2013
Channel Size and Fill
Capacity
Channel Size and Fill Capacity Snap Track channel tray is manufactured in nominal widths of 2”, 4”, and 6” and a nominal depth of 2”. The appropriate size and number of channels depends on the number and size of the conductors required, and the allowable fill area specified in the guidance provided by NEC. Consideration should also be given to EMI effects. Because the Snap Track system uniquely offers flexibility for expansion and changes, engineers and designers should design and size, systems to anticipate both current and future needs. Permitted Fill Capacity per NEC NEC Section 392.22 Number of Conductors or Cables (A) The number of multi‐conductor cables, rated 2000 volts or less, permitted in a single cable tray shall not exceed the requirements of this section. The conductor sizes apply to both aluminum and copper conductors. 392.22 (5) Ventilated Channel Containing Multiple conductors Cables of ANY type. Where ventilated channel trays contain multi‐conductor cables of any type, the following shall apply: (a) Where only one multi‐conductor cable is installed, the cross sectional area shall not exceed the value specified in Column 1 of table 392.22 (5). (b) Where more than one multi‐conductor 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 Multi‐conductor Cables in Ventilated Channel Cable Trays for Cables Rated 2000 Volts or Less. Maximum Allowable Fill Area for Multi‐conductor Cables Inside Width of Cable Tray mm 75 100 150 in. 3 4 6 Column 1
One Cable mm 2 1500
2900
4500
in. 2 2.3
4.5
7.0
Column 2
More Than One Cable mm 2 in 2 850
1.3 1600 2.5 2450 3.8 P 1 Techline Mfg. recommends the guidelines set forth in NEC Table 392.22 (A) (5), for Multi‐
conductor cables when considering the fill capacity of Snap Track 4” and 6” width channels. However, note that the NEC Table 392.22 (A) (5) does not provide guidance for Multi‐conductor cables in two inch 2” width trays. Therefore, Techline mfg. recommends and refers to the NEC Table 392.22 (A) (6) for Snap Track 2” tray. Although NEC Table 392.22 (A) (6) clearly is intended for solid bottom tray it is the only guidance provided for Multi‐conductor cable when installed in 2” channel. Further the capacities listed in the NEC Table 392.22 (A) (6) are more conservative than those listed in NEC Table 392.22 (A) (5) for ventilated bottom channel tray. Table 392.22 (A) (6) Allowable Cable Fill Area for Multi‐conductor Cables in Solid Channel Cable Trays for Cables Rated 2000 Volts or Less. Maximum Allowable Fill Area for Multi‐conductor Cables Inside Width of Cable Tray mm 50 75 100 150 in. 2 3 4 6 Column 1
One Cable mm 2 850
1500
2900
4500
in. 2 1.3
2.0
3.7
5.5
Column 2
More Than One Cable mm 2 In 2 500
0.8 850
1.1 1600 2.1 2450 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 apply to both aluminum and copper conductors. (B) (2) Ventilated Channel Trays. Where 50 mm (2 in.), 75 mm (3”), 100 mm (4”), or 150mm (6”) 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. Techline Mfg. recommends following the guidelines set forth under NEC section 392.22 (B) when installing single‐conductor cables in Snap Track Tray. P 2