Gfci

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Several years ago, I came across a situation at a big-box retailer where turning on an Advance T8 florescent ballast caused the near simultaneous GF trip of its circuit breaker and seven other SquareD GFCI breakers in a 42 ckt QOB panel.

I one-lined the circuit and it was dedicated to the ballast in a new display case. Somehow the ballast was tripping the other GFCI's from the line-side. I changed the ballast to a Triad or such and the tripping stopped.

In the OP's situation, there doesn't appear to be a switched load on a different circuit that is causing the trip. But I've never seen this occur at a GFCI receptacle.
 
Does the GFCI trip with no load and refuse to reset, or does the unit just trip once upon installation and the resets OK?

If the unit won't reset, the only thing I could think of doing would be to remove the ECG and see if the unit holds. If so, I would suspect a problem with an upstream neutral to ground or receptacle wired backwards and used as a junction.
 
GoldDigger said:
Low resistance connection (downstream bond) between neutral and EGC, even on line side, might cause a trip?
Click to expand...

Possibly in new ones that self test. Just for curiosity sake, I would shut off the breaker, remove the hot wire, ground it to the buss and test resistance at the receptacle. If Hot to N is at all different than Hot to ground, the GFCI may sense that and trip.
 
GoldDigger said:
Low resistance connection (downstream bond) between neutral and EGC, even on line side, might cause a trip?
Click to expand...
You still have no current imbalance through the sensing CT of the GFCI. My only thought (if something isn't being held back from us) is there is inductive kickback on the supply circuit that the GFCI doesn't like.
 
Just spent the better part of an hour and a half %^&*ing with one of these GFCI. Was working fine, added one more keyless light in the attic, it holds, get everything back in boxes, one minute later, GFCI trips. Resets fine, few minutes later it trips again. The lights were wired from the load side; the line side and EGC all wired correctly. I could see it maybe tripping when I pushed the devices back in the boxes, and maybe touched neutral/ground, but minutes later? I took the lights off the load side and wired them pass thru. I did not further test the receptacle with any loads -this was supposed to be a 15 minute job for a friend... I did check the GFCI again before I left, some 20 minutes after I finished, was holding with no load. Was already pushing 110* in that attic...


I'm thinking the self test on these is faulty/overly sensitive or maybe the attic heat has already partially damaged the receptacle electronics. afaik, any properly functioning GFCI that senses a ground fault locks out more or less instantly, not minutes later, and would not reset if there were a true ground fault.

My apologies to the OP for suggesting a wiring error. I wired all of the lights and receptacle myself only a month ago, and used an NM stripper for the sheaths, not a razor knife, so there is almost zero chance there is a damaged neutral that just so happens to be touching ground or hot. Boxes are plastic. Wire run past GFCI maybe 70' total. When I go back I will get the make/model of the GFCI.

eta: just thought about this: 4 of the lights are on one side of a 3 way and the last light is on the other traveller terminal. maybe that 3 way is the issue...
 
jeremysterling said:
Several years ago, I came across a situation at a big-box retailer where turning on an Advance T8 florescent ballast caused the near simultaneous GF trip of its circuit breaker and seven other SquareD GFCI breakers in a 42 ckt QOB panel.

I one-lined the circuit and it was dedicated to the ballast in a new display case. Somehow the ballast was tripping the other GFCI's from the line-side. I changed the ballast to a Triad or such and the tripping stopped.

In the OP's situation, there doesn't appear to be a switched load on a different circuit that is causing the trip. But I've never seen this occur at a GFCI receptacle.
Click to expand...

I had a bath fan on a totally different circuit trip a GFCI device(s) that I tried. It was a relatively easy to find "culprit" for me though. I was there when it tripped as I shut the fan off plus it was repeatable.
 
readydave8 said:
I know you mean hooking line wires to load screws, but to me, polarity refers to "hot" and "neutral" (ungrounded and grounded) connections
Click to expand...

I think he means the neutral to the silver screw and the hot to the brass screw.
And of course lineside connected.
 
