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The number of multiconductor cables, rated 2000 volts or less, permitted in a single cable tray shall not exceed the requirements of this section. The conductor sizes shall apply to both aluminum and copper conductors. Where dividers are used, fill calculations shall apply to each divided section of the cable tray.
Table 392.22(A) Allowable Cable Fill Area for Multiconductor Cables in Ladder, Ventilated Trough, or Solid Bottom Cable Trays for Cables Rated 2000 Volts or Less
Inside Width of Cable Tray Maximum Allowable Fill Area for Multiconductor Cables
Ladder or Ventilated Trough or Wire Mesh Cable Trays, 392.22(A)(1) Solid Bottom Cable Trays, 392.22(A)(3)
Column 1 Applicable for 392.22(A)(1)(b) Only Column 2a Applicable for 392.22(A)(1)(c) Only Column 3 Applicable for 392.22(A)(3)(b) Only Column 4a Applicable for 392.22(A)(3)(c) Only
mm in. mm2 in.2 mm2 in.2 mm2 in.2 mm2 in.2
50 2.0 1,500 2.5 1,500 — (30 Sd)b 2.5 — (1.2 Sd)b 1,200 2.0 1,200 — (25 Sd)b 2.0 — Sdb
100 4.0 3,000 4.5 3,000 — (30 Sd)b 4.5 — (1.2 Sd) 2,300 3.5 2,300 — (25 Sd) 3.5 — Sd
150 6.0 4,500 7.0 4,500 — (30 Sd)b 7 — (1.2 Sd) 3,500 5.5 3,500 — (25 Sd)b 5.5—Sd
200 8.0 6,000 9.5 6,000 — (30 Sd)b 9.5 — (1.2 Sd) 4,500 7.0 4,500 — (25 Sd) 7.0 — Sd
225 9.0 6,800 10.5 6,800 — (30 Sd) 10.5 — (1.2 Sd) 5,100 8.0 5,100 — (25 Sd) 8.0 — Sd
300 12.0 9,000 14.0 9,000 — (30 Sd) 14 — (1.2 Sd) 7,100 11.0 7,100 — (25 Sd) 11.0 — Sd
400 16.0 12,000 18.5 12,000 — (30 Sd) 18.5 — (1.2 Sd) 9,400 14.5 9,400 — (25 Sd) 14.5 — Sd
450 18.0 13,500 21.0 13,500 — (30 Sd) 21 — (1.2 Sd) 10,600 16.5 10,600 — (25 Sd) 16.5 — Sd
500 20.0 15,000 23.5 15,000 — (30 Sd) 23.5 — (1.2 Sd) 11,800 18.5 11,800 — (25 Sd) 18.5 — Sd
600 24.0 18,000 28.0 18,000 — (30 Sd) 28 — (1.2 Sd) 14,200 22.0 14,200 — (25 Sd) 22.0 — Sd
750 30.0 22,500 35.0 22,500 — (30 Sd) 35 — (1.2 Sd) 17,700 27.5 17,700 — (25 Sd) 27.5 — Sd
900 36.0 27,000 42.0 27,000 — (30 Sd) 42 — (1.2 Sd) 21,300 33.0 21,300 — (25 Sd) 33.0 — Sd
aThe maximum allowable fill areas in Columns 2 and 4 shall be calculated. For example, the maximum allowable fill in mm2 for a 150-mm wide cable tray in Column 2 shall be 4500 minus (30 multiplied by Sd) [the maximum allowable fill, in square inches, for a 6-in. wide cable tray in Column 2 shall be 7 minus (1.2 multiplied by Sd)].
bThe term Sd in Columns 2 and 4 is equal to the sum of the diameters, in mm, of all cables 107.2 mm (in inches, of all 4/0 AWG) and larger multiconductor cables in the same cable tray with smaller cables.
(1) Ladder or Ventilated Trough Cable Trays Containing Any Mixture of Cables
Where ladder or ventilated trough cable trays contain multiconductor power or lighting cables, or any mixture of multiconductor power, lighting, control, and signal cables, the maximum number of cables shall conform to the following:
(a) Where all of the cables are 4/0 AWG or larger, the sum of the diameters of all cables shall not exceed the cable tray width, and the cables shall be installed in a single layer. Where the cable ampacity is determined according to 392.80(A)(1)(c), the cable tray width shall not be less than the sum of the diameters of the cables and the sum of the required spacing widths between the cables.
