I want to replace one of the two 3-way switch that's in my laundry room. I have the Decora D0S05 model switch: PDF instructions here

The issue though is that the switches beside it is linking up the black wires with it too. My motion sensor has 5 wires:

  • ground
  • ground/neutral
  • black (line/load)
  • black (line/load)
  • red/yellow (typically counted as a traveler)

The middle black wire is where the power is coming from, if I disconnect it to the left black wire, the garage light does not turn on.

electrical box where the 3 switches are

Closer look with the two switches on either end of the wiring of the first box.

electrical box with the two switches in view

Within the second 3-way switch's box -- there is one other switch that borrows power (it's confirmed because if I turn off the breaker, the 3rd switch can still turn on its set of lights).

second electrical box with 2 switches that draws power from the same source

I have it to the point where it can periodically have light, but it turns off right away. It does not actually detect motion as it would have this faint red light when motion is detected. Please help...

  • 2
    The diagram does not make any sense. Do all of the other switches besides this Motion Detector/3-way and its remote 3-way work? Based on the diagram, I don't see how that is possible. Mar 9, 2023 at 0:39
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    The diagram is clearly wrong. Please recheck and update. (It looks like what you were trying to draw is one switch which feeds a three-way pair which then feeds the light, with the second and third being the three-way... but that isn't what you've drawn.)
    – keshlam
    Mar 9, 2023 at 1:39
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    @manassehkatz-Moving2Codidact the diagram are the main wires that I have access to. Everything else in the electrical box is already connected. I updated the photo to provide a clearer picture. Currently from left to right... #1 works when connected to power #2 is the new motion sensor switch that's connected to a 3-way switch at another area #3 is disconnected from power as I want to isolate it till I figure out the motion sensor switch, but it would technically connect to the middle black wire to turn on the driveway light.
    – Ian K
    Mar 9, 2023 at 20:29
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    It appears that you've now created two accounts and that's why you couldn't edit your original question without it going into the review queue. Please follow the instructions here to get the accounts merged.
    – FreeMan
    Mar 10, 2023 at 13:36
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    @ThreePhaseEel the first one from the left of the right wires is the set that goes with the red/white. The second black wire coming out of the blue ish tinted skin leads to the light that I want the motion sensor 3 way switch to control
    – Ian K
    Mar 12, 2023 at 2:13

1 Answer 1


Switch spurs

The setup you have, where always-hot (power) and switched-hot (the light) are both brought to the same switch box in separate cables, is what I call a three-way switch spur. As a result of this, you're limited in where your motion sensor can be placed by the fact you only have 3 wires between the two switch boxes. Fortunately, though, since you're putting the motion sensor at the first switch box, it shouldn't be too much of a challenge wiring this into your 3 way circuit.

To hook it up correctly, as per the instructions:

  • Remove the green sleeve from the white wire on the motion sensor and connect it in with the bundle of white wires in the first switch box. Do not separate this bundle!
  • Connect the green/yellow grounding wire on the motion sensor to the bundle of bare grounding wires in the first switch box.
  • Connect the red and white wires from the cable over to the second box to the black incoming hot wire, one of the black line/load wires on the motion sensor, and the two black pigtails off to the other two switches in the first box. This wires up the two same-colored terminals on the switch in the second box.
  • Connect the black wire in the cable to the second box to the red/yellow traveler wire on the motion sensor. This wires up the differently-colored terminal on the switch in the second box.
  • Connect the remaining black wire on the switch to the black load wire off to the light
  • Button everything up and turn the breaker on
  • Make sure the light works properly from the pushpad on the motion sensor, then program the motion sensor to work the way you want it as per the instructions.
  • I tried this, the motion sensor works but the 3 way switch that it's connected to no longer works
    – Ian K
    Mar 13, 2023 at 16:41
  • @IanK read the instructions as the 3 way switch is being basically used as an input to the motion sensor now (toggle once to turn on, toggle twice to turn off) Mar 14, 2023 at 3:17
  • Understood. Will test out the toggle once vs twice sometime this week but I am super glad the motion sensor actually works. Much appreciated nonetheless!
    – Ian K
    Mar 14, 2023 at 12:07

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