First of all, my terminology may not be the most official or correct, forgive me in advance.

I have this double-gang box, which holds two switches (switch1 and switch2 in the picture).

Switch1: simple switch, lights the corridor lights. The corridor lights have yet another switch on the other side of the room.

Switch2: dimmer switch, lights the living room lights, it's the only switch that controls the living room lights. BK and YL in the diagram refer to the labels on the switch.

Both lights and switches are connected to the same circuit (When I shut the circuit off, both of them go dead)

I would like to replace switch2 with a smart switch, preferably without running any new cables, but I can't figure out how to rearrange the cables. I've searched high and low for days and can't seem to find a single wiring diagram that matches what I have here.

I have a multimeter available if any testing needs to be done, but again, I don't know exactly what I should be looking for.

EDIT: Not shown in the diagram are 4 bare copper wires coming in the box from out of each of the cables, and attached to screws on the box.

Any help would be appreciated :)

Thank you so much!

My wiring diagram

1 Answer 1


This isn't so hard

Since we're only dealing with switch 2 here, we only have to worry about the wires connected to it, which are merely an always-hot coming in, an always-hot feeding off to the other switch, and our switched-hot going out. The two always-hots get nutted to each other and to a pigtail off to the new smart switch (or to the smart-switch's built-in pigtail if it has one), and the switched-hot in the far right-hand cable gets connected to the switched-hot terminal/lead on the smart-switch. The neutral connection on the smart-switch then goes in with the bundle of white neutral wires already present. Finally, the smart-switch ground wire gets connected to the back of the box, or simply nutted off if your Codes permit switches to be grounded via their mounting screws.

  • @JACK -- thanks, fixed! Jul 3, 2021 at 19:50
  • So I just need to try to replicate the original connections from the dimmer I want to replace? That was exactly the information I was looking for, thank you so much, I'll try that! Jul 5, 2021 at 23:02
  • @GrizzlyFoxCat -- that, and adding the neutral from the smart-dimmer into the neutral bundle Jul 5, 2021 at 23:53

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