Short version
Is there some table that tells one how much HP an electric motor is and the gauge of the wire needed to run to it???
Long story
Our well went bad, losing pressure. We have been living in this house for 15 years without doing anything to it. Six of Dad's friends from work came over and pulled out the well pump as it was only 430 ft down.
Ta-Da
and specs
Note that there is a bunch of black tape that came loose. It's a 3/4 hp with 430 ft of 12 gauge wire going down the well, plus the wiring going to the electric box, so at least 530 ft of wiring at 12 gauge from the well pump to the panel.
According to the manufacturer's table from the service manual
the maximum wire length is 480 ft.
Clearly it wasnt an issue. Can a 1 hp be used as a replacement and the wiring be OK?? Or is the problem the well itself needing to be replaced?
Best Answer
There is some table, you appear to have found it, (though I don't know if you've found a "2-wire" or "3-wire" table - these days, "2-Wire" is a win, and black tape does not belong anywhere in a well, IMHO.)
...and you want our blessing it ignore it? If the pump "lost pressure" possibly from rust, not being stainless, evidently, possibly from ingesting black tape, possibly from 15+ years of wear - I tend to think in terms of "around 10 years, be ready to replace a pump" - the solution is to fix or replace it - adding a larger motor won't help, and adding a larger motor on undersized wire definitely won't help. If 3/4 hp got you adequate flow for 15 years, it will do so in the future, too - more horsepower is not always better, and often comes with a pump curve that may not work at your depth.
With a deep well and a relatively short topside run that's only slightly undersized, you can probably get acceptable voltage drop by leaving the buried wire alone and upgrading to 10 gauge for the longer downhole run in the well.
As to whether the problem is the pump (likely) or the well (possible) it's very hard to tell from afar - you either drop in a new pump and see what happens, or you hire a well company to come and evaluate the state of the well. There's not a lot that a homeowner can afford to do to evaluate a deep well OTHER than dropping in a new pump, and you can screw one up pretty good if you (say) try to evaluate the water level and end up dropping something down the well-hole. How far up the pipe was wet when the pump was pulled?