We have a new well pump installed . Since then the well pump trips the breaker only in the early morning hours when there is not a big load use on the pump . It does not trip in any heavy rain storms " under ground short you would think would increase. Any ideas? The pump is on its own 20 amp new square D breaker

Has anybody ever put a Amp-Probe on the wires when the breaker trips to see how many amps the pump's pulling? Back to you, Tom

Why would this only happen late night when water would not be running? Never happened when we would fill the hot tub or pressure wash all day. One would think this would happen at any time. This has been like this for 2 years and never filled the breaker when we were up only at night.

Is the pump the only thing on the breaker? That is probably the case, but stranger things have been known to happen.

More possible, do you have a water filter on the same circuit? Many filters are programmed to backwash at night.

Pump is only thing on its own circiut, water filter/ water softener / acid neutralizer in line

What size breaker is on the line?
the breaker only in the early morning hours when there is not a big load use on the pump Could something be setting up in the pump as it sets idle all night that puts an load on the starting coils? Just wondering. Tom

He said it's a 20 amp. But, as Tom suggested, I think measuring the amperage it's pulling would be worthwhile. Breakers are only supposed to run for long periods at 80% of their rated capacity, so that would be 16 amps on each leg for your pump. The 20 rating is just for short surges.

He said it's a 20 amp. Sorry I missed that. My bad! Do you think swapping the breaker for a 30 Amp would solve his problem? Let me know, Tom

If I was him, I'd ask an electrician about that. You don't want a breaker that is too large for the wire. According to the website below, a 30 amp breaker should have 10 gauge wire. Wouldn't surprise me if 10 gauge is run to the pump already, so if that is the case, then moving to a 30 amp breaker might be do-able.

http://groverelectric.com/howto/08_How%20to%20Calculate%20Breaker%20Wire%20Size%20&%20Wattage.pdf

Still doesn't answer the mystery of why it only happens at night. That is really strange. It will fill a hot-tub... no problem, but kicks off at night when it is seemingly not being used. I still would look at the backwash setting for that filter and see when it cut's on. If you can get a time for when it backwashes, and let's say it is around 2:00 a.m. then I'm getting up at that time (crud!) and listening for the breaker to throw.

I still like Tom's idea about measuring how many amps that pump is pulling.

Thanks I'll let you know what's up

Please do. We always like to hear how these cases are resolved.

We think the problem is solved they pulled the pump and rechecked the new wireing, then replaced the pressure switch at the tank. They saw the one that they replaced had a well Pump switch that had a low water switch on it. We hope that it thought the water level was low and it switched off and through the breaker! Thanks every one this really had me stumped.

Hey Creek,
Thanks for the update. Glad you're all fixed up. Good luck, Tom