Fire Pump Controller OCPD

[hbendillo]

I have read several threads concerning fire pump controllers and am still not clear on one thing.

In the scenario where a separate electrical service is provided for a fire pump and is fed directly into the fire
Pump controller, no service disconnect ahead of the controller, does the OCPD in the controller have to be rated to carry locked-rotor current?

The new service is fed directly from the POCO transformer.

Thanks.

 

[gadfly56]

I have read several threads concerning fire pump controllers and am still not clear on one thing.

In the scenario where a separate electrical service is provided for a fire pump and is fed directly into the fire
Pump controller, no service disconnect ahead of the controller, does the OCPD in the controller have to be rated to carry locked-rotor current?

The new service is fed directly from the POCO transformer.

Thanks.

The controller should be sized for the pump it's servicing. In that case, whatever the controller manufacturer puts in the cabinet can be assumed (yes, I know that can be dangerous) correctly sized for the pump it serves. Since the requirements for fire pumps involve both NFPA 70 (NEC) and NFPA 20 (Standards for the Installation of Stationary Fire Pumps), it's prudent to go with the recommendations of the folks who do this for a living. That said, per NFPA 20, the circuit breaker should be set to trip between 8 and 20 seconds at locked rotor current and be able to hold 300% of the FLA for at least 30 minutes. Instantaneous trip shall be set for not more than 20x FLA.

 

[hbendillo]

Thanks. Good information.