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I was replacing an outlet in my bathroom with a gfci outlet. When I throw on the power, it trips but not only that, it takes out a set of lights over the mirror which are connected to a double switch on the wall. The other switch is fine. What should I be looking for to fix this issue?

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  • Are you certain that you got the LINE & LOAD terminals on your new GFCI connected the right way around?
    – brhans
    Aug 14, 2018 at 16:35
  • Yes. That I am sure of.
    – dx3evan
    Aug 14, 2018 at 17:04
  • Why are you using the LOAD terminals on the GFCI? Aug 14, 2018 at 17:32
  • Why wouldn't you? It's not at the end of the line.
    – dx3evan
    Aug 14, 2018 at 18:45
  • You could have some bootleg grounds causing the problem or an older device that actually has some leakage causing the GFCI to trip. It only takes 5ma to cause a GFCI to trip.
    – Ed Beal
    Aug 14, 2018 at 18:50

2 Answers 2

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Because "continuing the circuit" is a completely different thing than "placing a load inside the GFCI's protected zone". Especially where switches are present!

I get it. You've installed receptacles for decades. You know (other than split receptacles) the extra 2 screws on the receptacle are for continuing the circuit onward.

Now you also know there are some receptacles (eg. USB) that only have 2 supply terminal screws. They do not provide any method for continuing the circuit onward. With those, you are forced to pigtail the receptacle and use a wirenut to splice its supply with the onward wires.

GFCIs are like that too, GFCIs only have two supply screws. They are conspicuously marked LINE and they are the only terminals not covered with warning tape. (The warning tape says, in so many words, "For Wizards Only".)So, similar to a USB, these should be pigtailed with a wirenut for continuing the circuit onward. Only the LINE terminals should be used. This is especially true in a retrofit situation like this, and double especially when there is a switch in the same box.

Everything I have said so far is about continuing a circuit onward, which is what you are trying to do. Now we're going to turn the page.


GFCi devices come in several packaging styles. There,s the GFCI+breaker, the plain GFCI deadfront, and our friend the GFCI+receptacle. All of them provide a "GFCI protected zone". Obviously, on a GFCI+receptacle, the protected zone is the built-in sockets.

However, all of them can extend their zone of protection beyond the device itself. (That'd be kinda necessary on the breaker and deadfront, eh!?) How to do that is beyond the scope of this answer. But you may know a rule that currents must be equal in any cable. That rule applies in spades to any GFCI zone of protection. This makes it rather tricky to work with them in switch boxes.

However there's generally no value or benefit to putting hardwired bathroom lights, fan, heater etc. on a GFCI.


Bottom line, pigtail everything to LINE and call it good.

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  • Thank you, I will try that. Thanks for all of the input and I'll update you soon.
    – dx3evan
    Aug 14, 2018 at 21:10
  • Harper, “for wizards only”? Can you point me to an expansion of this point? I’ve been adding receptacles and devices downstream from GFCI+receptacles from the LOAD terminals for years, and it seems simple - unless there is something I’m missing?
    – paul
    Aug 14, 2018 at 21:57
  • @paul -- you have to know that you can't do anything that causes current to bypass the GFCI when you do that, and that's something not everyone picks up on straight away...never mind the classic mistake of mixing up LINE and LOAD. Aug 14, 2018 at 22:22
  • Exactly @Paul, the issue is your loadside wiring must have equal currents by design. That should happen automatically if the two wires on the LOAD leave the box immediately in a /2 cable. So it's a non-issue there. A 3-gang bathroom 2switch+receptacle box, different deal. Bigtime. Aug 14, 2018 at 23:09
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I am afraid I have to respectfully but strongly disagree with the idea that removing the load from the GFCI protection is an acceptable solution. That's along the lines of putting black tape over the OIL light on your car's dash so you don't have to deal with the irritating red glow. It's better to at least try to figure out what's going on and see if there's a potential hazard.

There's a reason GFCI protection is required in bathrooms, it's a place where faults are more likely to be dangerous due to proximity to water and plumbing. GFCI's trip levels are tiny but so are the actual voltages that can harm a person. Even a mind jolt in the bathroom can be dangerous - even if the zap doesn't do much damage, the fall might.

I'd first test the receptacle itself. Temporarily remove the load wires and cap them, and see if the GFCI will hold with no load. If it holds, plug in a load - something simple like a lamp - see if it holds. If it holds, see if it trips as it should with a GFCI receptacle tester. (If you have solenoid voltage tester, you can also test a GFCI by testing voltage from hot to ground - the load of the solenoid should trip the GFCI.)

At that point I'd replace the load wires and see if the GFCI still trips. If so, disconnect and cap off the downstream loads one by one. If you determine one of the loads is leaking voltage, you can decide whether to replace it or run it without GFCI protection.

If it trips with all the loads disconnected, that points to a wiring fault, which is bad news - it may be difficult to track down - but it is potentially dangerous, and should be corrected.

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  • The problem with GFCI protecting lighting in a bathroom is that a faulty appliance can proceed to take your lights out, leaving you in the dark, and ground faults in lighting (even in a bathroom) are far rarer and less hazardous than ground faults in a bathroom appliance, as you're far more likely to be in contact with the latter Aug 14, 2018 at 22:23
  • The problem is this is not an answer to the question. OP's light was never on GFCI and he didn't expect or want it to be. He has a very specific problem that happens with bathroom switches next to receptacles when those are upgraded to GFCI. You don't fully understand the problem, so your advice is generalized, armwavey and not all that helpful. Trust me if you grasped his problem, you'd be telling him the same Aug 14, 2018 at 22:43
  • WOW @harper condescend much? Try to keep it respectful. My answer is an answer; I understand GFCI quite well. I doubt it's simple proximity to the switch. The safest thing would be to test further. Aug 14, 2018 at 23:28
  • @ThreePhaseEel - I agree that leaving the occupant in the cark is an issue and that lighting is less dangerous since there's less contact with the housing etc. However if there is a fault in the wiring feeding the light, it may cause a touch potential on something people DO come in contact with. Aug 14, 2018 at 23:32
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    Fight nice please. :0) I was able to fix the issue. There was a switched neutral wire. It's an old box and there isn't a lot of room to play. I thought I was careful to follow the wires but because they are crammed so tight and don't pull out very far, they were switched. All 4 wires are properly placed in their appropriate spots. I now have a GFCI on my outlet and my switches work just fine. Thank you all for taking the time to give your thoughts. It's always good to have a second (third, forth & fifth) opinion to make sure things are done right, especially when you're not an electrician!
    – dx3evan
    Aug 15, 2018 at 1:13

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