400 vs. 350 Amps Circuit Breaker
400 vs. 350 Amps Circuit Breaker
(OP)
We do have a 200Hp/460V/3ph/60Hz motor. The NEC tells me that the size of the circuit breaker (CB) should be 350 Amps. If we use a 400 Amps CB, is it violation of the NEC?
FLA of this motor is 240 Amps.
Thank you indeed in advance!
FLA of this motor is 240 Amps.
Thank you indeed in advance!





RE: 400 vs. 350 Amps Circuit Breaker
NEC would allow up to 250% of the FLA rated CB. Look up Table 430.52 in NEC 430.
RE: 400 vs. 350 Amps Circuit Breaker
I see it now at that 2005 NEC table 430.52 last column.
The motor is not on the VFD but there is an auto transformer starter. I was not sure what it is the maximum rating for these CB’s,... Thanks again!
RE: 400 vs. 350 Amps Circuit Breaker
RE: 400 vs. 350 Amps Circuit Breaker
It is helpful information.