JFletcher said:
Just spent the better part of an hour and a half %^&*ing with one of these GFCI. Was working fine, added one more keyless light in the attic, it holds, get everything back in boxes, one minute later, GFCI trips. Resets fine, few minutes later it trips again. The lights were wired from the load side; the line side and EGC all wired correctly. I could see it maybe tripping when I pushed the devices back in the boxes, and maybe touched neutral/ground, but minutes later? I took the lights off the load side and wired them pass thru. I did not further test the receptacle with any loads -this was supposed to be a 15 minute job for a friend... I did check the GFCI again before I left, some 20 minutes after I finished, was holding with no load. Was already pushing 110* in that attic...


I'm thinking the self test on these is faulty/overly sensitive or maybe the attic heat has already partially damaged the receptacle electronics. afaik, any properly functioning GFCI that senses a ground fault locks out more or less instantly, not minutes later, and would not reset if there were a true ground fault.

My apologies to the OP for suggesting a wiring error. I wired all of the lights and receptacle myself only a month ago, and used an NM stripper for the sheaths, not a razor knife, so there is almost zero chance there is a damaged neutral that just so happens to be touching ground or hot. Boxes are plastic. Wire run past GFCI maybe 70' total. When I go back I will get the make/model of the GFCI.

eta: just thought about this: 4 of the lights are on one side of a 3 way and the last light is on the other traveller terminal. maybe that 3 way is the issue...
Click to expand...
Sounds like it is time to meg your circuit conductors.

I don't know all the in's and out's of the new self tests, but it is supposed to test the functioning of the device otherwise the ground fault sensing ability should have remained the same. I could be wrong but if it fails self test it possibly locks itself out and will not reset?

Your mentioned light on the traveler of a three way switching loop should not trip it as long as current doesn't leave the protected circuit.
 
When I typed polarity I meant black to brass and white to silver, or hot to hot and neutral to neutral. Honestly dont know if a GFCI would lock out if it were reversed, I think it would... it seems some field testing for my own education is in order.

Is there a technical term for a line/load reversal?

kwired, perhaps I should megger out the circuit. The 3 way *shouldnt* matter at all, even tho I have it wired unconventionally: in one position, 4 attic lights are on, new one is off, in the other, the 4 are off and the new one (with a pull chain switch) is on. The 3 way switch is rather high and cant be moved down any, so I added the 5th light with a long pullchain so that one doesnt have to completely enter a dark attic to turn on the lights. Yes, in either position, the current going out should equal what is going back (60x/sec), but I got to wondering if there isnt a slight leak to ground or another similar problem. Up until yesterday, I'd never seen a GFCI behave the way that one did, and it didnt start until I added the 5th keyless, which doesnt even require the EGC... what are the odds that there was factory damage in that 2' of cable I added, or that the two NM staples damaged the cable?

If it matters, originally the attic lights were going to be on 2 3 ways, as there is an interior and exterior entrance. The outside one is from the carport and needs a 12' ladder, so in the interest of saving $$$ and never using the outside entrance for entry, the HO deleted it after I bought the switches. I took one back but used one 3 way as a snap switch. It is now wired as described above.
 
I would like to echo this question from post #5:
mgookin said:
What's new?
Click to expand...
I would ask the owner whether this particular GFCI receptacle had been in service for several years, with no new electrical work being done in the house for several years, and the symptom suddenly appeared. Or did the owner recently have the kitchen completely remodeled, and did the symptom show up immediately thereafter? What is new? What changed? That kind of information could easily point you to the culprit.

 
JFletcher said:
When I typed polarity I meant black to brass and white to silver, or hot to hot and neutral to neutral. Honestly dont know if a GFCI would lock out if it were reversed, I think it would... it seems some field testing for my own education is in order.
Click to expand...

Reversed polarity will not trip nor lock out any of the GFCI receptacles that I've seen
 
Thinking about it some more, I do not think any GFCI receptacle will be designed to trip or lock out on reversed polarity, since we can use them on ungrounded circuits.
 
kwired said:
...
I don't know all the in's and out's of the new self tests, but it is supposed to test the functioning of the device otherwise the ground fault sensing ability should have remained the same. I could be wrong but if it fails self test it possibly locks itself out and will not reset? ...
Click to expand...
The standard that requires the GFCIs to be self testing permits the device to lockout on a failed test or to provide and audible and/or visual alarm.
 
Is there any possibility of a RF source in the area? Strong RF signals can trip GFCIs, but the newer ones have much more resistance to this than the older ones.
 
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