Derating

[mstrlucky74]

So I have apt. dist panel feeding apt. panels Groups of three apt. panels are sharing the same raceway….O’s, P’s Q’s etc. So I have a 2” with 6 #1’s and 1#1 neutral( they all share a neutral) for the three panels. Each panel fed by a 100A breaker and each apt. panel is 100A. They are single phase panels. So I’ running a 2” to the first panel with 7#1’s then dropping of 2#1’s then 5 #1’s to the second panel then 3 #1’s to the last.

Don’t I have to derate the #1’s due to conductor bundling.? Not sure by how much as the run starts with 7 conductors( so that would be 70% current carrying capacity) but then drops off.

 

[infinity]

The section of raceway with the 7 conductors and the section with 5 conductors both require derating. #1 AWG = 145 amps*70% = 101.5 amps.

 

[david luchini]

Don’t I have to derate the #1’s due to conductor bundling.? Not sure by how much as the run starts with 7 conductors( so that would be 70% current carrying capacity) but then drops off.

70% is correct, as Rob noted. #2awg 90Deg conductors would be the smallest allowable conductor size.