I've got a box where

NMC comes in and hits a GFCI GFCI feeds both one NMC going out (shop outlets) and a smart switch. Smart switch feeds NMC going out (exterior outlet). Everything is correctly sized for 20A.

Since both the GFCI and the smart switch need neutral, this means five neutrals have to be connected to each other. I believe the switch neutral is currently daisy-chained past the GFCI neutral (I know hot is) bit that's still the three cables plus the pigtail having to come together in the box. That was successfully squozen into a single larger wire nut, and it all works, but I'm just a bit skeptical about whether that was really the right answer and will stay out that way.

What's the right way to handle this slightly complicated box, and what's the minimum box size for it? And are there any tricks to dressing down the wiring that would make it a bit less of a rat's nest? (Maybe subgrouping the neutrals?)

  • 2
    1 Pigtail from GFCI Load neutral terminal, 2 Shop Outlets, 3 Smart Switch, 4 Switched Stuff -- that's four neutrals. I don't count five neutrals. The neutral coming in to the GFCI goes directly to the Line neutral terminal. I would use a Wago 221-415 for the neutrals. It's easier to fold the neutral bundle into the box, and because you have a GFCI and smart switch that both will need maintenance, it's easier to remove and replace them without damaging the wires.
    – jay613
    Jun 30, 2023 at 15:43
  • 1
    @jay613 not to be all isherwood, but the answer box is below. Keshlam, boxes that are anywhere close to maximum fill, particularly with bulky items like GFCIs in them (counted no differently than a normal-sized receptacle) are just plain tight to work in. Feel free to oversize the box for your own sanity.
    – Ecnerwal
    Jun 30, 2023 at 17:35
  • Yes, those do sound like answers (and I'm often guilty of answer-in-comment myself). There's a deep mud ring which does gain a bit of space; never been sure if that counts or not. Sanity is good... I think I can see it from here...
    – keshlam
    Jun 30, 2023 at 17:50
  • 1
    Mud rings not only count, they are marked to tell you how much they count for.
    – Ecnerwal
    Jun 30, 2023 at 17:52
  • Ohhhhhh guys. I wanted confirmation of the 4 vs 5 neutrals, and I can't craft box fill answers (though I should probably start trying) so I kept it in comments for now.
    – jay613
    Jun 30, 2023 at 19:06

2 Answers 2


Codewise, unless you do a bad job and fail the "in a workmanlike manner" criteria, using one big wirenut or 2-3 smaller ones and a bunch of pigtails is the same. Pigtails within a box (as required if you want to spread out a connection to 2 or 3 wirenuts rather than one) are "free" for wire count / box fill purposes, though you can definitely make yourself miserable with how tight a box is that's just over minimum size by adding too many, or by mismanaging the wire paths into one big one.

If the GFCI has screw-and-clamp terminals that take two wires each, take advantage of that. That will cut the "wires per nut" by one.

First off, if I read your description correctly, the incoming hot and neutral just go straight to the Line terminals of the GFCI, no nuts or other junctions involved.

All the junctioning should be happening off the Load terminals, as you say the GFCI feeds it all. So the incoming cable does not see any junctions.

So, the GFCI Load terminals either have a pigtail that feeds outlets and switch, or a pigtail and one of the outlet neutrals if they are two-wire screw-and-clamp style. For the Load hots, all those have to feed is unswitched outlet and switch, so two-wire screw-and-clamp eliminates a wirenut completely on that side.

You have 6 wires, 2 devices (that count as 2 each), and 3 grounds (that count as 1) for wire count purposes. So, 11 is the magic number, and 24.75 cubic inches is your minimum box size. Not that I recommend skating anywhere near minimum box size if you don't absolutely have to. But in this case you have a box in place, so dealing with it being tight-but-legal is probably easier than upsizing it to comfortable-but-also-quite-generously-legal.

As noted in comments, a raised mud ring does add to the box's cubic inch count. Steel boxes are "standard" and not marked, (you just look up the number for the size of box) but raised covers and mud rings are marked with the cubic inches they add to the box they are attached to.


First, as the GFCI is about to explain by tripping... the GFCI "Load" terminals are special. They are so special that I regularly argue that novices should not use them. If the hot wire is coming off GFCI "Load", then its partner neutral wire must also come off GFCI "Load". So if you are using "Load", that will preclude one giant group of neutrals.

Also note that the GFCI is designed to take 2 wires under each screw - read the instructions for how - and this can help.

Now, as far as wire nuts, the manufacturer provides a list of all wire combinations for which UL has certified their wire nut, e.g. this one for Ideal. Though they also put a simpler chart in the sales brochure. I'm really good at wire nuts (most people aren't) and trust me - try to stay in the "center of range" because making wire nuts work at their limits is hard. Always do an earnest pull-test and learn from it. And crank it like you mean it. Or just use Wago lever-nuts.

  • I think it is actually correctly, since the tester popped the GFCI as expected. From both the switched and unstitched outlets. But sounds like I Really Should recheck this.
    – keshlam
    Jun 30, 2023 at 20:41
  • No experience with the wagos. Sounds like I should learn. But then what do I do with the bin of nuts? ... Don't answer that.
    – keshlam
    Jun 30, 2023 at 20:43

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