NFPA 20: Fire water pump motor overcurrent protection

Status
Not open for further replies.

Bgg

Member
Location
Philippines
Occupation
Electrical engineer
Hi,

Can someone please elaborate/explain the clause in NFPA 20, see below:

9.2.3.4.1 (4) The trip point for circuit breakers shall not be field adjustable

I've been asking some fellow engineers regarding this clause and there were mixed ideas. Here are some interpretations:
  • the circuit breaker should not have adjustable trip units
  • the breaker can have adjustable trip units but once already set, it should not be adjusted at field and has to be locked.
In my case I needed a 400A circuit breaker for the fire water pump motor, but I could not find any non-adjustable trip.
Thanks for those who will share their ideas.
 

tom baker

First Chief Moderator
Staff member
Is this for a feeder to the fire pump controller?
I don't have NFPA 20, but the NEC wants the OC devices to be able to carry indefinitely the locked rotor current, and it also states the trip point is not field adjustable.
Whats good to keep in mind is the electric fire pump is sacrificial in the event of a fire.
 

Bgg

Member
Location
Philippines
Occupation
Electrical engineer
Is this for a feeder to the fire pump controller?
I don't have NFPA 20, but the NEC wants the OC devices to be able to carry indefinitely the locked rotor current, and it also states the trip point is not field adjustable.
Whats good to keep in mind is the electric fire pump is sacrificial in the event of a fire.
Yes, feeder for fire pump controller.
The statement "trip point is not field adjustable." - does this mean that the trip unit of the circuit breaker is fixed? Because for large circuit breakers we usually have adjustable pickup for long-time and instantaneous to fine tune the tripping.
 
Status
Not open for further replies.
Top