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3 way switch - convert to smart switch

417 Views 4 Replies 3 Participants Last post by  seharper
Hello experts,
I am stuck trying to wire a smart switch for my home automation.

It's for a basement with a ceiling light at the top of the stairs, with switches at the top and bottom of the stairs.

The top of the stairs has both the line and load in it and wired as follows:
Black load from light (painted white) to common screw.
White from light pigtailed to white from panel.
Travelers - black from downstairs boxing white from downstairs box.
Red from downstairs box pigtailed to black line in from panel.

The bottom of the stairs has the 3 wire:
red - common
white - traveler
black traveler

I was able to get the upstairs smart switch to work properly since I identified both the load, neutral and line and then wired them appropriately.

I am confused with what I do with the travelers at the upstairs box and how to wire the downstairs box. The downstairs box only needs power and neutral, but I am unsure that white is truly neutral in this situation. I hope this makes sense and I can add pictures if it would help.

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Make and model of your smart switch?
I believe this is the setup you are describing. The colours between the switches might not be exactly as pictured.

Text Diagram Line Parallel Design
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Thanks for the reply. It's a control4 switch C4-sw1-z. So is the red wire taking power down to the common screw of the bottom switch and then sending power back via the travelers then? So do I not have a neutral in the bottom box then?
Yes - the diagram is pretty close to what I have going on. My wire colors are different.
So I ended up using the neutral from the other switch in the downstairs box, used the red power from the downstairs box and I capped the two travelers in the upstairs box. Working now. The downstairs switch doesn’t need to physically function like a true 3 way switch to work only power so it can send a signal to the upstairs box.

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In the 3-way leg, you need to re-task all 3 wires. Red will be unused, and cap it off at both ends with a wire nut, and (this is the only time you ever) tape the cap onto the wire. Other than that, follow the diagram in the manual, which covers your situation exactly.
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