Too small a temperature swing on the thermostat can cause this issue as well. Many electronic thermostats have an adjustable temperature swing of 0.5, 1, 2 degrees. If this value is set too low and the compressor is restarted too soon (less than 10-15 minutes) after a cycle, it can trip a breaker as the compressor struggles to start against a pressurized system. This setting is also known as differential, anticipation, or hysteresis.
Was the motor replaced with the same size (horsepower, amperage, voltage) motor? What is the amperage and voltage listed on the motor's data plate? In many cases the motor plate will either list the size of the required breaker, or if not, the manufacturers website will have that information available. If you "had the motor changed" it might be best to call the company that changed it and report that the new motor is tripping the breaker, where the old one did not, and have them check for issues, since they should have verified that the new motor would work the same, or made any changes needed to support any change in the motor. If you changed it yourself, that's on you.
You should not replace the breaker with a larger breaker unless the new motor requires a larger breaker.
You should not replace the breaker with a larger breaker without ALSO replacing the wire with larger wire, suited to the size of the larger breaker, which should be suited to the size of the new motor. 20 amp, 12 gauge copper, minimum - 30 amp, 10 gauge copper, minimum.
Rather than "sanding the wires" you should (with the breaker off, of course) cut off the damaged ends of the wire, pull it a little further in, and strip the ends to get new undamaged wire. If this is not possible, consider replacing the wire, especially if it's fairly short run.
110V (single-pole breaker?) is rather abnormal for most well pump installations. One potential fix would be to re-wire for 220V operation if possible
Best Answer
First simple answer, you may want and or need to call an electrician since a short can lead to a fire.
Simple things you can do first:
Make a list of EVERYTHING that is on the breaker downstream
Add up all of the rated labels for every component
Make sure you truly have EVERYTHING listed. Keep in mind, chandelier lights, with 12 bulbs in them, and 40w each bulb is actually pulling 480W.
4.For anything that is a major appliance or heavy motor or heat load add 25% to its label for good measure
Total the items up, if you are over 75% of a 15AMP circuit for example, you should really re-balance your loads. This is really a safety concern and the fact that it worked for x amount of time and now is causing issues is a real concern. Over time, drawing too much current from a circuit causes the wires to expand and contract, and can even break down the metal wire & contacts, from burning and oxidization. Also, plastic parts that hold those metal contacts can melt, warp, or become brittle and break. Thus, your short *(or high current) situation.
Are any of the items plugged in or connected via cords exposed to people or pets? Check the cords for frayed or broken conductors, feel exposed cords for any warmth - the should not be hot
Of the list of items you made, are any on a duty cycle? Like a sump pump, a fridge, an A/C, an outdoor flood lamp?
Has any part of the home been remodeled or have any switches been intermittent at all? if so, then they need to be inspected or replaced, or the workmanship checked.
Any of the items on the list themselves behaving erratically? Any unusual smells from a Fridge or an A/C etc can be signs of a fault in the appliance/component.
If these things all check out, and the load on the breaker is not at 75% or greater before any changes are made, then it is probably a bad breaker. They can go bad! What is the age of the home and the wiring?
A side note: if the house has aluminum wire or has been remodeled at all, have a professional check it. There are specific methods that can be employed to keep aluminum wiring safe but it has to be done correctly. Conversely, if something was remodeled, they should own/warranty any work they have done.