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Ronnie1a 08-26-2008 09:15 PM

Underwater pump knocks out GFIC switch
I have a small 110v underwater pump that recirculates water in a waterfall/pond. It will normally go for weeks with no problem then trip the GFIC breaker it is plugged into. Nothing else is attached to the plug. Other times it will run from 1/2 a day to 10 minutes or less and then trip the breaker. The water is clean so the pump, itself, is not working any harder than it ever did. I don't know what to look for. Do they make a "stronger" GFIC plug that will not trip as easily?

Silk 08-26-2008 09:34 PM


Originally Posted by Ronnie1a (Post 152132)
I don't know what to look for. Do they make a "stronger" GFIC plug that will not trip as easily?

Not for your situation, the trip range to protect people is 4-6 milliamps.

Speedy Petey 08-27-2008 06:10 AM

In your situation there are two possible scenarios:

1) Pump going bad.
2) GFI going bad.

It's tripping for a reason! (not just to annoy you)

fw2007 08-27-2008 08:56 AM

GFCI is intended to trip when there is a differential in current between hot and neutral wires. Such a condition will exist if there is current leakage to earth ground (sometimes through you!)

Is this underwater pump on a GFCI receptacle, or a GFCI circuit breaker?
If it's a receptacle, the issue isn't current draw, it is leakage to ground.
If it's a breaker, it could be either, however, I don't suspect that the pump would draw more than 15Amps to trip the breaker, so the issue must be a GFCI issue.

The following may be a bit of work, but it is probably what I would want to try:

Could you remove the pump from the water, and check for voltage to ground from the housing using a voltmeter (with the pump running)? Be very careful when doing this, since the case might have voltage on it, and you could be shocked by touching it!

If the pump housing is grounded via a 3-prong plug, you might have to use a "cheater" adapter to temporarily disconnect the ground, so that you can measure the voltage on the housing.
Then, touch one lead of your voltmeter to the housing, and the other to a known good ground.

I would recommend doing this test on a workbench, indoors, not outside.
I also recommend plugging the pump into a GFCI protected circuit for the test.
You shouldn't trip the GFCI when using the voltmeter, since it draws almost no current.


J. V. 08-27-2008 10:55 AM

I would put my bet on either the pump or the wiring to the pump. If it's plug and cord just take it out and try a new one.
It could be the GFCI but not likely. Pick one up just in case.

Cow 08-27-2008 06:19 PM

That's the problem with DIY electrical, they just don't have the test equipment to diagnose the problem properly and the "guess and replace" method is expensive. If only he had a megger....

So, it's either a weak breaker or faulty wiring/pump. I'd probably guess the latter unless the equipment is new.

J. V. 08-28-2008 12:14 PM

Cow, yep I agree. It can get expensive to use the trial and error method of troubleshooting. In this situation IMO it is much easier and safer just to replace. He might be able to return the parts he does not need.

OP: Keep receipt, open carefully so you can rebox it and wipe it off good so the merchant can just put it back in the inventory.

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