7) regarding multiconductor Type TC tray cable used with discontinuous cable tray. 392.44 Expansion Splice Plates. Expansion splice plates for cable trays shall be provided where necessary to compensate for thermal expansion and contraction. 392.46 Bushed Conduit and Tubing. A box shall not be required where cables or conductors are installed in bushed conduit and tubing used for support or for protection against physical damage or where conductors or cables transition to a raceway wiring method from the cable tray. Conductors shall be permitted to enter equipment in accordance with 392.46(A) or (B). Through Bushed Conduit or Tubing. Individual conductors or multiconductor cables with entirely nonmetallic sheaths shall be permitted to enter enclosures where they are terminated through nonflexible bushed conduit or tubing installed for their protection provided they are secured at the point of transition from the cable tray and the conduit or tubing is sealed at the outer end using an approved means so as to prevent debris from entering the equipment through the conduit or tubing. Flanged Connections. Individual conductors or multiconductor cables with entirely nonmetallic sheaths shall be permitted to enter enclosures through openings associated with flanges from cable trays where the cable tray is attached to the flange and the flange is mounted directly to the equipment. The openings shall be made such that the conductors are protected from abrasion and the opening shall be sealed or covered to prevent debris from entering the enclosure through the opening. Informational Note: One method of preventing debris from entering the enclosure is to seal the outer end of the raceway or the opening with duct seal. 392.56 Cable Splices and Type MV Cable Joints. Cable splices and Type MV cable joints made and insulated by approved methods shall be permitted to be located within a cable tray, provided they are accessible. Splices and Type MV cable joints shall be permitted to project above the side rails where not subject to physical damage. 392.60 Grounding and Bonding. (A) Metal Cable Trays. Metal cable trays shall be permitted to be used as equipment grounding conductors where continuous maintenance and supervision ensure that qualified persons service the installed cable tray system and the cable tray complies with this section. Metal cable trays that support electrical conductors shall be grounded as required for conductor enclosures in accordance with 250.96 and Part IV of Article 250. Metal cable trays containing only non-power conductors shall be electrically continuous through approved connections or the use of a bonding jumper. Informational Note: Examples of non-power conductors include nonconductive optical fiber cables and Class 2 and Class 3 remote-control, signaling, and power-limited circuits. ENHANCED CONTENT Collapse Section 392.60(A), together with 250.96, requires all cable tray systems that support electrical conductors (whether mechanically continuous or with isolated segments) to be electrically continuous and effectively bonded and grounded. This requirement applies whether the cable tray is used as an equipment grounding conductor (EGC) or is used for service conductors and connected to the grounded system conductor (or the grounding electrode conductor for ungrounded systems). Where a metal cable tray contains only non-power conductors, such as fire alarm, communications, community antenna television (CATV), or broadband conductors, the tray must be maintained electrically continuous. Steel or Aluminum Cable Tray Systems. Steel or aluminum cable tray systems shall be permitted to be used as equipment grounding conductors, provided all the following requirements are met: The cable tray sections and fittings are identified as an equipment grounding conductor. The minimum cross-sectional area of cable trays conform to the requirements in Table 392.60(B). All cable tray sections and fittings are legibly and durably marked to show the cross-sectional area of metal in channel cable trays, or cable trays of one-piece construction, and the total cross-sectional area of both side rails for ladder or trough cable trays. Cable tray sections, fittings, and connected raceways are bonded in accordance with 250.96, using bolted mechanical connectors or bonding jumpers sized and installed in accordance with 250.102. Table 392.60(B) Metal Area Requirements for Cable Trays Used as Equipment Grounding Conductor Maximum Fuse Ampere Rating, Circuit Breaker Ampere Trip Setting, or Circuit Breaker Protective Relay Ampere Trip Setting for Ground-Fault Protection of Any Cable Circuit in the Cable Tray System Minimum Cross-Sectional Area of Metal Steel Cable Trays Aluminum Cable Trays mm2 in.2 mm2 in.2 60 129 0.20 129 0.20 100 258 0.40 129 0.20 200 451.5 0.70 129 0.20 400 645 1.00 258 0.40 600 967.5 1.50† 258 0.40 1000 — — 387 0.60 1200 — — 645 1.00 1600 — — 967.5 1.50 2000 — — 1290 2.00† Total cross-sectional area of both side rails for ladder or trough cable trays; or the minimum cross-sectional area of metal in channel cable trays or cable trays of one-piece construction. †Steel cable trays shall not be used as equipment grounding conductors for circuits with ground-fault protection above 600 amperes. Aluminum cable trays shall not be used as equipment grounding conductors for circuits with ground-fault