Rated 2000 Volts or Less
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Inside Width of Cable Tray |
Maximum Allowable Fill Area for Multiconductor Cables |
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Inside Width of Cable Tray |
Ladder or Ventilated Trough Cable Trays, 392.9(A) |
Solid Bottom Cable Trays, 392.9(C) |
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Inside Width of Cable Tray |
Column 1 Applicable for 392.9(A)(2) Only |
Column 2" Applicable for 392.9(A)(3) Only |
Column 3 Applicable for 392.9(C)(2) Only |
Column 4" Applicable for 392.9(C)(3) Only |
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mm in. |
mm2 in.2 |
mm2 in.2 |
mm2 in.2 |
mm2 in.2 |
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150 6.0 225 9.0 300 12.0 450 18.0 600 24.0 750 30.0 900 36.0 |
4,500 7.0 6,800 10.5 9,000 14.0 13,500 21.0 18,000 28.0 22,500 35.0 27,000 42.0 |
4,500 - (30 Sd) b 7-(1.2Sd)b 6,800- (30 Sd) 10.5-(1.2 Sd) 9,000-(30 Sd) 14-(1.2Sd) 13,500-(30 Sd) 21- (1.2 Sd) 18,000-(30 Sd) 28- (1.2Sd) 22,500 - (30 Sd) 35- (1.2Sd) 27,000 - (30 Sd) 42- (1.2Sd) |
3,500 5.5 5,100 8.0 7,100 11.0 10,600 16.5 14,200 22.0 17,700 27.5 21,300 33.0 |
3,500-(25 Sd b) 5.5-Sd b 5,10O-(25 Sd) 8.0-Sd 7,100-(25 Sd) 11.0-Sd 10,600-(25 Sd) 16.5-Sd 14,200-(25 Sd) 22.0-Sd 17,700-(25 Sd) 27.5-Sd 21,30O-(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 mm 2 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)].
'The 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.
(D) Solid Bottom Cable Tray — Multiconductor Con trol 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.).
(E) Ventilated Channel Cable Trays. Where ventilated channel cable trays contain multiconductor cables of any type, the following shall apply:
(1) Where only one multiconductor cable is installed, the cross-sectional area shall not exceed the value specified in Column 1 of Table 392.9(E).
(2) 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 392.9(E).
(F) Solid Channel Cable Trays. Where solid channel cable trays contain multiconductor cables of any type, the following shall apply:
(1) 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
392.9(F).
(2) Where more than one multiconductor