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I've got a light downstairs with the switch upstairs. I want to add a switch downstairs. I have access to the light's wiring and can add the switch easily there. I don't want to rip up the drywall though to put a 3-wire cable in.

Is there any way to use a single pole/2 wire switch in a 3-way setup?


This is a box I currently have access to and could wire the near-by light switch (I've got an unused one very close). I've verified that one cable goes to the light and the other to the switch.

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  • I take it the cable that you can't replace is the existing one to the upstairs switch? Also, can you get us a photo of the inside of the existing light fixture box? – ThreePhaseEel Mar 5 '17 at 0:02
  • That box is likely not going to be of any use whatsoever -- I need to see what's inside the actual box that the fixture is attached to – ThreePhaseEel Mar 5 '17 at 2:06
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Best way would be to use a 'smart' switch of some sort. There are many on the market. Some are wireless (radio frequency), some use signals on the powerline. These switches require hot and neutral.

The downstairs one would be wired as a normal switch and it would directly control the light. The upstairs one would just be configured to control the other switch, and the two conductors would carry hot and neutral.

  • I ended up (reluctantly) getting the radio switch. I really, really dislike it, but it works as advertised and solves my problem – Daniel Mar 11 '17 at 23:36
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If there is no way to leave the downstairs without passing by that switch you could just wire the switch in series with the other one. That way you could turn the light off or on from either switch. However, the other switch has to be in the on position at the time. So, when using the stairs you turn the light on in the direction of travel and turn it off when get up or down. However, if another person wants to use the stairs they will be in the dark.

If this is not acceptable you could look for wireless switches that use a transmitter and receiver to set up a three way switch without the added wiring.

Good luck!

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Another possibility is to install a relay. Either switch controls the relay, and the relay controls the light. The switches would probably have to be momentary type, and the relay would toggle between on and off.

  • can you expand on that? I haven't found anything on relays other than this sort of stuff forum.mysensors.org/uploads/… which requires 3 wires – Daniel Mar 5 '17 at 2:44
  • @Daniel -- we can't give you more specific instructions unless you tell us what's going on inside the boxes – ThreePhaseEel Mar 5 '17 at 3:40
  • @Daniel, I worked in an office once (had a job there as opposed to being employed there) that had momentary switches on opposite ends of the office that controlled a relay that in turn turned the lights off and on. Exactly how it was wired, I don't know, but it's obviously possible. – BillDOe Mar 6 '17 at 20:44

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