I currently have this configuration in my home and I would like to replace the left switch with a wemo three-way Smart light switch. I'm not able to find any information online on how to do this with the smart switch. It works with 2 regular three-way switch.

Update: I uploaded a picture of the outlets for all to see.

Box 1 contains 3 cables entering. 14/2 Source, 14/2 Light Fixture, 14/3 going to Box 2.

Smart Switch:

  • Source power goes to black to Common on Switch 2
  • Traveler 1 on Smart Switch to Red traveler going to bass screw on Switch 2
  • Traveler 2 on Smart Switch to White traveler going to brass screw on Switch 2
  • Ground to all ground
  • Source Neutral to Light Fixture and Smart Switch
  • Source Power to Black cable going to Common on Switch 2

Box 2:

  • Red travler to brass screw
  • White traveler to brass screw
  • Black power to Common
  • Ground to Ground

Issue: If Switch 2 is "ON" then smart switch can turn the lights on and off. If Switch 2 is "OFF" then smart switch cannot turn the lights on.

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  • I mean it looks simple enough to wire the travelers, neutral, ground, and line/load from the switch to the light fixture but it isn’t working! T1>T1,T2>T2,G>G,N from the source to N from fixture & smart switch, Power from source to C on switch 2 and line/load on smart switch to fixture.
    – xa1200
    Feb 14, 2020 at 8:55
  • Can you post photos of the insides of the boxes involved please? Feb 15, 2020 at 1:02
  • Hi, I uploaded a picture with a summary on what's going on.
    – xa1200
    Feb 15, 2020 at 2:19

3 Answers 3


You would wire up the smart 3-way switch as shown in the picture below. I am showing the connectivity and did not show the various wire nuts that will be required to connect the wires on the switch to the existing wires in the box.

You cannot install the smart 3-way switch in the box at the right because there is no neutral there.

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It's very common for people to snatch one of those diagrams off the Web, and say their wiring is exactly like that. Probably not "exactly".

The first task is to identify the travelers. Wire colors in 3-way circuits can be anything. Each of the old 3-way switches will have 2 brass screws and 1 black screw. I strongly recommend color-coding in situations like this, and to mark the traveler wires with yellow tape. Both travelers can be marked the same since they are interchangeable. Do this on both switches; they should be the same pair of colors on both ends.

If you've already dismantled the old 3-ways, put them back on temporarily, wired so they work absolutely 100% on both ends. When they do, mark the travelers. Don't shortcut this process or make assumptions; they will blow up in your face later.

Now look at the third wire that is in the cable with the travelers. Is it white? Does it go only to other white wires? If so leave it alone. Does it go to a switch or to any black wires? If so, re-mark that white wire with black tape on both ends -- this mark is required by law. If you know for a fact that it is switched-hot (hot only when the light is on), I prefer to mark it with red tape.

Now, with those marked, look at any white wires that remain. Do any of them go to switches or to black wires? If so, then Houston, we have a problem. We will not be able to install this switch on this 3-way complex. Stop entirely; you cannot continue. You will need to pull additional cable, post pictures of the insides of your boxes and we can advise.

Ok, so now all travelers are marked, as are any white non-neutral wires. We know we have power coming through a 3-way box, because white wires remain. At this point, this is straightforward.

On the Wemo, mark the red and blue "traveler" wires with yellow tape.

  • Add green to existing bare or green ground wires.
  • Add white to existing white neutral wires.
  • pull the 2 yellow travelers off the old 3-way and attach it to the yellow wires on the Wemo. Which you re-marked.
  • one wire remains on the old 3-way. Remove it and attach it to Wemo black.
  • hello, I uploaded a picture so you can see what's going on.
    – xa1200
    Feb 15, 2020 at 2:27

My wiring was fine. The smart switch was defective. Replaced it with a new one and it’s working.

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