Intermittent gfi tripping

Jason H

Member
Location
Colorado
Occupation
Journeyman
I am at my wits end with this dwelling garage gfci circuit. My first visit I re-did the existing make up in all openings and was sure I found the issue, being the ground having close contact with the screw terminal, tested the circuit after and made sure it was holding with a load.. Now 2 months later they say it tripped again. Any thoughts?
 

kwired

Electron manager
Location
NE Nebraska
Unattended loads being supplied like maybe a refrigerator/freezer? Sometimes inductive kickback when they switch off can trip some GFCI's, will be somewhat random when they do this.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Seems like a good place to once again warn against using surge suppressors (outlet strips, devices with internal SPD, etc.) plugged into a GFCI receptacle or into receptacles on a GFCI protected circuit. Don't know if that's your situation, but doing so will cause exactly the problem you have.

-Hal
 

jmellc

Senior Member
Location
Durham, NC
Occupation
Facility Maintenance Tech. Licensed Electrician
I used to see a lot trip from refrigerators & freezers. They would trip the receptacles but not the breakers. I replaced some with GFCI breakers. Earlier on, I would use the dedicated space exception to put a standard circuit in for the appliance.
 

Jason H

Member
Location
Colorado
Occupation
Journeyman
A GFCI will trip with a neutral to ground connection.
What are the loads on the GFCI and which of them are always on?
Nothing is permanent except the garage door openers as far as load. My first visit her christmas lights were tripping the gfci but only as you unplugged the lights from the outlet. If I plugged them back in and reset the gfci the load would hold which is why I determined it was bad make up having close contact with the bare ground
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Nothing is permanent except the garage door openers as far as load.
Very possible that the door openers have internal surge protection. Figure out a way to disconnect them and temporarily supply them from a different circuit. With nothing on the GFCI circuit see if it still trips.

-Hal
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
I am at my wits end with this dwelling garage gfci circuit. My first visit I re-did the existing make up in all openings and was sure I found the issue, being the ground having close contact with the screw terminal, tested the circuit after and made sure it was holding with a load.. Now 2 months later they say it tripped again. Any thoughts?
First off, is it a GFCI receptacle or GFCI breaker?
Then "two months later they say it tripped again", do you know what they were using or plugged in?
It could have tripped off from a storm or something plugged in that had a fault. I would take "tripped again" with a grain of salt until I could witness it tripping!
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
My first visit her christmas lights were tripping the gfci but only as you unplugged the lights from the outlet. If I plugged them back in and reset the gfci the load would hold which is why I determined it was bad make up having close contact with the bare ground
I assume you assumed that the bare ground was contacting the neutral screw on the receptacle because the receptacle moved when the plug was removed?

First off, is it a GFCI receptacle or GFCI breaker?
I'm assuming a GFCI breaker.

It could have tripped off from a storm or something plugged in that had a fault. I would take "tripped again" with a grain of salt until I could witness it tripping!
Absolutely! NEVER take the word of a customer. If you didn't see it happen it didn't happen.


-Hal
 

bzzt

Member
Location
mn
Occupation
wirer
Nothing is permanent except the garage door openers as far as load. My first visit her christmas lights were tripping the gfci but only as you unplugged the lights from the outlet. If I plugged them back in and reset the gfci the load would hold which is why I determined it was bad make up having close contact with the bare ground
If you found 1 with poor makeup probably another with the same. I'd start in the middle of the circuit and either megger or check continuity with everything unplugged. Moisture in an exterior box maybe? exterior lights often get crammed into boxes with little care
 

Flicker Index

Senior Member
Location
Pac NW
Occupation
Lights
Depending on when the GFCI was made, replacing it with a new model, perhaps from a different brand may help. GFCI doesn't stop ground fault current from flowing. It has a current transformer with all current carrying conductors going through it. When all current flow goes through the wrapped wires, they cancel out and produces no output on the CT. Whether it shuts off in half a cycle or three cycles have no meaningful effect on safety purpose of the device but having a DSP that can ignore spikes caused by inductive kickbacks dramatically reduces nuisance trips and DSP algorithm on a new GFCI could very well be better than something that was installed back when they were first code mandated. They're cheap enough that replacing it is worthwhile if the existing GFCI is rather ancient.

The stored energy in coil can cause a spike. The same energy that causes popping sound in sound system when you shut off a motor can is what sometimes causes false trips. That current pulse will still happen, but a good DSP can ignore it.
 

ptonsparky

Senior Member
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
Electrical Contractor
I’ve had good luck with adding small suppressors, designed to handle that coil spike, to residential GFCI and LEDs that blinked as a fan speed control , IIRC, was cycled. They were not always on the same branch circuit.

Only problem I’ve seen so far is they are Recognized, not Listed.
 

Jason H

Member
Location
Colorado
Occupation
Journeyman
First off, is it a GFCI receptacle or GFCI breaker?
Then "two months later they say it tripped again", do you know what they were using or plugged in?
It could have tripped off from a storm or something plugged in that had a fault. I would take "tripped again" with a grain of salt until I could witness it tripping!
Receptacle.. apparently it happens when they have their diesel truck plugged in, however, they have been using a different exterior gfi circuit since the last trip and it works fine on that circuit.
 

kwired

Electron manager
Location
NE Nebraska
Receptacle.. apparently it happens when they have their diesel truck plugged in, however, they have been using a different exterior gfi circuit since the last trip and it works fine on that circuit.
Nearly every time I get called for engine heaters tripping GFCI's the engine heater, the supply cord or even any extension cord being used ends up having ground fault conditions. Can be intermittent depending on amount of moisture presence at times.

People see this as inconvenience and want you to eliminate the GFCI. You need to prove there is something wrong and convince them this tripping device it is protecting them from potentially walking up to that vehicle someday and being electrocuted when they touch it.
 

kwired

Electron manager
Location
NE Nebraska
Try telling that to my 82 year old farmer who’s tractor won’t start. He broke the shutters out of one of the TRGFCI. Strings an extra 100’ feet of cord to the grain bins to avoid them Damn things.
I know those types as well.

Also seen cases where they appeared to be avoiding plugging into GFCI receptacles, even though the other receptacles that they did plug into were GFCI protected anyway.
 

hbiss

EC, Westchester, New York NEC: 2014
Location
Hawthorne, New York NEC: 2014
Occupation
EC
Nearly every time I get called for engine heaters tripping GFCI's the engine heater, the supply cord or even any extension cord being used ends up having ground fault conditions. Can be intermittent depending on amount of moisture presence at times.
Interestingly, the OP said the first time he was there was because the Christmas lights were tripping the GFCI.

-Hal
 
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