Fire pump excempted from Ground Fault

[poweringtech]

Isn't it dangerous if fire pumps are not required to have ground fault in a solidly grounded system of more than 150 volts to ground? The extremely high ground fault current may cause the fire pump to explode causing more problem than solution.

Excemption should be clear that if fire pump will have NO ground fault protection only if it is being supplied from an ungrounded system. Or an isolation transformer should be installed so that the system supplying the fire pump is either ungrounded or high impedance grounded to allow a single line to ground fault without damage to the fire pump.

 

[petersonra]

Re: Fire pump excempted from Ground Fault

i think the idea is that fire pumps should run when needed regardless of what damage would be done to the pump or surrounding environs, because the asumption is you really need to run the pump to put out the fire, and if the pump is damaged, who cares. thats why they put them in fire proof rooms.

 

[poweringtech]

Re: Fire pump excempted from Ground Fault

i think the idea is that fire pumps should run when needed regardless of what damage would be done to the pump or surrounding environs, because the asumption is you really need to run the pump to put out the fire, and if the pump is damaged, who cares. thats why they put them in fire proof rooms.

Hello Bob,

While the intention of the code is to put out the fire regardless of what happens with the fire pump motor.

Should the code be clear on this excemption?

Have a great day and God bless

I'm Bob too

 

[charlie]

Re: Fire pump excempted from Ground Fault

A ground fault is not a short circuit but a ground fault normally propagates to a short circuit. The concern for 230.95 is a ground fault in the switchgear that is feeding everything. 230.95 is not concerned about the downstream circuits if the overcurrent devices are chosen properly. Additionally, the fire pump circuit will likely open under fault conditions and it is also considered to be outside the building because of the way the circuit is run to the fire pump.

The fire pump motor is behind the motor controller that will open the circuit after 20 to 30 seconds of locker rotor current. It will take longer than that to catastrophically destroy the motor.

The bottom line is that the fire pump motor is protected as much as it can be and still be available to pump every drop of water it can to save the building.