Fire Pump on Generator

[scottam99]

Typically a fire pump is wired directly to the power companies transformer without any breaker. As I was told it is so the fire pump will run no matter what, they would rather have it burn up than stop working in the event a breaker tripped. That being said. Why isn't it installed on the line side of the main breaker of a generator? If the normal power is interrupted and generator takes over and for what ever reason the breaker on generator is tripped/shunted etc. the fire pump would not be working. Interested on any thoughts about this.

 

[masterinbama]

Every fire pump I have installed had a breaker that was sized to carry the locked rotor amps indefinitely. I have never seen one with no OCP.

 

[DARUSA]

Usually Fire Pump disconnect switch (electric room)have fuses on it .
The fuse have to carry the LRC of the motor.
Fire pump have to be connected on the line side of the generator breaker.
Do you have transfer switch in your installation ?

 

[Smart $]

Every fire pump I have installed had a breaker that was sized to carry the locked rotor amps indefinitely. I have never seen one with no OCP.

Even the so-called direct connected fire pumps have ocp in the controller... but there is no ocp where the supply conductors receive power... either as a separate service or service conductor taps.

Where there is ocp between controller and remote power source, supervision is required.

 

[Smart $]

...
Fire pump have to be connected on the line side of the generator breaker.
...

Not required... but if it is connected to the load side, deductive reasoning would have the generator dedicated to this sole purpose: 695.4(A), in part...

Where the power source is supplied by on-site generator(s),
the supply conductors shall connect to a generator
disconnecting means dedicated for the purposes of serving
the fire pump. The disconnecting means shall be located in
a separate enclosure from the other generator disconnecting
means.​

 

[hillbilly1]

Generators are treated differently when it comes to fire pumps, they only have to be capable of starting and running the fire pump, not locked rotor. If other loads are on the generator, it must be able to run those and the fire pump at the same time. That is why a lot of engineers use shunt trip breakers to drop the non critical loads in order to use a smaller genset.

 

[scottam99]

In my situation the Engineer did not add a second breaker for the Generator. The Fire pump controller has a means of disconnect. If I wire to the load side of the breaker in the Generator panel then the fire pump is on a breaker with shunt trip. If the building shunt trip is activated All breakers are shunted including the generator

 

[hillbilly1]

In my situation the Engineer did not add a second breaker for the Generator. The Fire pump controller has a means of disconnect. If I wire to the load side of the breaker in the Generator panel then the fire pump is on a breaker with shunt trip. If the building shunt trip is activated All breakers are shunted including the generator

The fire pump can be wired ahead of the generator breaker, this is what the EE usually has us do. I had to design an interlock that would trip the shunt trip breaker when the fire pump starts while the generator is supplying the building and the utility has failed to the fire pump. You will have to have a short time delay built in due to the fire pump controller fails to the "ON" position during the transfer from utility to generator.

 

[cleveland]

We have installed two breakers at the generator, each one is in a separate enclosure located within the generator enclosure and have had no issues with the Fire Marshall on this situation. One feeds the life safety loads and the other feeds the fure pump.