Pump tripping GFCI outlet

[GregN]

Hi All - I have a Hayward power flo matrix 1 HP 2 speed pump I purchased new in August 2019. I run the pump on low speed approximately 11 hours a day via a simple intermatic outdoor rated dial type timer (the kind with the circular dial and on/off pins). Pump is plugged into timer, timer is plugged into outlet.
Pump was running fine all day yesterday. I noticed this morning that it was not on. The pump is plugged into a dedicated line fed by a 20 amp breaker that runs to dedicated single pole GFCI outlet. I noticed that the GFCI red light, that is on when outlet is working, was off. I unplugged timer from outlet, reset GFCI and light came on. Plugged in cord from timer and it immediately tripped the GFCI. I removed the timer, reset GFCI, and plugged pump directly into outlet and it tripped, even with the pump switch in the off position. I grabbed a floor fan, reset the GFCI, and the fan operates. I plugged the pump into another outdoor outlet on a different breaker and it also trips the GFCI.

I removed pump from plumbing and inspected impeller, and as best I can tell (hard to reach into hole) the impeller does move/spin.

I know motors can be tricky to diagnose, but are there any "easy" things I should check first?

Thanks,
Greg

 

[phonedave]

If you had a stuck impeller that would overload the current on the circuit and trip the breaker. The GFCI is senses the amount of current coming in on the black wire, and the amount going out on the white wire. If there is a difference, that means current is going somewhere else where it should not (potentially through a person) and it trips. That is a bit of a simplistic description because this is AC not DC, but idea is sound.

Something on your pump is bleeding current to ground. Since this is a dedicated circuit and not a branch or a subpanel, we can skip over improper bonding of equipment grounds and neutrals. Since the motor also trips a separate GFCI and the timer and fan does not trip the original GFCI, then we can be pretty certain the issue is with the motor. You can (with the motor unplugged) ohm out both the hot and neutral to the ground and to the motor chassis and see if there is an issue there. If you have access to a megger you could also test the insulation breakdown on the motor winding. Something in the motor likely has a high resistance short. GFCIs are very sensitive and even a high resistance short will bleed off enough current to trip it.

 

[ajw22]

Good chance the pump has a water leak through the shaft seal into the motor that caused enough corrosion to trip the GFCI.

Anything you do begins with removing the motor from the pump and examining it. See if there is a motor repair shop around you who will look at it.

 

[GregN]

Hi Phonedave - tx for reply. Just to confirm, the 20 amp breaker is not tripping, just the GFCI at the outlet. I have a meter, but I'm not as familiar with using it in ohm mode...I might have to call in a buddy to help me follow your suggestion.
Tx-Greg

 

[phonedave]

Hi Phonedave - tx for reply. Just to confirm, the 20 amp breaker is not tripping, just the GFCI at the outlet. I have a meter, but I'm not as familiar with using it in ohm mode...I might have to call in a buddy to help me follow your suggestion.
Tx-Greg

Correct.

The breaker (if it is a normal breaker) trips because of a current overload. Something is drawing too much power.
The GFCI trips because of a current IMBALANCE. Current is leaking somewhere it should not.

You mention the impeller spins free. If the breaker was tripping, then I would say look at the impeller. A stuck impeller, or a bent shaft, something that puts excessive load on the motor could cause the BREAKER to trip. Since the breaker is not tripping that is likely not the issue.

Here is a start on how to ohm out your motor

How To Test and Check Single phase Electric Motors

Single phase motors test, insulation resistance,

www.electricalengineeringtoolbox.com

Note that you cannot conduct the insulation resistance test with a regular multimeter. You need a Insulation Test Meter, a Megaohm meter, or sometimes referred to as a megger.

A megger will put high voltage (2000 volts or so) on the circuit. The high voltage will breakdown a high resistance fault and find any slight problems with the insulation in the motor.

Ohms mode on your meter just measures resistance (instead of voltage).

 

[GregN]

Well, i guess I got lucky. Instead of waiting for me poke around with the multimeter, my wife called the local pool store and learned that they service Hayward pumps and parts available for most repairs. I few hours later I got call from their shop indicating they had opened it up and has the motor on the bench and it was running fine. There was some corrosion around the impeller shaft seal, I think he mentioned a ceramic washer or part, and thought a new seal kit would fix the issue. Anyway, they only charged me 28 bucks total and I picked it up this AM, re-installed it, and it is running fine. It's REALLY nice to know there still exists honest people not looking to take advantage of others.

PhoneDave/AJW22 - just wondering, does the repair make sense in terms of being the cause of the tripping GFCI?

Thank you both for your responses and advice. PhoneDave, I am going to get more versed in using my meter.

Greg

 

[phonedave]

Well, i guess I got lucky. Instead of waiting for me poke around with the multimeter, my wife called the local pool store and learned that they service Hayward pumps and parts available for most repairs. I few hours later I got call from their shop indicating they had opened it up and has the motor on the bench and it was running fine. There was some corrosion around the impeller shaft seal, I think he mentioned a ceramic washer or part, and thought a new seal kit would fix the issue. Anyway, they only charged me 28 bucks total and I picked it up this AM, re-installed it, and it is running fine. It's REALLY nice to know there still exists honest people not looking to take advantage of others.

PhoneDave/AJW22 - just wondering, does the repair make sense in terms of being the cause of the tripping GFCI?

Thank you both for your responses and advice. PhoneDave, I am going to get more versed in using my meter.

Greg

It could very well be. A class A GFCI trips where there is a difference of 4 to 6 milliamps. It is not like it needs a dead short to ground and sparks flying to trip it. If the interior of your motor was getting damp from a leaking seal, that moisture (especially pool water) could very well conduct enough electricity to trip the GFCI. I am glad it worked out for you.

A meter is a very useful tool, for lots of things.

Thanks