Ivan wrote:
Sometimes, when I start my pool pump motor, it turns for a few
revolutions, then pops the circuit breaker. Other times, it starts
and runs normally. This is not a case of clogged skimmers. Before
the breaker pops, I can run the electric light in the pool shed--the
breaker only pops when I switch the motor on.

The motor is ju-u-u-st out of warranty --installed May '09. Before I
spend $370 replacing it I want to be sure it's the motor and not some
electrical glitch in my wiring, or a problem with the pool pump. Any
suggestions?

I have a 220V compressor that would cycle well for awhile, then randomly trip
the breaker. It finally quit starting. Turn on the breaker, and it would just
buzz loudly. I cleaned the starter switch contacts - no help. Tracked down the
bad starter capacitor and replaced that, both problems seem to be solved. $13 at
Grainger for the part.

You can check the capacitors with an ohmmeter. A good one will show a gradual
reading rise from when you touch the leads to the capacitor. Reverse the leads,
and the reading goes negative, then gradually climbs into the positive readings,
until it finally reaches the bleed resister value, or off scale if no resister.
A bad Cap will change quickly if open, it not at all is shorted.