powersystems
Member
I have a couple of issues but they pertain to the same problem.
I have a feeder coming from a 400 amp main switch we ran (2) 2" w/ 3/0 thhn my two questions are
1)For derating for the # of conductors do I need to use 4 (80%)or do I need to count all of the conductors as if they were in 1 conduit and use 8 conductors (70%).
2) If I use 80%(which I think is correct) of 3/0 in the 90 degree column (225*2*.80) I get 360 amps and go to the next standard size CB I should be able to install these wires to a 400 amp CB does this sound accurate or am I missing something??
Thank you for any input
Kevin
I have a feeder coming from a 400 amp main switch we ran (2) 2" w/ 3/0 thhn my two questions are
1)For derating for the # of conductors do I need to use 4 (80%)or do I need to count all of the conductors as if they were in 1 conduit and use 8 conductors (70%).
2) If I use 80%(which I think is correct) of 3/0 in the 90 degree column (225*2*.80) I get 360 amps and go to the next standard size CB I should be able to install these wires to a 400 amp CB does this sound accurate or am I missing something??
Thank you for any input
Kevin