I think the black wires with the white and blue caps are the hot ones, and maybe the brown wire is ground or neutral?

I'm trying to replace it with whats in the second image but not sure what the SW1 wire is (pass through maybe)?

Current dimmer switch

new dimmer

  • 1
    Check out some of the answers and pointers on this question. diy.stackexchange.com/questions/166670/…
    – J Crosby
    Commented Aug 6, 2019 at 17:33
  • How is grounding handled in the rest of the house?
    – Valkor
    Commented Aug 6, 2019 at 20:02
  • this is the first one i was trying to change myself, i think i may have had an electrician add one somewhere else that i can look at Commented Aug 6, 2019 at 20:29

2 Answers 2


Someone else will probably post a more complete answer soon, but you need to figure out which of the black wires on your old switch is always-hot, and which is hot only with the switch on. Always-hot connects to live on your new switch, and switched-hot connects to SW1. Neutral gets added to the white wire bundle in the back of the box, and ground connects to a screw into the metal chassis (because the conduit is your ground here).


The light colored insulated wires are the neutral. They connect to the white on your switch. I might see two bare wires tucked behind the others. If they are there, those are the ground. They connect to the green on your switch.

Turn off the breaker to that switch and disconnect both black wires. Turn the power back on and use a multimeter to determine which is hot and which is the switch leg. The hot black wire will go to "live" on your switch. The other black wire goes to your light fixture and connects to SW1.

  • I don't think there's bare wires back there -- that looks like the neutral just loops around a few times. In this case the ground is the metal conduit, so the ground wire needs to be attached to the metal box.
    – Nate S.
    Commented Aug 6, 2019 at 19:57
  • @NateStrickland Agreed. There's a lot of old crud in there.
    – Valkor
    Commented Aug 6, 2019 at 20:01

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