GFCI Circuit Troubleshooting

Status
Not open for further replies.
Receptacles go bad quite a bit, we find them not resetting, replace them, and all is well. Most of these are outdoor receptacles. Occasionally one is wired incorrectly (line to load and vice-versa, or a wire has come loose). Seen a few loose ones in metal boxes, someone plugs in an extension cord: trip. Unlike ActionDave, most of the ones I've seen fail from age/damage not bad equipment. Seen several with ground pins of cords broken off flush inside.

If it is a suspected equipment problem, use known good equipment (like your corded drill, or shop vac). If it doesnt trip the GFCI, it's probably customer equipment.

I've not seen a GFCI breaker fail so far.

eta: as for trips, I've seen some unexplainable ones. Older homes with bad weather resistant covers/boxes/receptacles can and do get water inside and cause a GFCI to trip. Replacing those outlets and making them watertight again usually works.
 
I have had enough that worked fine after replacing them that unless there is some obvious fault ( bad cord, ect..) I replace the GFI. 99% of the time that fixes it.
GFI breakers that trip right after installation are usually mis-wired neutrals somewhere in the circuit. Or just bad make-ups.
 
Most of the time if the device trips and will resett, they are working. Not resetting seems to be age related. The older ones liked lightning.

We typically replace the older ones even after checking the load side for faults because the replacement is a lot cheaper than a return call. A 10 to 20 year life for a GFCI device is acceptable.

The GFCI CBs rarely have a problem.
 
Reasons I have found for GFCIs tripping

Lying salesmen blaming the EC for installing GFCIs where they belong to protect personnel rather than admitting they sold the customer a defective piece of equipment. :thumbsdown:
Iron workers using long indoor extension cords outdoors laying in water.
GFCI receptacles installed below grade as specified by the architect getting covered with water and being expected not to trip. Outlets were readily accessible, but the architect wanted them pretty much out of sight .
Extension cords taped together by the GC to keep water out, but it did a great job of keeping the water in the connection.
Reliable eye witnessed Very nearby lightning strikes.
Badly weathered outlets.
Wet J boxes with splices.
Reverse polarity.
Florescent lighting connected downstream of GFCIs. (Not exactly sure why, but once it was replaced with 4' LED retrofits the problem went away.:? cheap ballasts maybe???)
Snow plows.
Folks hitting buried cables downstream of GFCIs.

IME most of the time they trip for a good reason, some won't reset after too many trips.
 
151218-2458 EST

WIMaster:

Fluorescent on turn off may produce a rapid rise (dv/dt) voltage spike from its inductive kick that is capacitively coupled to the SCR gate in the GFCI by a poor board layout.

There have been reports of bath fans doing tripping GFCI on turn on or off. Note there can be switch bounce on closure that causes arcing (the rapid voltage spikes) as well as when the switch is opened. Experimentally I have used an 8' Slimline to randomly trip a Leviton GFCI.

.
 
A brand new 48" two lamp T8 flour caused a GFCI outlet to trip. So did the next light(same model) we bought.

The light style is a shop light: it hangs from the typical two chains. It is cord and plug connected to an outlet that is on a circuit with GFCI protection provided via another outlet.

First idea was: get a new light but it also caused the problem. Both lights regardless of GFCI caused the fault.
*
Second idea is: We rearranged the circuit and provided a non GFCI source to the light. Supply house doesn't agree there is a problem. I intend to contact ballast mfg to see if they concur. AHJ says the light is non compliant if not able to operate on GFCI.

:?
 
gar said:
151218-2458 EST

WIMaster:

Fluorescent on turn off may produce a rapid rise (dv/dt) voltage spike from its inductive kick that is capacitively coupled to the SCR gate in the GFCI by a poor board layout.

There have been reports of bath fans doing tripping GFCI on turn on or off. Note there can be switch bounce on closure that causes arcing (the rapid voltage spikes) as well as when the switch is opened. Experimentally I have used an 8' Slimline to randomly trip a Leviton GFCI.

.
Click to expand...

To make it more fun the offending fan may not be on the same circuit as the GFCI device that trips, and the fixture that trips one brand of GFCI may not trip another's.

How did I manage to forget about my fan? It's only been 5 or 6 years.
 
151219-0921 EST

oceanobob:

Try a Corcom 5VR1 at the fluorescent fixture input. For RFI it better to install it within the fixture. This will reduce RFI (Radio Frequency Interference) and may reduce dv/dt enough to eliminate the GFCI trip problem. This Corcom is rated for 5 A.

.
 
When a linear fluorescent starts, there will be noticeable capacitively coupled current from the lamp tube to the grounded metal reflector. For some lamp designs that might be enough to trip a sensitive GFCI.
If an equivalent resistive load does not trip the GFCI. I would double check the sensitivity of the GFCI and maybe just replace the luminaire with a linear led or other alternative.
If the fixture without lamps installed does not trip, I do not think it is the ballast.
 
oceanobob said:
A brand new 48" two lamp T8 flour caused a GFCI outlet to trip. So did the next light(same model) we bought.

The light style is a shop light: it hangs from the typical two chains. It is cord and plug connected to an outlet that is on a circuit with GFCI protection provided via another outlet.

First idea was: get a new light but it also caused the problem. Both lights regardless of GFCI caused the fault.
*
Second idea is: We rearranged the circuit and provided a non GFCI source to the light. Supply house doesn't agree there is a problem. I intend to contact ballast mfg to see if they concur. AHJ says the light is non compliant if not able to operate on GFCI.

:?
Click to expand...

Had this problem in 80 rooms in a hotel that I was an apprentice on. We ended up installing GFCI blanks just for the lights. I guess they are rated differently?
 
WIMaster said:
It will if one absent mindedly wires a smartlock GFCI reverse polarity then turns the circuit back on. :ashamed1:
Click to expand...

Also if the polarity got reversed ahead of the GFCI in a junction box. That happens quite a bit with old cloth wiring. On much of that old stuff, the outside looks the same for both hot and neutral and gets mixed up in junction boxes all the time.
 
Thank you all for the input on the floro lights, that one has been bugging me for a while now. Inquiring(and sometimes strange) minds like to know.
 
JFletcher said:
Receptacles go bad quite a bit, .....
Click to expand...

J.P. said:
I have had enough that worked fine after replacing them that unless there is some obvious fault ( bad cord, ect..) I replace the GFI. 99% of the time that fixes it....
Click to expand...

K8MHZ said:
Top of the list, bad receptacles.
....
Click to expand...
Diagnosing bad GFCI recpts is pretty straight forward. They don't reset or they don't trip when they should. I have changed more than a few out that were a burnt up mess when I pulled them out of the box. Not much troubleshooting involved in those.
 
???

???

I may be missing the obvious, but I still don't see why reverse polarity will trip GFCI.

I can hook old 2/wire romex to GFCI receptacle and nothing to ground screw. If I have reverse polarity will it trip? If not, and I then add ground, will it now trip?
 
Status
Not open for further replies.
Top