roof feeder

[Toros]

Hi,
per my calculation ,
Considering that the total load on the roof mounted panel which is 105A,
using temp. djastm/derating , 142 Deg ., 65% of ampacity of 3/0 cu wire which is 145 amp.

inspector told us to use 150A breaker in the 3ph service to protect that panel through the 3/0 conductors
NOT 200A breaker.

is he right????

 

[augie47]

If your adjusted ampacity for the 3/0 is 145 amps, he is correct. Conductors must be protected at their (adjusted) ampacity and "next size up rule"

 

[infinity]

Use XHHW-2 and forget the derating.

 

[augie47]

Use XHHW-2 and forget the derating.

kudos.. why can I never remember that :ashamed1: