I would like to replace 2 conventional light switches in a 2-gang box, with 2 "smart" light switches, but I'm confused about how to wire them.

The circuit has 3 wires coming in from the top conduit: orange, white, and black. And 4 wires in the bottom conduit: yellow, red, white, and black.

The smart switches want red (load), black (hot), white (neutral), green (ground).

My questions are, where is the green ground wire? (This is new construction within the past 3 years in the US.) And, based on how the existing switches are wired, how should I connect the wires to the 2 new smart switches?

photo of existing wiring and switches

1 Answer 1


It appears that your wiring is in conduit so the metal box will be grounded so a green ground wire wasn't needed. You can run a ground wire from the box with a 10-32 screw into the ground hole in the back of the box to the two switches or if the switches have a metal yoke, just screw them into the box.

The red wire going to each of your existing switches is your hot wire. The orange and yellow wires are your load wires for your fixtures. Your instructions for the new switches will tell you what goes where. If your switches require a neutral, that would be the two white wires connected together with the wire nut.

  • Is the (unused) black the other "hot" phase?
    – Paul Smith
    Dec 5, 2020 at 20:12
  • More than likely yes it is. Are the breakers for this box handle tied?
    – JACK
    Dec 5, 2020 at 20:47

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