Have a submersible pump and the breaker keeps tripping. This happened twice last week during a cold snap but only once per occasion where the breaker would stay on after resetting.
Now the breaker immediately goes to the middle after resetting. Disconnected the wire from the house to the pressure switch - still kicks off. How would I test the buried cable for shorts? It is approximately 500' long. Do breakers go bad? Crossing my fingers hoping for a simple (inexpensive) solution.

You can test for continuity between the two wires going to your pump. Disconnect the power first! First try testing your tester by touching the two probes together. It should beep or light up. If that happens when you try the hot and neutral wires that feed your pump, your wires are bad. If they are good, you may have a failing breaker. Hope this helps.

Where are the tank and pressure switch?

Tank and pressure switch are out at the well house. Wire runs from house breaker box to a junction box underneath the house, out to a splice, then out to the well house pressure switch. Then from the pressure switch to the well pump controller box.

Before you get all excited about that splice, it's been disconnected so we could test the breaker. The breaker stayed on. As soon as we connected it back again, it popped the breaker. From that splice to the well house, it is one piece of wire, no more splices.

The splice was where the line was extended from an old house (that we tore down) to the new house that we built. The splice is still exposed, so I may test after it to the well house for continuity. After I rest up a bit. And if the well guys don't get here first. Why the bloddy buggers do things like this only happen on Sundays?

Too bad we can't post pictures on this forum. I'd show you gents that a guy in a wheelchair can indeed dig out the underground wire. Shows what you can do when you get desperate enough!

Thanks for the advice, I'll repost later.

Well, obviously the problem is in the underground wire, between the splice and pressure switch. Your task is to find it. :)

Gents, the task is done. Well, the workaround anyway. The expensive option.

The well pump guys came out and tested the wire six ways to Sunday. The break is somewhere under 24inches of dirt for 500 feet. Any takers??

No, didn't think so.

They ran a new wire and we now have water. Awaiting sticker shock from the bill they will send. Maybe I should change my address real quick.

Great forum, thanks for all the replies.