My pool pump has sub-panel with a 50A 240V GFI Circuit Breaker.

It was not coming on this morning.

First
-----
The breaker, which also has a GFI, wasn't tripping but I measured no
voltage at the load side.

I looked at the pump wiring which was all fine.

If I pushed the Test button then the breaker tripped.

A little later
--------------
I did nothing, but then the breaker would not trip even pushing the Test
button. Still no output on the load side. The load was still connected.

A little later
-------------
The breaker would trip immediately even with the load disconnected
completely.

Fourth
------
I bypassed the breaker temporarily and the pump comes on (there is still
another breaker at the main panel but not a GFI breaker so it was okay
for a few seconds).

So I wonder if this is just a bad breaker or if I'm missing something.
It's over $100 for a replacement. I ordered one because I can't imagine
what else it could be since it trips with no load connected.

This is the breaker: http://www.amazon.com/dp/B001PWC17M

Couldn't find one in the SF Bay Area at any price, but I found a
supplier in Sacramento for $102 plus tax and shipping.

I was thinking of putting in a fuse block temporarily with two 50A fuses
while waiting for the new breaker. There would be no GFI protection but
it's no big deal for now. We are not using the pool and no one touches
the equipment but me.


I don't know your exact situation, but you may not need the 50 amp breaker to be a GFCI. You can put in a regular breaker and change the load breakers to GFCI or change the outlet(s) to GFCI.

It's possible that the insulation on the wire is breaking down and moisture is causing a ground fault. My guess though is a bad GFCI breaker.

John Grabowski
http://www.MrElectrician.TV