GFCI Tripping (When Load is switched OFF)?

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busman

busman

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Location
Northern Virginia
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Master Electrician / Electrical Engineer
Got a customer who swears the GFCI breaker trips when she shuts off items in the bathroom. Mostly the Fluorescent Light, sometimes the hair dryer, but always when she shuts it off. Any ideas? I was thinking maybe the inductance of the motor/ballast could be causing an arc to ground somewhere. Kinda like when you open the points on a car ignition coil, it causes a momentary spark on the spark plug.

I had planned to:

Check the load on the breaker
Replace the breaker with a non-GFCI unit
Put a temp GFCI on the circuit.

Any other ideas? I haven't come across this situation before.

Thanks,

Mark
 
I infer that this is a bathroom served by a single circuit that serves nothing outside that bathroom. Otherwise, you couldn't have both a light fixture and a receptacle outlet in a bathroom on the same circuit. But I would take a moment to verify that (i.e., does anything outside the bathroom lose power?).

Next, it is usually best to begin with the presumption that if a GFCI is tripping, then it is correctly doing its job, and that some component has a leakage current to ground. In this case, however, with the symptom only occuring as items are turned off, especially since it happens with different items, then the circuit itself becomes suspect.

I would suggest replacing the breaker with a non-gfci, and replacing the receptacle(s) with GFCI, and see if the symptom disappears.
 
I have a circuit in my basement that does the exact same thing. I think it might be from capacitive coupling to ground. Something causes an inductive kick when its turned off, and the kick causes a brief pulse of current to ground.

I would try a new GFI breaker. I would also make sure there isn't too much wiring length on the breaker.

BTW, I also have GFCI receptacles that trip when there is a thunderstorm. Maybe its because I buy the cheapest GFCI receptacles I can find.

Steve
 
1. Replace the GFCI breaker, even if temporarily, as an experiment.

2. Replace the GFCI breaker with a standard one, and install a GFCI receptacle.


Hint: #2 is usually cheaper, and removes the light from the equation.
 
LarryFine said:
1. Replace the GFCI breaker, even if temporarily, as an experiment.

2. Replace the GFCI breaker with a standard one, and install a GFCI receptacle.


Hint: #2 is usually cheaper, and removes the light from the equation.
Click to expand...


Yeah, #2 is my plan. Just wondered if any of you had seen this before?

Thanks,

Mark
 
I have this issue in my house...a 2 tube 40W T12 fixture with a magnetic ballast sometimes trips the GFCI when it is shut off. In fact it happed today, but it only happens once in a while (maybe once of twice a year). It has been doing this ever since it was first installed, about 25 years ago. I think that there some kind of a kick that happens if you turn the light off at exactly the correct point on the sine wave.
 
I have seen this as far back as I can remember, back when we use to put the master bath on with the master bedroom, the paddle fan would do it if it had a duo dehummer type control, hair driers, vacuum cleaners. but newer breakers are supposed to be immune to this (yea right) just try one of those cheepo manerds GFCI receptacles in the red boxes, they will trip on just about anything. we use leviton and haven't had a problem since
 
steve66 said:
I have a circuit in my basement that does the exact same thing. I think it might be from capacitive coupling to ground. Something causes an inductive kick when its turned off, and the kick causes a brief pulse of current to ground.

I would try a new GFI breaker. I would also make sure there isn't too much wiring length on the breaker.

BTW, I also have GFCI receptacles that trip when there is a thunderstorm. Maybe its because I buy the cheapest GFCI receptacles I can find.

Steve
Click to expand...

Yea, and mine just happens to have a small freezer plugged into it. Wife raised HH when she went to dish up her favorite ice cream and it had melted for the second time in two weeks. New house with a new GFCI. Someday I better get around to changing it out.
 
GFCI single BC to bathroom

GFCI single BC to bathroom

busman said:
Yeah, #2 is my plan. Just wondered if any of you had seen this before?

Thanks,

Mark
Click to expand...

Hi Mark,

Larry is the go-to-guy on his #2 suggestion. (change out the panel GFCI to a standard breaker) Please note, this has been a frequent tripping problem on GFCI downstream fed bathroom equipment and in some cases, separate older bathroom GFCI only circuits.(1970's)

Additionally, make sure the standard breaker BC only parallels the GFCI receptacle in the bathroom on the retrofit. This way the bathroom lighting (fluorescent lamped) and vent fans etc... do not 'kick back' to trip the GFCI receptacle. If the new panel breaker trips, then the entire circuit needs troubleshooting. rbj
 
#2 Same resolution

#2 Same resolution

don_resqcapt19 said:
I have this issue in my house...a 2 tube 40W T12 fixture with a magnetic ballast sometimes trips the GFCI when it is shut off. In fact it happed today, but it only happens once in a while (maybe once of twice a year). It has been doing this ever since it was first installed, about 25 years ago. I think that there some kind of a kick that happens if you turn the light off at exactly the correct point on the sine wave.
Click to expand...

Hi Don,

Easy fix... parallel the GFCI receptacle in the bathroom. (15A Zinsco's were famous trippers)
 
busman said:
Got a customer who swears the GFCI breaker trips when she shuts off items in the bathroom. Mostly the Fluorescent Light, sometimes the hair dryer, but always when she shuts it off. Any ideas? I was thinking maybe the inductance of the motor/ballast could be causing an arc to ground somewhere. Kinda like when you open the points on a car ignition coil, it causes a momentary spark on the spark plug.

...
Any other ideas? I haven't come across this situation before.
Click to expand...

Did you check that the switch is any good, maybe it's just worn out! Maybe you need to put in a new one maybe a motor rated one since they are using all those mini-motors, just a though!
 
Credit due

Credit due

charlie b said:
I infer that this is a bathroom served by a single circuit that serves nothing outside that bathroom. Otherwise, you couldn't have both a light fixture and a receptacle outlet in a bathroom on the same circuit. But I would take a moment to verify that (i.e., does anything outside the bathroom lose power?).

Next, it is usually best to begin with the presumption that if a GFCI is tripping, then it is correctly doing its job, and that some component has a leakage current to ground. In this case, however, with the symptom only occuring as items are turned off, especially since it happens with different items, then the circuit itself becomes suspect.

I would suggest replacing the breaker with a non-gfci, and replacing the receptacle(s) with GFCI, and see if the symptom disappears.
Click to expand...

Sorry Charlie,
I read past your last sentence but read Larry's same comment. I believe both of you are right on top of the GFCI receptacle retrofit. rbj
 
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