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#169880 - 10/18/07 10:36 PM GFCI Operation  
AndyM  Offline
New Member
Joined: Oct 2007
Posts: 6
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
Thanks


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#169884 - 10/18/07 10:55 PM Re: GFCI Operation [Re: AndyM]  
wire_twister  Offline
Member
Joined: Jul 2007
Posts: 265
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


Jimmy

Life is tough, Life is tougher when you are stupid

#169890 - 10/19/07 12:17 AM Re: GFCI Operation [Re: wire_twister]  
SP4RX  Offline
Member
Joined: Oct 2007
Posts: 56
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


#169892 - 10/19/07 12:58 AM Re: GFCI Operation [Re: SP4RX]  
gfretwell  Offline


Member
Joined: Jul 2004
Posts: 9,103
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.



Greg Fretwell

#169915 - 10/19/07 09:48 PM Re: GFCI Operation [Re: gfretwell]  
WESTUPLACE  Offline
Member
Joined: Mar 2004
Posts: 251
Kingwood, TX USA
Leakage may be thru the water lines not on the 3 prong.


#169917 - 10/19/07 11:01 PM Re: GFCI Operation [Re: WESTUPLACE]  
JoeTestingEngr  Offline
Member
Joined: Nov 2005
Posts: 785
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


#169918 - 10/19/07 11:43 PM Re: GFCI Operation [Re: JoeTestingEngr]  
twh  Offline
Member
Joined: Mar 2004
Posts: 916
Regina, Sask.
Perhaps a ground fault in a solenoid, or perhaps a bad GFI, or is it, in fact, a GFCI?


#170041 - 10/24/07 11:28 PM Re: GFCI Operation [Re: AndyM]  
AndyM  Offline
New Member
Joined: Oct 2007
Posts: 6
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


#170056 - 10/25/07 09:46 AM Re: GFCI Operation [Re: AndyM]  
Mike Wescoatt  Offline
Member
Joined: Jun 2001
Posts: 161
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.


Mike Wescoatt


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