Hello , I live on a water reservoir and pull water off it and treat it for my home. the wire run ranges from 500 to 800 ft depending on the lake level. I had to replace the pump and put new one on. it a 3 wire with a ground 230 volt pump. this time I had to add more wire so I had to splice an extra 100 feet of number 8 gauge submersible wire to the wire run. now before this happened I had no problem with wire run I was using , the only thing that changed was adding a new pump and and an extra 100 feet of wire. when I put power to the pump I was at the power pole on shore and i watched the wheel spin around in the meter so the power is going some where but the pump is not pumping. So thinking I might have got a bad pump I brought an other one hooked it up and the same thing happened the meter speeded up spinning so power is going somewhere but no pumping . any ideas?

Bad splice causing a voltage drop? Does the pump manufacturer show maximum cable length by gauge?

I been pondering this all night and I think it a bad splice too. when I spliced in the extra 100 ft of wire I made two splices one that attached the wire to wire and one that attached the wire to new pump.Now I replaced the new pump with a different new pump so that splice should be good because it hard to believe I mess up the same splice twice. So I am going to re splice the wire to wire connection. if that doesn't do it my next step is to pull all the wire and check wire abrasion . after that I don't know

Are you using waterproof splices rated for underwater use?

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Not a plumber by trade but a fierce DIYer

Ok I had a water well guy come out and tried to run down the problem and when it was all done I spent money and the problem was not solved but he came up two facts. one he said my control box condenser was burn out. So, I took the old control box condenser to an electrical supply house to be tested and they said old condenser was good. I replaced the old control box on advice from a well guy on theory it is old and may be the problem. Sooo now I got a new control box that the guy I paid to find the problem says has a bad condenser. Since the control comes in two part, the back that has the wire and the front that has the condenser and a switch. so, I am now using the old condenser and the new wire box. the result is that the problem remains. once the breaker is thrown electric power is going somewhere but the pump is not working. a note on the control box, on the old box the condenser is wire directly to the third terminal which is named starter and on the new box the condenser is wire through the switch then to the third terminal which is named the starter. I don’t know if this is a problem. Right my plan is to pull the wire that the guy I hired says is bad or at least didn’t check and check for problems. thanks for any insight.