bjenks
Electrical
- Jul 14, 2006
- 68
I am getting mixed feedback from different sources on how to size the overcurrent protection device for a generator feeding an ATS that is dedicated to the fire pump. When I read 695.4(B) it says overcurrent protective devices between an on-site standby generator and a fire pump controller shall be selected and sized according to 430.62 to provide short-circuit protection only. 430.62(A) Exception No.1 says where one or more instantaneous trip circuit breakers are used the max is based on table 430.52. So when I sized the breaker I used a Magnetic CB that was sized at 250% of the FLA. About half the people I talk to say to size it the same as the primary source protection at RLA. NFPA 20-A.9.6.5 leads me to believe I am doing this right. Any other opinions? Please back up with code.