Currently, I have an outdoor house light connected to the same light switch as a couple other garage lights (see sketch). I would like to separate the garage lights from the outside house light using two separate switches. Only thing is, the switch is already in a three-gang box. So, I already went ahead and bought a four-gang and I installed it, but now I'm having trouble figuring out how to wire it all. The way it was is confusing to me and I'll try to post an image of how it currently is. Anyway, the other two switches in the box control a light in the house and another completely separate that isn't causing any issues (dimmer switch for kitchen lights), so you can ignore that. So yea, main goal is to add a fourth switch to the box to separate the garage lights and outdoor house light. Thanks!

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2 Answers 2


I actually managed to figure it out on my own. Referring to my picture, I moved the red wire to its own switch and added another white wire and attached it as well. Problem solved. Only downside was trying to pigtail 4 wires into one.

  • Hopefully you used the correct size of new wire nut rather than reusing what was there.
    – JPhi1618
    Commented Aug 22, 2019 at 17:56
  • @JPhi1618 I did not. I wasn't aware. I just Googled it. I'll have to make a trip to the hardware store. I'm just curious (and no I'm not going to keep it the way it is), but what could happen if left the way it is?
    – Zach
    Commented Aug 22, 2019 at 17:59
  • Honestly if the wires have a good solid connection and they never move, it would be OK for a very long time, but the fact is you just really don't know all the variables. Heating and cooling of the wire over time can cause it to loosen without a good mechanical fastener holding it in place. You can reuse wire nuts and it will probably be ok, but for the risks involved and the cost of new wire connectors, it doesn't make sense.
    – JPhi1618
    Commented Aug 22, 2019 at 18:05
  • More direct answer - loose wires cause arcing, and electric arcs are super hot (like a welder or lightning). Heat in a confined place causes things to burn, but at the very least your lights go out and you have no idea why.
    – JPhi1618
    Commented Aug 22, 2019 at 18:07
  • Also, not sure what's going on there, but all those ground wires should be bundled together. Some people believe grounds are not important for lights, but if you want to fix problems while you are there, fix that. And, you can't have two wires under one screw like in that picture. I think you moved the red wire, but keep that in mind. Whoever wired that box originally had very little experience or knowledge (sorry if it was you), so be careful and don't assume anything is correct.
    – JPhi1618
    Commented Aug 22, 2019 at 18:10

Few cleanup issues

You need to hook up the grounds. Given the stupid short wires, all these cable runs must be replaced OR go back to a metal box and ground them to the clamps like the last guy.

You got the memo on not double stacking screws on wires, good. You see how roached that looks, anything shabby like that is outlaw, NEC 110.12.

4 or more wires should use a red wire nut. They should survive a pull test. If you need tape to make them stay put, fix your technique instead.

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