Derating Cables in a cable Tray

[fmg78360]

When derating Olflex VFD slim cables with three black conductors plus a green ground, going through a fully enclosed cable tray, how do you derate these cables?

Do you count 4 current carrying conductors or 3?

Do you use the derating factor for the three current carrying conductors and ambient temp or do you count all the conductors in each cable and then use the derating factor for all of them and the ambient temperature factor?

 

[RUWired]

When derating Olflex VFD slim cables with three black conductors plus a green ground, going through a fully enclosed cable tray, how do you derate these cables?

Do you count 4 current carrying conductors or 3?

Do you use the derating factor for the three current carrying conductors and ambient temp or do you count all the conductors in each cable and then use the derating factor for all of them and the ambient temperature factor?

I think article 392.11 will answer your questions.You don't count the ground as a current carrying conductors.

392.11 Ampacity of Cables, Rated 2000 Volts or Less, in Cable Trays
(1) The derating factors of 310.15(B)(2)(a) shall apply only to multiconductor cables with more than three current-carrying conductors. Derating shall be limited to the number of current-carrying conductors in the cable and not to the number of conductors in the cable tray.
(2) Where cable trays are continuously covered for more than 1.8 m (6 ft) with solid unventilated covers, not over 95 percent of the allowable ampacities of Tables 310.16 and 310.18 shall be permitted for multiconductor cables.

 

[weressl]

When derating Olflex VFD slim cables with three black conductors plus a green ground, going through a fully enclosed cable tray, how do you derate these cables?

Do you count 4 current carrying conductors or 3?

Do you use the derating factor for the three current carrying conductors and ambient temp or do you count all the conductors in each cable and then use the derating factor for all of them and the ambient temperature factor?

3...........