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GFCI Operation #169880 10/18/07 09:36 PM
Joined: Oct 2007
Posts: 6
A
AndyM Offline OP
New Member
I am a power electrical engineer & have learned (the hard way) that I am better at electrical work on paper then hands-on. I have had an electrican do some work at my house including replacing an old (~30 yrs) duplex receptacle that feeds a clothes washer. This outlet had no issues other then being old. He replaced it with a GFCI for the reasons of its in the unfinished basement. Unfortuntely the GFCI is operating when the washer is running. During 1 washing cycle it tripped twice.

As I understand the operation of a GFCI it monitors the line & neutral lines & operates if there is over a few millaamps difference between them. So I see that maybe the washer has some intermittent internal fault or short but do GFCIs have a know issue with false operations under certain 'non-fault' conditions?

I have the electrican coming back & I have stopped using the receptacle, but am more interested in getting more info for when the electrican comes back.

Thanks in advance for any info.

Andy
Thanks

Work Gear for Electricians and the Trades
Re: GFCI Operation [Re: AndyM] #169884 10/18/07 09:55 PM
Joined: Jul 2007
Posts: 265
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wire_twister Offline
Member
In my experience GFCIs sometimes will not run motor loads, nothing wrong with the load, or the gfci just some nuissance tripping. Solution: install a 20a single receptacle for the washing machine, per 210.8 ex 2


Jimmy

Life is tough, Life is tougher when you are stupid
Re: GFCI Operation [Re: wire_twister] #169890 10/18/07 11:17 PM
Joined: Oct 2007
Posts: 56
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SP4RX Offline
Member
The most likely scenario that I can think of would be that your washing machine's motor makes use of a capacitor. If that is the case then while the capacitor is charging (storing electrons) the neutral would be seen as having a different level of current, which the GFCI would interpret as a ground fault.
But then again I could be completely out to lunch! laugh

Re: GFCI Operation [Re: SP4RX] #169892 10/18/07 11:58 PM
Joined: Jul 2004
Posts: 9,571
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gfretwell Offline
Member
I say the washing machine has an internal short. All this "capacitor charging" and other excuses just do not pass the "Kirchoff" test.

If you are really brave/careful you could prove it by plugging in a 3 prong adapter and monitor the voltage between the ground and the pigtail on the adapter. I bet you see some. If you think this is just a phantom voltage make the connection to ground through a 50k resistor (not enough to trip the GFCI) and measure the voltage across the resistor. Just be sure you are not touching the washer when you are doing it.



Greg Fretwell
Re: GFCI Operation [Re: gfretwell] #169915 10/19/07 08:48 PM
Joined: Mar 2004
Posts: 251
W
WESTUPLACE Offline
Member
Leakage may be thru the water lines not on the 3 prong.

Re: GFCI Operation [Re: WESTUPLACE] #169917 10/19/07 10:01 PM
Joined: Nov 2005
Posts: 823
J
JoeTestingEngr Offline
Member
I've seen cases where folks have tried to put a GFCI in place of a duplex in a shared neutral circuit. Was your GFCI at the end of the line or were wires connected to the load side screws? The outlet will trip at the flip of a switch.
Joe

Re: GFCI Operation [Re: JoeTestingEngr] #169918 10/19/07 10:43 PM
Joined: Mar 2004
Posts: 947
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twh Offline
Member
Perhaps a ground fault in a solenoid, or perhaps a bad GFI, or is it, in fact, a GFCI?

Re: GFCI Operation [Re: AndyM] #170041 10/24/07 10:28 PM
Joined: Oct 2007
Posts: 6
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AndyM Offline OP
New Member
Here is an update. Looks like a bad GFCI. The electrican installed a new GFCI and it seems to be working fine. I have only run 2 full loads thru the washer, but the previous GFCI didn't last half a run.

Thanks for all the feedback.

Andy

Re: GFCI Operation [Re: AndyM] #170056 10/25/07 08:46 AM
Joined: Jun 2001
Posts: 161
M
Mike Wescoatt Offline
Member
Was it a different brand or the same brand? I've seen different brands with different tolerances that still meet the UL listing.


Mike Wescoatt

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