(b) Where all of the cables are smaller than 4/0 AWG, the sum of the cross-sectional areas of all cables shall not exceed the maximum allowable cable fill area in Column 1 of Table 392.22(A) for the appropriate cable tray width.
(c) Where 4/0 AWG or larger cables are installed in the same cable tray with cables smaller than 4/0 AWG, the sum of the cross-sectional areas of all cables smaller than 4/0 AWG shall not exceed the maximum allowable fill area resulting from the calculation in Column 2 of Table 392.22(A) for the appropriate cable tray width. The 4/0 AWG and larger cables shall be installed in a single layer, and no other cables shall be placed on them.
(2) Ladder or Ventilated Trough Cable Trays Containing Multiconductor Control and/or Signal Cables Only
Where a ladder or ventilated trough cable tray having a usable inside depth of 150 mm (6 in.) or less contains multiconductor control and/or signal cables only, the sum of the cross-sectional areas of all cables at any cross section shall not exceed 50 percent of the interior cross-sectional area of the cable tray. A depth of 150 mm (6 in.) shall be used to calculate the allowable interior cross-sectional area of any cable tray that has a usable inside depth of more than 150 mm (6 in.).
(3) Solid Bottom Cable Trays Containing Any Mixture of Cables
Where solid bottom cable trays contain multiconductor power or lighting cables, or any mixture of multiconductor power, lighting, control, and signal cables, the maximum number of cables shall conform to the following:
(a) Where all of the cables are 4/0 AWG or larger, the sum of the diameters of all cables shall not exceed 90 percent of the cable tray width, and the cables shall be installed in a single layer.
(b) Where all of the cables are smaller than 4/0 AWG, the sum of the cross-sectional areas of all cables shall not exceed the maximum allowable cable fill area in Column 3 of Table 392.22(A) for the appropriate cable tray width.
(c) Where 4/0 AWG or larger cables are installed in the same cable tray with cables smaller than 4/0 AWG, the sum of the cross-sectional areas of all cables smaller than 4/0 AWG shall not exceed the maximum allowable fill area resulting from the computation in Column 4 of Table 392.22(A) for the appropriate cable tray width. The 4/0 AWG and larger cables shall be installed in a single layer, and no other cables shall be placed on them.
(4) Solid Bottom Cable Tray Containing Multiconductor Control and/or Signal Cables Only
Where a solid bottom cable tray having a usable inside depth of 150 mm (6 in.) or less contains multiconductor control and/or signal cables only, the sum of the cross sectional areas of all cables at any cross section shall not exceed 40 percent of the interior cross-sectional area of the cable tray. A depth of 150 mm (6 in.) shall be used to calculate the allowable interior cross-sectional area of any cable tray that has a usable inside depth of more than 150 mm (6 in.).
(5) Ventilated Channel Cable Trays Containing Multiconductor Cables of Any Type
Where ventilated channel cable trays contain multiconductor cables of any type, the following shall apply:
(a) Where only one multiconductor cable is installed, the cross-sectional area shall not exceed the value specified in Column 1 of Table 392.22(A)(5).
(b) Where more than one multiconductor cable is installed, the sum of the cross-sectional area of all cables shall not exceed the value specified in Column 2 of Table 392.22(A)(5).
Table 392.22(A)(5) Allowable Cable Fill Area for Multiconductor Cables in Ventilated Channel Cable Trays for Cables Rated 2000 Volts or Less
Inside Width of Cable Tray Maximum Allowable Fill Area for Multiconductor Cables
Column 1 One Cable Column 2 More Than One Cable
mm in. mm2 in.2 mm2 in.2
75 3 1500 2.3 850 1.3
100 4 2900 4.5 1600 2.5
150 6 4500 7.0 2450 3.8
(6) Solid Channel Cable Trays Containing Multiconductor Cables of Any Type
Where solid channel cable trays contain multiconductor cables of any type, the following shall apply:
(a) Where only one multiconductor cable is installed, the cross-sectional area of the cable shall not exceed the value specified in Column 1 of Table 392.22(A)(6).
(b) 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

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