GFCI Tripping

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Old 11-15-18, 06:02 PM
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GFCI Tripping

I have checked and replaced the GFCI, so Iím confident it is not the outlet itself.

I have a de-icing pump on my dock and as soon as the metal housing of the pump touches the water it is tripping the GFCI.
The outlet works fine otherwise. It runs the pump and other electric tools fine. Only when I place the pump into the water does it trip.

I sent the pump back to the manufacturer for service and they told me that they tank tested it and it had no issues with their GFCI outlet.
I used the pump on the same outlet last winter with no issues as well.

As I mentioned at the beginning of the post - I changed the outlet today for a new one and continue to have the same issue.

The pump is a Kasco 1/2hp de-icing pump.

Any idea what could cause this?
Thanks,
 
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Old 11-15-18, 07:21 PM
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I sent the pump back to the manufacturer for service and they told me that they tank tested it and it had no issues with their GFCI outlet.
That is not how a manufacturer should be checking a pump. It needs to be checked for leakage using an ohmmeter or a megger. A megger is a specialized test device that checks for leakage of motor windings and wiring insulation.

That pump has a leak in the windings to the metal case. It's possible it could cause your GFI to trip but not theirs. If that pump is under warranty...... it should be replaced.
 
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Old 11-16-18, 12:00 PM
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Thanks Pete.
I called the company again and they told me that they test everything with their (very expensive) megger.
Is there other possibility that would cause this to happen?
As I said, the outlet works fine on my power saw and the pump etc. only when the pump touches the water does the GFI trip.

They said to ship it back to them and they will check it again. (Another $40 expense to me)

Don’t freak out at me, but I took the GFI out and installed a regular outlet b/c I didnt know what else to do and the lakehouse is 4 hour drive away from home. Now I need to drive up and back again to retrieve the pump and send it back.
 
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Old 11-16-18, 12:55 PM
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Hmm, I wonder if they megg'd the entire pump assembly or just the motor. If the motor rings out OK, I'd suspect a small break in some other component like the cord, float/temp switch or something like that if it has one.

Are there any other electrical devices near the water when the pump is dropped in? Even on different circuits?

Do you have a multimeter to check other electrical measurements at the dock? For example is the voltage in nominal range of 120V under load?
 
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Old 11-16-18, 01:08 PM
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There is a lamp on the same circuit. They checked the cord (pointing out that the cord was not covered by the warranty if I did nick the cord).

I can pick up a multi meter, but don’t know quite how to use one. Is a cheap one ok, or should I opt for a better quality one. I’ve used cheapies from Harbor Freight, but that’s about it.

I’ve been running a pump off this circuit for years with no issues until now.

With instructions, i can check the measurements at the dock with a multi meter when I go back up to retrieve the pump. I’d like to eliminate any other possibilities.

Last thing I want is for them to check it again and have it be ok only for me to drive another 4 hours each way (uphill both ways!) to have the same thing happen.

Thank you for your help!
Mike.
 
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Old 11-16-18, 05:27 PM
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Not gonna freak out on you.

Get a meter before you go up. Let us know which one you get and we can tell you how to use it.
You'll want to check resistances between each prong and ground on the highest ohms scale.

Then I, personally, would sit the motor on the ground plugged in. Put the meter on AC/ over 120v scale. Touch one probe to it's case and the other probe to the water. You don't want to put yourself between the case and the water. There should be no voltage shown on the meter. If you see 120v then the pump is at fault.

I was trying to think if something could be wired wrong..... like no ground..... but nothing comes to mind. You don't need a ground at the GFI receptacle for it to work.
 
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Old 11-20-18, 08:56 AM
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Iíve got my tester and Iím on my way up to the lake.

I bought a Smithwire 10030S. Tester.

Looks like it measures resistance up to 2000k with the upside down U symbol if that is ohms?

Not it sure I know what you mean by the AC over 120v scale?

Im hoping I didnít give you too little notice to respond! Thanks again!
Mike




 
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Old 11-21-18, 02:39 PM
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It was a short in the outlet box

I went up to the lake yesterday.

i think I had a short to the ground within the outlet box that was causing the problem. I ended up removing cutting back 6Ē of the wiring and rewiring the gfi. Which seemed to correct the issue and the pump is working.
Iím very greatfull for all the help.
 
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Old 11-21-18, 07:23 PM
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i think I had a short to the ground within the outlet box that was causing the problem. I ended up removing cutting back 6Ē of the wiring and rewiring the gfi. Which seemed to correct the issue and the pump is working.

This tells me the GFCI woud have tripped before plugging the pump in and you said the GFCI didn't trip till the motor housing touched the water. This makes no sense at all.
 
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