Fire Pump Utility feed

[Shujinko]

I have a fire pump question. On the normal side of a fire pump controller with an integral ATS I have a service entrance rated enclosed circuit breaker (ECB) fed from the utility. I sized the ECB based on the NEC 695.4(2)(a) taking into consideration the locked rotor amps. But NEC 695.6(C) prohibits overload protection which is why I am specifying a magnetic trip only ECB. Why would we be required to size the ECB to carry the LRA indefinitely if a magnetic trip only breaker would trip at alot higher than the LRA. If would trip only on a very high fault. So what's the point on sizing based on the LRA if the available fault current that the service transformer can supply is alot higher than the LRA and the ECB is a mag trip only?

 

[Smart $]

I think you need to research and comprehend what motor overload protection means, especially in the vain the NEC uses the term. Simply put, a typical inverse-time [thermal-magnetic] circuit breaker rated greater than pump motor FLA provides only short-circuit and ground-fault protection, and no significant overload protection.