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#169880 - 10/18/07 07:36 PM GFCI Operation
AndyM Offline
New Member
Registered: 10/18/07
Posts: 6
Loc: Quincy MA USA
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
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#169884 - 10/18/07 07:55 PM Re: GFCI Operation [Re: AndyM]
wire_twister Offline
Member
Registered: 07/25/07
Posts: 265
Loc: Georgia USA
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
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#169890 - 10/18/07 09:17 PM Re: GFCI Operation [Re: wire_twister]
SP4RX Offline
Member
Registered: 10/01/07
Posts: 56
Loc: Edmonton, Alberta, Canada...eh
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
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#169892 - 10/18/07 09:58 PM Re: GFCI Operation [Re: SP4RX]
gfretwell Offline


Member
Registered: 07/20/04
Posts: 9036
Loc: Estero,Fl,usa
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.

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#169915 - 10/19/07 06:48 PM Re: GFCI Operation [Re: gfretwell]
WESTUPLACE Offline
Member
Registered: 03/29/04
Posts: 251
Loc: Kingwood, TX USA
Leakage may be thru the water lines not on the 3 prong.
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#169917 - 10/19/07 08:01 PM Re: GFCI Operation [Re: WESTUPLACE]
JoeTestingEngr Offline
Member
Registered: 11/04/05
Posts: 781
Loc: Chicago, Il.
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
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#169918 - 10/19/07 08:43 PM Re: GFCI Operation [Re: JoeTestingEngr]
twh Offline
Member
Registered: 03/11/04
Posts: 901
Loc: Regina, Sask.
Perhaps a ground fault in a solenoid, or perhaps a bad GFI, or is it, in fact, a GFCI?
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#170041 - 10/24/07 08:28 PM Re: GFCI Operation [Re: AndyM]
AndyM Offline
New Member
Registered: 10/18/07
Posts: 6
Loc: Quincy MA USA
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
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#170056 - 10/25/07 06:46 AM Re: GFCI Operation [Re: AndyM]
Mike Wescoatt Offline
Member
Registered: 06/17/01
Posts: 161
Loc: Cedar City, Utah
Was it a different brand or the same brand? I've seen different brands with different tolerances that still meet the UL listing.
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