I'm looking to install a Leviton Decora smart dimmer, 2nd gen to replace a switch in my master bedroom. I unscrewed my current switch from the wall and found the following set up - 3 black wires, 2 white wire. Two of the black wires are screwed together with a wire connected to the switch. The other black wire is connected to another part of the switch. The white wires aren't connected to the switch, just to each other as a pass through.

On the new switch, I need to connect to line and load connections, a neutral connection and a ground connection.

From other posts it looks as though I can rely on the metal of the outlet to ground my switch given there's no ground wire.

What should I look to do with the other wires? I have a voltage tester being delivered in a couple of days too.

enter image description here

  • Looks like switch controls two fixtures.
    – user263983
    Commented Oct 5, 2021 at 0:38
  • 2
    @user263983 More likely one device, but hot power also goes to another device.
    – crip659
    Commented Oct 5, 2021 at 0:43
  • 1
    @ElFik Do not assume the metal box is grounded. To be grounded, there must be a ground wire or metal conduit attached to the box that goes to a known ground(usually the panel).
    – crip659
    Commented Oct 5, 2021 at 0:47
  • 3
    @user263983 What is supposed to be and what is can be two different things. Assuming can kill.
    – crip659
    Commented Oct 5, 2021 at 1:09
  • 1
    @crip659 We are guessing but OP may check it and get solid knowledge. Metal connector with nut should be inside the box. Just take a look.
    – user263983
    Commented Oct 6, 2021 at 10:48

2 Answers 2


See the solo black wire going to the switch (which is not pigtailed to other blacks)? You would be wise to mark that with red electrical tape. It's not a code requirement, but it will make things in the box much, much easier to understand.

At that point, red will be switched-hot, blacks will be always-hot, white will be neutral, and that will match the colors on most smart switches.

You will need all new wire nuts. Those old ScotchLoks should not be used twice. Or once, really. 3M makes countless wonderful products, so we can forgive them for making one bowser.


Check for sure which wire is power comes. Looks like one with pigtail. Connect what pigtail to power terminal of dimmer. White wire, make pigtail and connect to neutral of dimmer. Single black wire to load terminal. Where is no ground wire in box, considerably the conduit is metal tubing. So the box is ground, use the screw inside.

  • Should I attach the ground wire from the switch to the metal box, or is it OK to rely on the screws to ground the switch for me?
    – ElFik
    Commented Oct 6, 2021 at 8:19
  • 1
    I do not understand what you mean by rely, but consider the screw on the box as ground if it is metal tube comes into box.
    – user263983
    Commented Oct 6, 2021 at 10:45
  • I've come back to this project after a vacation. Have confirmed that the metal box is ground. How do I securely attach the ground wire of the switch to the metal box? Tape with electrical tape?
    – ElFik
    Commented Nov 8, 2021 at 4:30
  • @ElFik yes, switches only can ground via the screws. Receptacles can't, unless they are marked self-grounding, which happens on the better made ($3) receptacles. Commented Jul 2, 2022 at 3:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.