Feeder Size

[Alwayslearningelec]

Tapping line side service switchgear and feeding an 1800AS which feeds an ATS/fire pump controller and fire pump.

Don’t have size of gear or ats. Fire pump only says 250HP. Not even sure of voltage yet. Not much info given.

Assume I need more info than just 1800A to make sure feeder sized correctly?

 

[infinity]

So your tap is actually service conductors to a large service switch. From there is goes to the fire pump controller/ATS? The 1800 sounds like the fuse size. 302*600%=1812 amps.

 

[Alwayslearningelec]

Yes.

 

[infinity]

Yes.

View attachment 2576611

Okay so what's the question? The "tap" conductors to the switch are sized at 125% of the FLC of the fire pump.

 

[Alwayslearningelec]

Okay so what's the question? The "tap" conductors to the switch are sized at 125% of the FLC of the fire pump.

Yes so I don't know the fla of the pump which I need ..correct ?

 

[infinity]

Yes so I don't know the fla of the pump which I need ..correct ?

You need to know the HP rating of the pump which you have. The FLC comes from T430.250.

 

[Alwayslearningelec]

Ahhhh right. I forgot. Is that what one uses regardless of what nameplate says?

 

[infinity]

Ahhhh right. I forgot. Is that what one uses regardless of what nameplate says?

Yes. Under the NYC electrical code the typical setup for fire pumps is service conductors to the service switch sized at 125% of the FLC. Fuse size is 600% of FLC. Conductors to the fire pump controller 125% of the FLC in a 2 hour rated wiring method.

 

[augie47]

Fire pumps are one of the few areas where the Code requires you to address voltage drop so you really need the motor details to assure you have an adequate feeder