Cable tray fill calculation 2

[lakesailer]

Being new to applications utilizing cable tray, could someone tell me if it's acceptable to install multi-conductor 600V tray cable and single conductor 600V tray rated cable in the same cable tray?

If so, NEC doesn't appear to have any reference to calculating the allowable fill area for the tray when the two wiring types are mixed.

 

[mcgyvr]

See NEC (2005) 392.9 (A)

 

[EEJaime]

As long as you do not exceed the capacity of the cable tray. Any quantity and configuration of conductors is acceptable as long as they have the same insulation voltage rating, in your case 600V. So you may combine the two. The NEC section referenced by MCGYVR will let you calculate the fill area.

 

[lakesailer]

In our application we are running 3 parallel runs of (phase A,B,C, and Gnd) for the power to a 700hp VFD. Am I correct that if we space the groups of 4 cables each, apart from each other by the 2.15 times the cable O.D., that we can use NEC table 310.20 to determine the ampacity for the phase conductors? When the groups of 4 cables each leave the cable tray, each group will route through an individual 18 inch long conduit/nipple into the top of the VFD cabinet.

 

[nickoliver]

You didn't specify weather you are using multi conductor tray cable or single conductor cables grouped. If single conductor, yes. If its tray cable you size per B.310.3 in Annex B.