Can I add an occupancy sensor to a 3-way circuit?

by Jonah H.   Last Updated June 09, 2019 21:21 PM

If I replace one switch in a 3-way circuit with an occupancy switch, would this cause the occupancy switch to work in reverse (or not at all) if the regular switch was toggled?

If so, would the best solution be to remove the second switch from the circuit, or just put two occupancy switches in? The switches are nearby enough that only one is necessary for proper operation.

Answers 3

Wouldn't it be easier to just replace it with a 3-way occupancy switch

You can take out one of the switches but this would keep you from having to cap a box or redoing your wiring and give future flexibility.

So you will need 2 3-way occupancy switches since if you just replaced one you could possibly be turning it off.

May 01, 2013 05:44 AM

DMoore is spot on about using the 3-way occupancy sensor, but off a bit about needing to replace both switches with occupancy sensors. The occupancy sensor installation instructions should show how to connect the device to a 3-way circuit, without replacing the other switch.

Here is an example wiring diagram from the Lutron Maestro Occupancy Sensing Switch installation guide.

3-way wiring diagram

However, occupancy sensors only work if they can see you. So if the switch locations are not within line of sight, you may have to replace both switches depending on your operating preferences.

May 01, 2013 11:28 AM

Tester101, Thank you so much for the diagrammatic. It was the best one I have seen and better than the one that came with my switch (Dependable Direct 3-Way PIR Vac and Occ Wall Switch Sensors 2-pole). The one you posted had two black wires coming out of the switch and this one has one black and one red, so it did take some tweaking to get it right. But mostly knowing that I had to jumper the two wires on the manual switch was very helpful.

But now I still have a problem. The manual wall switch seems to be the master (if it's off there's no power to the sensor switch on the other end of the hallway), which is fine. I decided to keep the manual switch there because I don't want the light to be triggered all the time by random movement in the other room. I have the sensor farther down the hall so that it will only turn on if someone is actually entering the hall. My problem is that no matter how I set the sensitivity and ambient light settings on my new switch, it only turns on when I manually press the button. It has been that way for a few weeks (once I got it to work after MUCH trial and error, I didn't want to mess with it), but today I thought I should take another crack at having the motion sensor function property.

I know that this is not the same product that you have, but can you perhaps enlighten me if there is a combination that I need to achieve on the sensor switch? I think it's wired in a way that the sensor has no juice.

I have kept notes on the combos I have used and I think I've exhausted all of them. Any help would be appreciated.

Lisa Sturm
Lisa Sturm
June 09, 2019 20:57 PM

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