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I want to wire a new exterior front of house gfci WR outlet, from an existing garage gfci. I would like this new exterior outlet to be on a switch, so I'm thinking the wiring will be

Source -> garage GFCI -> switch -> exterior GFCI.

My question is basically how to do the specifics, and do I need pig tails anywhere. I'm thinking:

black/hot: source to LINE on garage gfci, LOAD from garage gfci to switch, 2nd switch terminal to LINE on exterior gfci

white/neutral: source to LINE on garage gfci, LOAD from garage gfci to LINE on exterior gfci

All switches, boxes, and outlets will be grounded via ground wire and metal boxes.

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    Why are you wanting to use a GFCI on the LOAD side of another GFCI? – ThreePhaseEel May 12 at 2:09
  • Because code requires exterior (and garage) outlets to be gfci. Also, the one I have is rated Weather Resistant. – dabi May 12 at 2:42
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    the garage GFCI outlet's LOAD terminals are protected by the GFCI just as well as the receptacles on the front are! – ThreePhaseEel May 12 at 2:43
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    GFCI protected means exactly that, "Protected by a GFCI" One GFCI as the first outlet on each garage outlet circuit will protect all the other outlets that are fed from its load terminals, and every one of those can be a normal outlet. Or you can use a GFCI breaker and none of the outlets need to be GFCI outlets. Chaining GFCIs is madness, as any one of them could be the "first to trip" in the event of a fault, so it's VERY hard to track down the affected one. Not to mention the amount of cash you'll burn .vs. using normal outlets on the load terminals of one per circuit... – Ecnerwal May 12 at 3:35
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    No, Code does not require that. Code requires outlets to be protected by a GFCI device of some kind. It does not need to be a "GFCI+receptacle combo device" which is what you call a GFCI, and it does not need to be in that location. Protecting downstream plain-outlets is the solitary purpose of the LOAD connections; if you don't wish to use that feature, then your installation will be more reliable if you don't use LOAD at all. – Harper May 12 at 4:09
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Your plan is correct except the outside GFCI should be replaced with a plain outlet, since it will be under the protection of the first GFCI. It needs a "GFCI protected" label to be applied 5 minutes before any inspection.

Generally you should go one of two ways with GFCIs:

  • Use a GFCI device of any kind in the first location to be protected, and then feed the rest of the circuit downline off of that GFCI devices's LOAD terminals. If you want to make the wiring simple, use a GFCI+breaker instead of a GFCI+receptacle. However, this will reveal any flaw in your wiring, including wiring around a switch.

  • Use a GFCI+receptacle specifically, in each and every socket location you aim to protect, and do not use the LOAD terminals at all. In fact, the LOAD terminals come with warning tape that says (in as many words) "For Wizards Only - Do Not Remove"; when you wire with this method, you are following the "I am not a wizard" rules.

Most GFCIs let you put two wires on the LINE screws, or you can pigtail.

While the second technique may seem like a waste of money (which it is), it has its applications. One of them is when you want to un-protect a receptacle at the end of the chain. Another is when the downline circuit has a difficult-to-troubleshoot problem, or when it is a shared-neutral circuit.

There are three things you should not do. First, you should not feed a GFCI from the LOAD terminals of another GFCI -- that is simply playing a "Yo Dawg" joke on yourself, and wasting money.

Second, try to avoid putting a GFCI device past a switch. Some of them do not like having power severed, and will nuisance-trip.

Third, try to avoid putting GFCI devices outdoors. They say they are outdoor rated, but it doesn't really work (partly because outdoor "in-use" boxes don't really work).

  • Please clarify "However, this will reveal any flaw in your wiring". Do I understand correctly that a GFCI protected plain outlet is not equal to a GFCI device? Thus there is no issue putting a GFCI protected plain outlet past a switch, nor using one outdoors. If in-use boxes "don't really work" is there a better option? – dabi May 12 at 18:06
  • @dabi it is more than equal; it is actually better to have a GFCI protected plain outlet, because the wires are also protected. The issue is that if you are relying on onward wiring in the walls that is already built, it might contain certain already-existing wiring defects that would trip a GFCI. That would necessitate finding and repairing the defect right away. It should be fixed regardless, but the GFCI will really keep you honest :) – Harper May 12 at 18:43
  • Well, in-use boxes are government-mandated, need I say more. I prefer to put a little "birdhouse, with a door" over top of any outdoor electrical, simply to keep the rain off of it. The house should have a door notch seal or gasket of some kind, and an open bottom (for the cords :) This won't eliminate condensation, but rain/snow is 90% of it. – Harper May 12 at 18:45
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What you propose will work (assuming you’re also connecting grounds). However, you have no reason to use a GFCI outlet on the load side of the first. In fact, you don’t want to use one. Outdoor GFCI outlet don’t last, even with a an outdoor cover.

If you get a ground fault outside, there is no guarantee that the outdoor GFCI will trip first.

Just use a good quality normal outlet downstream of the switch and garage GFCI. Don’t forget to label that outlet “GFCI protected”.

Edit: as Harper noted in his answer, if you really want the GFCI Outside (so you can reset it there, for example), don’t put it downstream of the inside GFCI. Instead of connecting to the LOAD terminals, instead connect to the wires feeding the LINE side. You’ll probably need to use wirenuts to add pigtails (short wires) to connect the indoor outlet.

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