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I'm looking to upgrade my light switches to smart switches, which I've been doing mostly successfully around my house. However there are a number of large 4-gang switch boxes and I'm not sure what to do about the many wires which are brought together in a wire nut. In one switch there are 5 NM power lines coming in, and the neutrals are brought together. But there are 5 wires, isn't the maximum for a red wire nut 4 wires at 12 gauge?

Do I need to daisy chain together a couple of wire nuts in order to bring these wires together safely?

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  • Can you get bigger wire nuts?
    – ThreePhaseEel
    Commented Jul 15, 2020 at 20:18
  • You can go to larger wire nuts but then they are hard to fit in the box. I recommend splitting up the bundles that there is a smaller bundle of wires and you can bend the smaller bundles much easier . However I use red and tan scotch locks and I think they can handle 5 #14 wires and are not two bulky but with number 12 4-5 wires gets tough to bend and you have to go to blue/ gray I always check when I get close sometimes use crimps with snap on insulators I think those are stakon brand but not forgiving of mistakes. Are these all on the same circuit? If 2 circuits you will need to separate
    – Ed Beal
    Commented Jul 15, 2020 at 20:24
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    @EdBeal These are all on the same main circuit, so any of the light fixtures return power over their neutral to the box and then back to the main circuit via the feeder line. Now on to your suggestion of splitting the bundles, are you suggesting that I have 2 wire nuts bringing together 2 neutral wires each, and then pigtail those to the main neutral? That way each wire nut has 3 wires in it, rather than 5? The truth is that each of the switches also has a neutral so there are quite a lot of things that need to be connected to the neutral line...
    – Jason
    Commented Jul 15, 2020 at 20:41
  • @Jason You're on it! It gets messy. Something to consider may be to replace the entire box with a deeper box. You may be within fill limits according to code, but the extra space of a deeper box just makes life easier.
    – FreeMan
    Commented Jul 15, 2020 at 21:40
  • The neutrals to the switches are probably 18 awg I would put them all on 1 wire nut and a jumper to the other outgoing neutrals and feeder, the grounds Together on outgoing wire nut with a jumper to the switch grounds nutted together then the Hot’s split with a jumper between, a couple of extra wire nuts and jumpers but these fit much nicer in the box I have split the grounds and the neutrals but crimped them so they would always be there could not lift a neutral and not know it. After the inspector saw that I had crimped when splitting the neutral & grounds complimented the neatness.
    – Ed Beal
    Commented Jul 15, 2020 at 21:53

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How many wires depends on the nut, and not just the color of the nut. I have red wire nuts that will only take 5 #14 and others that will take 6 #14 (don't recall the #12 numbers off the top of my head and the boxes are not here as I write.) The listed configurations are laid out in detail on the side of the box/container of wirenuts, and you don't get to be creative if a combination is not listed.

Looking on the website of the de-facto standard manufacturer in the US market (no affiliation other than I use them, and pay full price to do so): Ideal® Wing-nut reds are listed for 5 #12 - their plain Wire-nut reds are listed for 4 #12, the "B-Cap" variant is listed for 5 #12

In any case, if you have more to connect than your particular wire nuts are suited for, divide them up and then add a pigtail between them (which you don't have to count for box fill, but you DO have to count at each end for wire nut capacity.)

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    ...and Harper isn't wrong - 6, even 6 #14s, is a pain to manage into a nut, just from the hanging onto them ad keeping them all lined up while you get it in place.
    – Ecnerwal
    Commented Jul 16, 2020 at 13:20
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Yes, smart switches can be quite annoying like that! There are several ways to lick that problem.

Use a block connector that allows a lot of wires.

They make "stab blocks" that are a row of terminals, each with a "back stab". You jab the wire in, and it grabs it. They make these blocks to take up to 8 wires.

Or the MAC Block Connector: which has 2 larger holes, but each hole takes up to 4 wires. (It's intended for 1-4 copper wires to splice to 1-4 aluminum wires, but if you use them for all copper, I promise not to tell ;)

Now, since the smart-switch wires will be quite a bit smaller than the bulky #12 or #14, and may be too small to work properly in a stab or MAC Block, I suggest bringing all the smart-switch neutrals together on one wire nut, with a "pigtail" jumper to the group of heavier wires. You can easily nut four #18s to a #12.

Daisy chain wire nuts.

Your notion was to split the neutral wire to 2 or 3 "pigtails" then have each one go to another wire nut, which then ties to the various lamps and smart switches. That is perfectly fine, and a very logical way of thinking about it.

However, you can also "daisy chain": Join supply, lamp 1, lamp 2, and a pigtail to nut 2, which adds lamp 3, lamp 4, and a jumper to another pigtail, to nut 3 which has all the smart switches.

It would sure be nice if wire nuts took more than 4 wires! Now, first, with wire nuts, be aware of your "personal minimums". I have nuts that the book says absolutely max out at six #12. I've tried six #12, and let me tell you, no thanks. It's too twitchy, too hard to get right. And I'm good at wire nuts!!! I am more comfortable working with wire nuts in the "middle" of their range; so if the nut says 2-6 #12, I'll use it for 3, 4 or 5. (and go down or up a size for 2 or 6).

But second, yeah, shop around. They make all sorts of bigger nuts - the world doesn't stop at red nuts.

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  • "It would sure be nice if wire nuts took more than 4 screws" eh?
    – FreeMan
    Commented Jul 16, 2020 at 13:01

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