Wiring for Sump Pump

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Loki

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Hello folks,

First of all, i would like to say that this forum is probably the best online resource for electrical questions and a big thank you to all those people who take time out if their busy schedules to answer questions.

Now to the issue at hand, I have a 2 HP sump pump that is being installed at the project site. The selection of the pump has not been finalized and depends on the answer to this electrical question. The existing panelboard that will feed this sump pump is a 120/208Y. There is a 2 pole 30A circuit breaker that is available to feed the sump pump.

What should the voltage requirement be for selecting the pump? Does the pump have to be single phase 240V? Correct me if i am wrong, but won't the phase to phase voltage be 208V if two breakers are feeding it from a 120/208Y panel. The wiring from the existing breakers have been already pulled in conduit and left for final connection at the sump pump location.
 
According to Table 430.248 a single phase 208 volt motor would have an FLA of 13.2 amps. Conductors would be sized by 13.2 * 125% = 16.5 amps so #14 THHN minimum. Using 250% for sizing your inverse time circuit breaker gives you a maximum ampacity of 33 amps which can be rounded up to the next standard size of 35 amps. IMO the 2 pole, 30 amp CB will work just fine.
 
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You don't have to flatter us to get us to answer your question. :) Welcome to the forum.

If you have to feed the pump with a 2-pole breaker in a 120/208Y panel, then yes you will be feeding it 208 V. You are correct about that.

Your only options (assuming that you only have 2 panel spaces to work with) are to use a single phase 240 V motor or go down to a single phase 120 V motor. With a 120 V motor, you would only need one space in the panel although you would need larger wire and a bigger breaker.
 
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