View Full Version : GFCI Trips when Light Switch is Turned Off

07-24-2008, 04:51 AM
Good Morning!

I'm into the finishing stages of my bathroom remodel and am having an "issue" with the GFCI outlet.

I have a double gang box that houses a GFCI outlet and a double light switch. The power comes into the box and it split with one leg going to the GFCI and the other feeding the double light switch. Nothing is wired to the load side of the GFCI.

Sometimes when you turn off one of the switches the GFCI will trip. I noticed this Monday and replaced both the switch and the GFCI with new units. I thought I was in the clear, but the situation repeated itself this morning.

I know that there is going to be arcing in the switch and am assuming that the GFCI is detecting this.

Is there anything I can do to eliminate this situation?

This is wired exactly the same way it was before and I didn't experience this problem (at least I can't recall).

Thanks in advance for any and all help!


07-24-2008, 09:41 AM
Thanks for your input! They are on the same breaker so the neutrals are tied together.

What is the best way to rectify the problem at this point?

I had to do a bunch of rewiring for the kitchen and bathroom remodel.

Essentially a circuit come up from the basement and feeds (1) outlet in the dining room. This travels up to the attic where it feeds (2) outlets in my office, (1) outlet in the hall and the GFCI and fan/light combo in the bathroom.

In the attic I installed (3) junction boxes to allow me to isolate the bathroom on it's own circuit during the next phase of the remodel. Even with that done, the GFCI and fan/light combo will still be on the same circuit thus sharing the same neutral.

Thanks again!


Ian Gills
07-24-2008, 09:44 AM
I deleted my post because I was having trouble visualizing this. These GFCIs can be tricky!

If it is all on one circuit, I would install a GFCI breaker and be done with it. Just an idea. Although as a remodel the bathroom really should be on its own circuit. I gather you will be doing this next?

07-24-2008, 09:45 AM
That was confusing! I saw your post then it disappeared!

I can draw up a quick sketch if that would help.

Ian Gills
07-24-2008, 09:50 AM
We need a pro becaue I am just guessing here.

07-24-2008, 10:08 AM
Sounds great!

I'm looking forward to any replies.


07-24-2008, 10:16 AM
Try wiring the lights to the load side of the gfci. Also, make sure that if the gfci has pigtails verses screws for connection that the load side leads are capped and can't touch anything.

Was anything plugged into the gfci at the time? If so, remove it and see what happens.

The GFCI is comparing the hot and neutral current, and if they differ it would trip. My guess is that it shouldn't care about a load on the line side, only its internal outlets and the load side.

07-24-2008, 10:28 AM
The GFCI has screws for attachements and they are taped up to prevent inadverent contact with anything. I had a fan plugged in at the time, but I'm pretty sure it did it w/o anything plugged in as well. I will check that when I get home.

Would running the fans / light from the load side make the GFCI trip all the time since it is now?

I completetly forgot about this ...

There was an uncapped hot wire in the box when I installed the GFCI that I inadvertently tied in in the attic. I had 12-3 with ground and used that as opposed to buying more cable and the red wire accidently got tied in.

When I was securing the GFCI, the red wire shorted out against the metal box and blew the breaker. I found out what the problem was and disconnected the offending wire in the attic. Even though the breaker blew could the GFCI have been effected someway?

Thanks again!

07-24-2008, 11:17 AM
The gfci could be toast. Make sure self-test works, and sometimes an external plug-in tester is more complete (don't know that for sure).

07-24-2008, 11:58 AM
I have used an external GFCI tester and it operates properly. That being said, I picked up another double switch and GFCI to swap them out and give that a try.

Other than that I can't come up with a reason why the GFCI would trip. Like I said I pigtailed the hot and the neutral with one leg of the pigtail supplying power to the GFCI and the other to the pair of switches.

The GFCI doesn't trip if nothing is plugged into it. With a device plugged into it and not running, it does trip when the light switch is toggled.

Always something.

07-25-2008, 09:25 PM
Is there a lighted switch? Also make SURE that the ground is properly isolated throughout the house.

One other posibility is the GFI is sensing the inductance from the fan motor as an impalance. Try pluging just a lamp into the fan/heater outlets in the celing fan enclosure.

07-25-2008, 09:30 PM
One other posibility is the GFI is sensing the inductance from the fan motor as an imbalance.

This simply does not happen...

07-26-2008, 07:59 AM
I just swapped out the GFCI with another. It works like a champ.

I can only assume that when the hot wire shorted to the box it messed up the GFCI.