I'm trying to replace one of the three-way light switches in my garage with a motion sensor. But I'm confused by the wires on the existing switch. I thought the hot wire goes to the black screw labeled "common" but instead the existing switch looks like this:

  • black screw/common = red wire
  • brass colored screw on same side = black wire
  • brass colored screw on other side = red wire
  • 4th screw = bare copper wire (I assume this is the ground)

My new switch has

  • black = hot
  • white = neutral
  • red = primary load
  • green = ground
  • blue = ?

Which wires should I connect on the new switch?

  • See also This Question, This Question, and This Question might also be helpful.
    – Tester101
    Commented Feb 7, 2012 at 20:26
  • Didn't the new switch come with instructions? It should have a wiring diagram included. What is the make and model of the new switch?
    – Tester101
    Commented Feb 7, 2012 at 20:50
  • 4
    Maybe you should tell us what you expect the motion sensor to do? The switch it replaces would have its operation reversed by the switch that remains ... if it even had the traveler connections needed to make it function in place of a 3-way switch. Normally one wants a motion detector to have full control so the light comes on when there is motion, no matter the position of other switches.
    – Skaperen
    Commented Feb 7, 2012 at 23:11
  • 1
    You should indicate your country of residence. This is because 3-way means different things depending on where you are from. Commented Feb 8, 2012 at 16:28

1 Answer 1


enter image description here

Wiring diagram for Leviton PR180 3-Way Wall Mount Occupancy Sensor.

  • All we have here is a 3-way (USA terms) switch acting as a regular switch (the black wire at the sensor is always hot) to override or control the sensor in some way through the red wire. Perhaps this is a "force light on" connection (though that could have been wired to bypass the switch and go to the yellow wire).
    – Skaperen
    Commented Feb 10, 2012 at 1:08

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