protection above 2000 amperes. ENHANCED CONTENT Collapse Designers of cable tray systems, for use in establishments that qualify, can specify cables without EGCs and use the cable tray system as the required EGC, provided the cable tray system meets the requirements of 392.60(A) and (B). An example of the grounding and bonding of multiconductor cables in cable trays with conduit runs to power equipment is illustrated below. Bonding jumpers connecting discontinuous sections of cable tray used as an EGC are on the load side of the overcurrent device. The equipment bonding jumper must be sized in accordance with 250.102(D). Transitions. Where metal cable tray systems are mechanically discontinuous, as permitted in 392.18(A), a bonding jumper sized in accordance with 250.102 shall connect the two sections of the cable tray, or the cable tray and the raceway or equipment. Bonding shall be in accordance with 250.96. ENHANCED CONTENT Collapse The bonding of the entire cable tray system is important, especially for discontinuous cable tray segments. According to 250.96(A), properly sized and installed bonding conductors must be installed across any mechanical discontinuities in the cable tray system and across any space between the cable tray and the conductor termination equipment enclosure or its equipment ground bus. 392.80 Ampacity of Conductors. (A) Ampacity of Cables, Rated 2000 Volts or Less, in Cable Trays. Informational Note: See 110.14(C) for conductor temperature limitations due to termination provisions. (1) Multiconductor Cables. The ampacity of multiconductor cables, nominally rated 2000 volts or less, installed according to the requirements of 392.22(A) shall be as given in Table 310.16 and Table 310.18, subject to 392.80(A)(1)(a), (A)(1)(b), (A)⁠(1)(c), and 310.14(A)(2). (a) The adjustment factors of 310.15(C)(1) shall apply only to multiconductor cables with more than three current-carrying conductors. Adjustment factors shall be limited to the number of current-carrying conductors in the cable and not to the number of conductors in the cable tray. Where cable trays are continuously covered for more than 1.8 m (6 ft) with solid unventilated covers, not over 95 percent of the ampacities of Table 310.16 and Table 310.18 shall be permitted for multiconductor cables. Where multiconductor cables are installed in a single layer in uncovered trays, with a maintained spacing of not less than one cable diameter between cables, the ampacity shall not exceed the ambient temperature-corrected ampacities of multiconductor cables, with not more than three insulated conductors rated 0 through 2000 volts in free air, in accordance with 310.14(B). Informational Note: See Informative Annex B, Table B.‍2(3). ENHANCED CONTENT Collapse The cables shown in the exhibit below, rated 2000 volts or less, are installed in a single layer in an uncovered tray, with not less than one cable diameter between cables and not more than three conductors per cable. See Table B.2(3) in Informative Annex B for the ampacity of the conductors in this configuration. Single-Conductor Cables. The ampacity of single-conductor cables shall be as permitted by 310.14(A)(2). The adjustment factors of 310.15(C)(1) shall not apply to the ampacity of cables in cable trays. The ampacity of single-conductor cables, or single conductors cabled together (triplexed, quadruplexed, and so forth), nominally rated 2000 volts or less, shall comply with 392.80(A)(2)(a) through (A)(2)(d). Where installed according to the requirements of 392.22(B), the ampacities for 600 kcmil and larger single-conductor cables in uncovered cable trays shall not exceed 75 percent of the ampacities in Table 310.17 and Table 310.19. Where cable trays are continuously covered for more than 1.8 m (6 ft) with solid unventilated covers, the ampacities for 600 kcmil and larger cables shall not exceed 70 percent of the ampacities in Table 310.17 and Table 310.19. Where installed according to the requirements of 392.22(B), the ampacities for 1/0 AWG through 500 kcmil single-conductor cables in uncovered cable trays shall not exceed 65 percent of the ampacities in Table 310.17 and Table 310.19. Where cable trays are continuously covered for more than 1.8 m (6 ft) with solid unventilated covers, the ampacities for 1/0 AWG through 500 kcmil cables shall not exceed 60 percent of the ampacities in Table 310.17 and Table 310.19. Where single conductors are installed in a single layer in uncovered cable trays, with a maintained space of not less than one cable diameter between individual conductors, the ampacity of 1/0 AWG and larger cables shall not exceed the ampacities in Table 310.17 and Table 310.19. Exception to (c): For solid bottom cable trays, the ampacity of single conductor cables shall be determined by 310.14(B). Where single conductors are installed in a triangular or square configuration in uncovered cable trays, with a maintained free airspace of not less than 2.15 times one conductor diameter (2.15 × O.D.) of the largest conductor contained within the configuration and adjacent conductor configurations or cables, the ampacity of 1/0 AWG and larger cables shall not exceed the ampacities of two or three single insulated conductors rated 0 through 2000 volts supported on a messenger in accordance with 310.15. Informational Note: See Table 310.20. ENHANCED CONTENT Collapse