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Answering Your Water Pump Questions

with RPS Engineer Mike

What Size Breaker Do I Need for My Water Pump?

What Size Breaker Do I Need for My Water Pump?

We're always going to suggest that you consult with an electrician if you're uncomfortable figuring this all out yourself. But we'll try to get you started in the right direction! For a 220V submersible well pump, you'll size the breaker by the pumps rated horsepower. 

Breaker Rating By HP

HP

Volts

Circuit Breaker Amps 

Standard Fuse Amps

NM-B Wire Gauge Necessary 

½ HP

220V

15

15

14ga

¾ HP

20

20

12ga

1 HP

25

25

10ga

1.5 HP 

30

30

10ga

2 HP

30

30

10ga

3 HP

45

40

8ga 

5 HP

70

60

4ga

Wiring rating for up to 100 feet of wire, if using more than 100 feet, use next largest gauge of wire. Safe maximum of amp drawn on breaker is 80% rated value of breaker. 

Check that the fuse or breaker is sufficient amps for powering the water pump. If you’re replacing an old pump with the same HP of new pump, the breaker rating should be fine. If you are replacing with a greater HP, you may need a breaker with a higher rating. The breaker panel should have a wiring assignment on the inside of the front door, use this to identity which circuit is your submersible pump and de energize the circuit before installing. You should see that the breaker takes up two adjacent spaces, identifying it as a 220V system, a single breaker would mean that the breaker is only a 110V.  

UF-B direct burial or THHN/THWN wire pulled through conduit are suitable methods of wiring the starter box to the breaker. You must comply with local electrical and building ordinances when installing wire to the breaker.

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