Pump motor trips main GFCI breaker after 2-10 minutes

[dabaxter]

I have a 40A GFCI Breaker feeding a pool filter circulation pump, a polaris booster pump, and a pool fountain feature pump. Each is fed by it's own breaker downstream of the main 40A GFCI Breaker. The pool fountain feature pump is a whisperflo pump. It has a 3/4hp motor. It has run trouble free for years. Last spring the main 40A GFCI breaker began tripping. I replaced the breaker. This spring when I went to start using the pool fountain feature, the motor was failed and heaviliy corroded. I recently replaced the motor. When I turn on that pump, it runs for 2-10 minutes and trips out the main 40A GFCI breaker, but not the downstream individual breaker feeding it.
I can't figure it out. Any suggestions?
Thanks!

 

[ajw22]

Just to be clear - your main 40A CB is GFCI and the individual CBs for each pump are not?

Really it should be the other way around. Your 40A CB should be non-GFCI and each pump CB should be GFCI. The way you have it makes it difficult to diagnose GFCI trip problems. It also means each pump can have a bit of current leakage that would not trip a GFCI but when they all pass through the 40A GFCI it is enough in total to trip the GFCI.

Does the pool fountain feature pump trip the GFCI CB when the two other pump CBs are off?

 

[chubrok]

I recently had a very similar problem.. only my problem was with the motor for the pool cover. It has its own 20a breaker... Every time we would try to open the pool with it... the MAIN 100a breaker would trip and not the 20a breaker... I thought I had a bad 20a breaker.. but upon changing it out.. the problem remained. I checked all electrical connections all the way back to the main panel... all good.... Every other circuit for the pool had no problems. I then thought I might have a bad motor... upon removing the cover motor... I noticed that the electrical box (for the motor cover) showed signs of moisture. I disconnected the wires.. cleaned them up... and re-made the connections.... been going strong since. About a month later..(after a heavy rain) I had the same issue with my heater.. As soon as the heater would activate.. the main breaker would fail. I took my heater apart to find the main electrical connection.. sure enough ... there was water in the power box.... Dried it out.. re-made the connections...and good to go.. Not sure why its blowing the main 100a breaker and not the dedicated 20a breaker... but something to check out....

 

[tstex]

bax,

Allen has you covered - the main CB should be a standard non GFCI CB, while each pool pump should be on a dedicated GFCI CB.

I believe what's happening is your pool pump breaker [non GFCI] is not detecting the slight grounding of the corroded conductors, but once it goes past the std CB's, the GFCI CB is detecting it and doing its job and tripping. As stated, if your pool pump CB was a GFCI, then it should trip there and not impact your main breaker.

Turn off all pumps, then run each one of them one at a time for 10 mins and see what happens? Since your pump CB's are not GFCI, you're lucky your main breaker is or otherwise your "next of kin" could be posting this for you....

 

[dabaxter]

Thanks guys. It's been in that configuration for 20 years. I'd like to avoid the expense of replacing all those breakers. It trips whether the other pumps are running or not. If it tripped immediately, I'd think I've got moisture somewhere. The fact that it runs a couple of minutes makes me wonder could water somehow be getting to the motor.