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Converting to a Smart switch - figuring out different wires

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  • Converting to a Smart switch - figuring out different wires

    Hi I'm James. I am a newbie to this.
    I am trying to replace my 3way toggle dimmer switches to an alexa enabled 3way toggle smart switches.
    I have a problem with new wiring.
    There are only 4 wires : 1 white, 1 black, 1 red and 1 green
    Existing configuration : The black wire was connected to top right and white was connected to lower right. Red was connected on lower left and green was on the lowest mid.
    Green for sure is ground.
    White wire might be a hot wire - 120v with a tester.
    Not sure about the black and red wire.

    So here's the question :
    How can I find a neutral wire? How can I tell which wire is the load and which one is line wire?
    How difficult / expensive is it to get a neutral wire for new switches? - do I need to hire an electrician?
    Thank you!

  • #2


    • #3
      First thing to do is vacuum all the junk out of the box. That's a fire hazard.
      "It's a table saw, do you know where your fingers are?" Bob D. 2006



      • #4
        I advise you hire an electrician. It shouldn't be too expensive. He needs to change out at least a portion of that cable.
        The insulation on that nm cable is the old cloth covered type and looks rather bad. Further more it is not rated 90c for feeding a light fixture. And switch outlets now need a neutral per code for just your reason.
        3 way light switches have a black screw which is the common pole inside switch. On that black screw you have a white wire, or a white wire with black tape on it. The white wire with tape should be the hot and the black screw on the other switch should have a white wire that feeds the lighting outlet(s).
        The other screws red and black are called travelers and they go from switch to switch.

        This is the usual wiring but it can vary.

        Again, I advise you hire an electrician because this can get tricky. 3 way switches are commonly wired wrong by a handyman so don't take anything for granted.

        Btw, those old work boxes may have exceeded their fill capacity.


        • Bob D.
          Bob D. commented
          Editing a comment
          Yeah, they're full of sawdust. :-)

        • johncameron
          johncameron commented
          Editing a comment
          The dust/ fire hazard is likely because the pastic wire clamps at the top of box are missing because they were completely knocked out.