I have a submersible pump 1/2 horsepower 425 feet from the breaker box. It is going down hill. What size wire should I run from the box to the pump. What is the best place to purchase the wire (mesquite, Tx), THanks WIll

What is the actual amperage of the motor, and more importantly what is the voltage?

If it is 120v you are in for some depressing advice.

230 v

Well, since you don't have the amperage we'll have to assume around 5 amps.

#12 would be within a reasonable range of voltage drop at 3.25%, but #10 would be better at 2.05%.

I would go to a real electrical supply house for the wire.

At this distance, DO NOT share this circuit with anything else. If you must then you absolutely need to go with larger wire.

So #10 would be ample for that distance

Yes it would.

It is a 5.5 amp full and a 6.3 amp something else on a 230v submersible pump. It is 440 feet from the breaker box to the pump. Nothing else running off it. I do not know if the increase in amps makes a difference. Thanks for your help.

#10 CU is the way to go!

Are you running your wires in conduit?
What type of wire are you running?

Wire that can be buried, 2 wrapped wires and a ground in a sheath