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I was replacing a GFCI, and noticed 7 total wires:

2 load wires

4 line wires

1 ground

It is my understanding that the line wires are the power source coming to the GFCI, and the load wires are providing power to the next receptacle (or switch, etc).

Does anyone know why there is 4 line wires? The instructions on the new GFCI explicitly stated not to use if more than 4 total wires (e.g., 2 line, 2 load) not including the ground.

Do I replace with the new GFCI exactly as found? Or does this pose some type of hazard?line wires

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    The white wires are neutral wires. NOT line or load. I see 3 black wires. What is the problem you need to address here ?
    – Alaska Man
    Jan 29, 2020 at 19:17
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    @AlaskaMan, that's not quite right -- with a GFCI, the line/load concept applies to both the hot and neutral wires, and if the line/load neutrals are not kept separate, the GFCI will trip immediately.
    – Nate S.
    Jan 29, 2020 at 19:19
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    @NateS. thanks but there is still only 3 "hot" wires. NO?
    – Alaska Man
    Jan 29, 2020 at 19:21
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    Does this answer your question? Can I wire a GFCI outlet with 3 hots and 3 neutrals? Current answers do not mention the real reason you can only have "4 wires", but that question does.
    – JPhi1618
    Jan 29, 2020 at 19:27
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    As with all such questions, it's worth asking why are you replacing the GFCI? Because you don't like the colour? Does it not trip when you use the TEST button? Or is it that it is not resetting? If the latter, don't expect that it will fix your problem.
    – J...
    Jan 30, 2020 at 17:38

5 Answers 5

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The additional connection holes at the line terminals are provided to extend an unprotected circuit to a location that doesn't need GFCI protection or to a location that GFCI protection will be individually provided.

I don't know what the installation instruction included with your receptacle says, but step 6 in the Leviton Installation Instructions doesn't actually prohibit installation with more than 4 wires, but instructs to have a qualified electrician do the installation. This is probably an overly cautious step to make sure somebody doesn't inadvertently connect wires to the hot terminals that were previously connected to the load that serves a location where GFCI protection is required. It could also be remotely possibly addressing cubic inch fill limitations in NEC 314, but there is little evidence of that.

Replacing wire for wire should work if it was previously working properly, but I am cautious to recommend that since nobody over the internet can completely determine that no areas being served by the unprotected hot are in areas that now require GFCI protection.

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    I think the wire fill is more important than you think. 6+ wires and a GFCI receptacle are too much for all but the largest single gang box.
    – JPhi1618
    Jan 30, 2020 at 16:36
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    "The additional connection holes at the line terminals are provided " - okay, but why are there two sets of additional holes? Is it so that you can extend the circuit to two places?
    – user253751
    Jan 30, 2020 at 16:38
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    @JPhil1618 I wasn't implying it wasn't important, only that box fill didn't seem to be addressed in the documentation I was looking at.
    – NoSparksPlease
    Jan 30, 2020 at 17:57
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    @user253751 The receptacle appears to be clamp type that you can't attach directly to the screws, holes are the only option. So the two sets of holes on the line is for one feed from the panel, and one set to additional loads unprotected.
    – NoSparksPlease
    Jan 30, 2020 at 18:01
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First, test the GFCI properly

I am always cautious when people replace GFCIs. GFCIs are very poorly understood, and I find 90% of the time they are "throwing parts at a problem". This is a waste of money, and invites mistakes.

So let's make the relevant test. Remove the wires from the LOAD terminals. (you have to loosen the screws to do that; these are screw-and-clamp. Then cap off the wires.

Test the GFCI now. Does it clear? I bet it does.

So now you need to search for which outlets and loads have lost power. One of them has a problem, specifically a ground fault, You'll need to reattach the LOAD wires, then eliminate loads one at a time until the problem clears. If removing all loads doesn't clear the problem, then it's in the wiring.

It's unlikely to be the GFCI.

What is LOAD?

It is my understanding that the line wires are the power source coming to the GFCI, and the load wires are providing power to the next receptacle (or switch, etc).

No. That's not what LOAD means at all. What you're referring to is "onward power" and just gets a plain splice.

LOAD means "the downline devices subject to control from this device". GFCI is a ... well, you don't know what it is. When you fully understand GFCI, you can can put it to use. That will come in time, but recognize it isn't now.

In the meantime, don't use it. Or in this case, don't tamper with it.

Leave it exactly the way you found it.

Does anyone know why there is 4 line wires? The instructions on the new GFCI explicitly stated not to use if more than 4 total wires (e.g., 2 line, 2 load) not including the ground.

What that is saying is that >4 wires is beyond the scope of the DIY instructions. What's the story there? Your GFCI device has a UL listing. A UL listing doesn't just approve the device bare, but the device, labeling and instructions as a matched set. (that's why instructions can seem so dated and horrible; companies are reluctant to update them because they don't want to mess with their UL listing).

Instructions to include various 6-wire iterations would be much more complicated, and involve more haggling and uncertainty about the UL listing being approved. So "Ask your electrician" was the easy way to do it.

For you, it's simple enough. If you have 2 wires that definitely land on the same terminal and are definitely connected, those can be replaced with a pigtail. Doing so with the LINE wires reduces your wire count to 4, and makes the instructions followable.

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  • The old method of letting a device like a receptacle bridge "upstream" and "downstream" wires on the same circuit (LINE in this context) has fallen out of favor. Pigtails are better.
    – Monty Harder
    Jan 30, 2020 at 17:05
  • @MontyHarder I don't know about NEC, but Canadian regulations actually require that at least the neutrals are pigtailed together and then to the device. This greatly reduces the risk of accidentally leaving an open neutral in the case of removing the device from the box.
    – J...
    Jan 30, 2020 at 17:36
  • @J... In the States, that's only true for MWBCs. Receptacles are dual-mode - don't break the tab and you splice 2 wires (4 with screw-and-clamp), do break the tab and get separate control. I am a huge fan of the pigtailing method, but then, I'm also a huge fan of stranded wire, and getting that correct on a screw is best done at the bench, not on a ladder.
    – Harper - Reinstate Monica
    Jan 30, 2020 at 18:49
  • @Harper-ReinstateMonica Yeah, we have the same receptacles, it's just not allowed to use them as a splice, at least for the neutrals.
    – J...
    Jan 30, 2020 at 18:51
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The load connections are GFCI protected. So anything hanging off of the load connections are protected also.

The line connections are not GFCI protected. There are 2 sets of wires because you (someone) is just using the GFCI outlet as a tie point to provide un-proteced power down stream to another outlet, switch, light, etc.

See this: https://www.thespruce.com/line-or-load-gfci-connection-1152785

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The 4 wires you speak of are usually spliced together with tails to the line side of gfi. They represent incoming and outgoing part of branch circuit. The load side represents the additional outlet or lights protected by the branch circuit.

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  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here.
    – Daniel Griscom
    Feb 1, 2020 at 1:13
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The white line wires are your incoming neutral. The right black wires are your incoming hot. The bare copper is your ground. The load white wire is your load neutral and the black load wire is your black load hot. The load side of the Gfci protects outlets downstream of the device with GFCI protection. The reason you have 2 white and 2 blacks on your line (top) is they are backstabbed which is a quick/lower class way of splicing in and out of your outlet. It’s also not NEC to use the device as a splice.

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  • Can you give me a citation about the NEC prohibiting the use of wiring devices as splice points generically? (The only cases I know of that forbid it are EGCs and MWBC neutrals....)
    – ThreePhaseEel
    Jan 31, 2020 at 12:45

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