Can I splice large wire for long runs


I have a pump that is 350 ft from my house. Here are the specs for the pump:

Rated power – P2: 1 HP
Main frequency: 60 Hz
Rated voltage: 1 x 115 V
Maximum current consumption: 8 A
Power plug: US plug 115V

The breaker is a 20 amp GFCI breaker (I can't seem to find good GFCI breakers that are Square D larger than 20 amp). I know from calculators that I need larger than 10/2 wire, but I ran the 350 ft with some 10/2 ufb wire anyway, to see if it would work ok. I did this because I already had the 10/2 wire. It works intermittently, but I've stopped using it because I don't want to damage anything. I'm getting mixed signals based on which electrical calculator I use saying I either need #6 or #4. Wire's insanely expensive, but I need this pump working.

I know there are other alternatives like running 240v, but I can't seem to find a step down to 120v that will be happy in an outdoor environment. So, ignoring the fact that I could run 240, with a step down, how can I accomplish this?

Is it ok to keep the 10/2 on both ends (since the wire is about as small gauge as I can get and still get it inside the boxes I need easily) and splice 300+ ft of #4 or #6? I'm not sure how the splicing would effect the run.

And assuming splicing is ok for this…..since it's hard to find 500ft 6/2 wire in ufb, and I need 300ish feet, would it be ok to buy a few 125ft lengths and splice them?

Best Answer

Your run is too long for your GFCI

Your GFCI is tripping, not necessarily because your pump is faulty or your GFCI is broken, but because you are well outside the 250' maximum cable length limit in your GFCI's instructions.

As a result, you'll want to get a small encapsulated (NEMA 3R rated) 240V/120V stepdown (1500VA is fine) and put it out by the pump location, then use a "spa panel" sized breaker panel to house the GFCI there, with a 2 pole 15A breaker back at the house to protect the transformer and run.