HAD A customer that had a gfci fire in bath. They had a elect toothbrush charger pluged into one of the rec. The owner got up in night to use bathroom and saw sparks coming from gfci. He reached and unplugged the charger, and had a large arc that burned the wall and melted the gfci. He told me it tripped 2 breakers in panel. After looking into things, i discovered there were 2 circuits hooked up to the gfci. The circuits were on opposite sides of the bus, so he had 240v between the two at the gfci. Ive never run across this before so im wondering what happens when you hook up 2 circuits to a gfci. I ran A new dedicated 20 amp circuit to the bath to fix problem, but im wondering if i should be looking elsewhere for a more serious problem. I know in older homes they ran 2 circuits to the kit area on a 3 wire and removed tab on recep. to seperate circuits, but how would this work on a gfci?
GFCI FIRE
- Thread starter yelwdog
- Start date
- Status
dhalleron
Senior Member
- Location
- Louisville, KY
I'm not sure how you could hook up 2 circuits to a GFCI outlet. They don't have a tab to break off like a standard receptacle does. Internally both top and bottom outlets should be connected to the Line terminal I would think.
Mike Scarry
Member
- Location
- Roanoke, Virginia
An open neutral on a multi wire circuit can cause 240V to appear at normally 120V outlets in some circumstances.
ptonsparky
Tom
- Occupation
- EC - retired
Having a real hard time picturing the two circuits hooked to a GFCI, with both energized, and having it work even for a short periond of time. I may have to waste one and try it in my shop next time we have a slow day. I'll make sure the fire extinguisher is close.
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
Be sure to take video! I am sure there will be quite a show.
but really do you need to do this to actually know the outcome. It's like walking up to a 16' aligator and trying to pet it. We all know the outcome and don't really need to test it.
hmy:
kwired
Electron manager
- Location
- NE Nebraska
Tying the two conductors together with a wire nut should give the same test results - instant breaker trip.
Most likely the OP had a receptacle that was part of a MWBC, and not directly connected to both sides of the 240 volts. He also likely experienced a failure of the neutral someplace and more than 120 was imposed across the GFCI in question as a result.
Most likely the OP had a receptacle that was part of a MWBC, and not directly connected to both sides of the 240 volts. He also likely experienced a failure of the neutral someplace and more than 120 was imposed across the GFCI in question as a result.
ptonsparky
Tom
- Occupation
- EC - retired
Dang. I was hoping to see some smoke. Haven't seen any since...well last week:ashamed1:
kwired
Electron manager
- Location
- NE Nebraska
Omit the connection to neutral and connect the GFCI L1-L2 and you may get to see smoke.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
If the circuits were on opposite sides of the bus , then that would not guarantee 240V. My bet it was a loop circuit on the same phase.
ceb58
Senior Member
- Location
- Raeford, NC
If they were on opposite sides of the buss they would be the same phase and would only be 120v but if both had 20 amp breakers then in reality the gfci was on a 40 amp circuit.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
I'm having a hard time picturing the wiring on the GFCI receptacle. I can only assume both hots were on the line side. I don't think the recep. would even work if you had 1 circuit on the line side and the other on the load side. As already mentioned, it had to be part of a MWBC but why would both circuits be on 1 GFCI?:?
OP, can you describe the wiring to the GFCI better?
OP, can you describe the wiring to the GFCI better?
kwired
Electron manager
- Location
- NE Nebraska
If you have GFCI wired one line to input and one line to output everything may seem fine to the user as long as they don't try to reset the GFCI. Newer devices that detect miswiring may be different, but older ones will still allow plugged in devices to work when feed is terminated on the load terminals. There is no GFCI protection however.
kwired
Electron manager
- Location
- NE Nebraska
Like I said before it was probably tripped or malfunctioning and was backfed thru load terminals so it appeared to working to the owners.
This may have been split outlet at some time and someone not knowing any better, yet knew that it needed to be GFCI tried to replace it at some time. I have seen this happen before in a kitchen.
- Status