Fire Pump Normal Feeder

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steve holt

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How do I size my fire pump feeders. I have a 1400A Service SWBD that I am tapping off of, feeding a 1000A stand alone breaker enclosure. From the 1000A breaker I am feeding the normal side of the fire pump ATS/controller. The fire pump is 125HP and has a locked rotor rating of 909A and FLA rating of 142A. The feeder from the 1000A to the FP controller is currently 500MCM copper (I believe this is oversized unless 695(C) doesn't apply), and the feeder from the service SWBD to the 1000A is two sets of 900MCM copper. My question is, does the feeder tap from the 1400A to the 1000A need to match the 1000A overcurrent device rating, or can it be sized based on 695.6(C)1.? What about the feeder from the 1000A to the FP controller?
 
steve holt said:
How do I size my fire pump feeders. I have a 1400A Service SWBD that I am tapping off of, feeding a 1000A stand alone breaker enclosure. From the 1000A breaker I am feeding the normal side of the fire pump ATS/controller. The fire pump is 125HP and has a locked rotor rating of 909A and FLA rating of 142A. The feeder from the 1000A to the FP controller is currently 500MCM copper (I believe this is oversized unless 695(C) doesn't apply), and the feeder from the service SWBD to the 1000A is two sets of 900MCM copper. My question is, does the feeder tap from the 1400A to the 1000A need to match the 1000A overcurrent device rating, or can it be sized based on 695.6(C)1.? What about the feeder from the 1000A to the FP controller?
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Fire pumps are very confusing, but the feeder sizes are based on the 142 FLA all the way through, plus any auxiliary loads (695.6(B)(1)). If it's just to the pump see 695.6(B)(2), but keep in mind 695.7 and 430.22. Easy peasey. :p
 
You size conductors at 125% (+100% of associated equipment as Gadfly stated) of the FLA and the OCPD at 600%. There is also an option to use the locked rotor current instead of the 600%.
 
infinity said:
You size conductors at 125% (+100% of associated equipment as Gadfly stated) of the FLA and the OCPD at 600%. There is also an option to use the locked rotor current instead of the 600%.
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So this would apply to the conductors between my pre-service disconnect tap at the 1400A SWBD and my 1000A CB enclosure as well?
 
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