Fire pump protection

[anbm]

Fire pump controller/ats:

• Normal power circuit comes from a tap to poco transformer's secondary side without protection.
• Generator power circuit comes from a main emergency distribution panel (1st panel downstream of standby generator) and this circuit is protected by a breaker in panel.

Question:

• On normal power side (utility power), no breaker is needed, but per NEC, if a breaker is installed between xfmr and fire pump, the breaker needs to be sized to handle motor inrush current, i.e., CB size = 6 x fire pump motor's FLA.
• For generator power circuit, per NEC, the breaker to serve circuit to fire pump is not required to size to carry motor inrush current but = 2.5 X motor's FLA (article 430 for thermal magnetic breaker).

Question: when fire pump is on generator power, fire pump's inrush current never occur???

 

[don_resqcapt19]

The generator will not likely be able to start the fire pump without a large voltage sag that serves to act as a soft start and reduce the inrush.

 

[rafaelrobertson]

Fire pump controller/ats:

• Normal power circuit comes from a tap to poco transformer's secondary side without protection.
• Generator power circuit comes from a main emergency distribution panel (1st panel downstream of standby generator) and this circuit is protected by a breaker in panel.

Question:

• On normal power side (utility power), no breaker is needed, but per NEC, if a breaker is installed between xfmr and fire pump, the breaker needs to be sized to handle motor inrush current, i.e., CB size = 6 x fire pump motor's FLA.
• For generator power circuit, per NEC, the breaker to serve circuit to fire pump is not required to size to carry motor inrush current but = 2.5 X motor's FLA (article 430 for thermal magnetic breaker).

Question: when fire pump is on generator power, fire pump's inrush current never occur??? https://aperfectshinedetailing.com/

Is a fire pump required to have a rated separation from other spaces in the building?

 

[anbm]

Is a fire pump required to have a rated separation from other spaces in the building?

Separate room with fire rated wall? Yes.

 

[gadfly56]

Fire pump controller/ats:

• Normal power circuit comes from a tap to poco transformer's secondary side without protection.
• Generator power circuit comes from a main emergency distribution panel (1st panel downstream of standby generator) and this circuit is protected by a breaker in panel.

Question:

• On normal power side (utility power), no breaker is needed, but per NEC, if a breaker is installed between xfmr and fire pump, the breaker needs to be sized to handle motor inrush current, i.e., CB size = 6 x fire pump motor's FLA.
• For generator power circuit, per NEC, the breaker to serve circuit to fire pump is not required to size to carry motor inrush current but = 2.5 X motor's FLA (article 430 for thermal magnetic breaker).

Question: when fire pump is on generator power, fire pump's inrush current never occur???

The OCPD is sized for the locked rotor current, not the inrush.

 

[tom baker]

Most of the rules in Art 695 are extracted from NFPA 20. Suggest you get a copy of what ever version of NFPA 20 you AHJ has adopted

 

[ron]

In this arrangement, the generator is essentially a 702 source, not even a 701 source.

 

[anbm]

The OCPD is sized for the locked rotor current, not the inrush.

I stand corrected.