The configuration of the conductors in the cable tray is the basis for determining the cable’s ampacity. The installation must be consistent with the specifications used in the design of the cable tray system. Section 392.80(A)(2)(d) recognizes single conductors in a triangular configuration installed in a cable tray with maintained spacing as having the same ampacity as three single insulated conductors on a messenger. The maintained spacing allows air to circulate around the cable. Where three single conductors, nominally rated 2000 volts or less, are cabled together in a triangular configuration, with not less than 2.15 times the conductor diameter (2.15 × OD) between groups, as illustrated below, the ampacity of the conductors is determined in accordance with Table 310.20. Where single conductors are installed in cable trays, their ampacities are permitted to be calculated using the applicable table. Where single-conductor cables emerge from a cable tray installation and are terminated at circuit breakers, distribution switchgear, and similar electrical equipment, the temperature limitations of the electrical equipment terminals should be coordinated with the ampacity of the single-conductor cables. As stated in both the UL Guide Information for Electrical Equipment Directory and in 110.14(C)(1), unless the equipment is listed and marked otherwise, conductor ampacities used in determining equipment terminations must be based on Table 310.16 as modified by 310.15(B) and (C). Combinations of Multiconductor and Single-Conductor Cables. Where a cable tray contains a combination of multiconductor and single-conductor cables, the ampacities shall be as given in 392.80(A)(1) for multiconductor cables and 392.80(A)(2) for single-conductor cables, provided that the following conditions apply: The sum of the multiconductor cable fill area as a percentage of the allowable fill area for the tray calculated in accordance with 392.22(A), and the single-conductor cable fill area as a percentage of the allowable fill area for the tray calculated in accordance with 392.22(B), totals not more than 100 percent. Multiconductor cables are installed according to 392.22(A), and single-conductor cables are installed according to 392.22(B) and 392.22(C). Ampacity of Type MV and Type MC Cables (2001 Volts or Over) in Cable Trays. The ampacity of cables, rated 2001 volts, nominal, or over, installed according to 392.22(C) shall not exceed the requirements of this section. Informational Note: See 110.40 for conductor temperature limitations due to termination provisions. (1) Multiconductor Cables (2001 Volts or Over). The ampacity of multiconductor cables shall be as given in Table 315.60(C)(9) and Table 315.60(C)(10), subject to the following: Where cable trays are continuously covered for more than 1.8 m (6 ft) with solid unventilated covers, not more than 95 percent of the ampacities of Table 315.60(C)(9) and Table 315.60(C)(10) shall be permitted for multiconductor cables. Where multiconductor cables are installed in a single layer in uncovered cable trays, with maintained spacing of not less than one cable diameter between cables, the ampacity shall not exceed the allowable ampacities of Table 315.60(C)(5) and Table 315.60(C)(6). Single-Conductor Cables (2001 Volts or Over). The ampacity of single-conductor cables, or single conductors cabled together (triplexed, quadruplexed, and so forth), shall comply with the following: The ampacities for 1/0 AWG and larger single-conductor cables in uncovered cable trays shall not exceed 75 percent of the ampacities in Table 315.60(C)(3) and Table 315.60(C)(4). Where the cable trays are covered for more than 1.8 m (6 ft) with solid unventilated covers, the ampacities for 1/0 AWG and larger single-conductor cables shall not exceed 70 percent of the ampacities in Table 315.60(C)(3) and Table 315.60(C)(4). Where single-conductor cables are installed in a single layer in uncovered cable trays, with a maintained space of not less than one cable diameter between individual conductors, the ampacity of 1/0 AWG and larger cables shall not exceed the ampacities in Table 315.60(C)(3) and Table 315.60(C)(4). Where single conductors are installed in a triangular or square configuration in uncovered cable trays, with a maintained free air space of not less than 2.15 times the diameter (2.15 × O.D.) of the largest conductor contained within the configuration and adjacent conductor configurations or cables, the ampacity of 1/0 AWG and larger cables shall not exceed the ampacities in Table 315.60(C)(1) and Table 315.60(C)(2). Part III. Construction Specifications 392.100 Construction. (A) Strength and Rigidity. Cable trays shall have suitable strength and rigidity to provide adequate support for all contained wiring. Smooth Edges. Cable trays shall not have sharp edges, burrs, or projections that could damage the insulation or jackets of the wiring. Corrosion Protection. Cable tray systems shall be corrosion resistant. If made of ferrous material, the system shall be protected from corrosion as required by 300.6. Side Rails. Cable trays shall have side rails or equivalent structural members. Fittings. Cable trays shall include fittings or other suitable means for changes in direction and elevation of runs. Nonmetallic Cable Tray. Nonmetallic cable trays shall be made of flame-retardant material.