Fire Pump Service

[MichaelJ]

Can a fire pump control panel be feed through a dry type step up transformer? A 75 hp 460 volt 3 ph fire pump with fire pump control panel feed through a 112.5 kva 208 to 460 volt dry boost transformer served from utility transformer. Does the dry type transformer need to be service rated? Electrical engineer specified the wrong voltage fire pump and now had the electrician install a boost transformer.

 

[don_resqcapt19]

The requirements for fire pump transformers are found in 695.5.

 

[MichaelJ]

Am I correct that the transformer needs to be sized 125% of the sum of the full load amps and not the locked-rotor amps, and just the primary overcurrent protection is sized for the locked-rotor amps?

 

[MichaelJ]

And am I correct that a primary disconnecting means and overcurrent device is required?

 

[augie47]

Yes, The details are in 695.5 as don pointed out in post #2

 

[mayanees]

Am I correct that the transformer needs to be sized 125% of the sum of the full load amps and not the locked-rotor amps, and just the primary overcurrent protection is sized for the locked-rotor amps?

If the fire pump is across-the-line started the transformer size will depend on the 15% starting voltage drop requirement in 695.7(A) using the locked-rotor amps and will need to be larger than 125% of the fla.