# Combine two independent switches into 3-way?

Currently I have two independently powered switches powering two lights. The dining room is a single pole switch controlling the light. The kitchen used to have two 3-way switches controlling the light prior to removing a wall. After removing the wall, I just capped the old 3 wire in the basement so the remaining 3-way switch is the only control of the light. What I'd like to do is have both existing switches turn on both lights simultaneously but I'm not sure how to (or if I can) accomplish this.

Here's a rough text diagram of the current set up

Dining room: Feed ----- single pole switch ----- light

Kitchen: Feed into light --3wire ---3 way switch --- 3 wire -- terminated in junction

One thing that seems odd to me is that there's a 3 wire from the light to the first (and now only) 3way switch. Let me know if this makes sense.

Thanks Dan

The black coming into the hall switch is what provides power here. I think it I tap into the red wire coming off the top of the 3way switch and a neutral, I can pass that power to the dining room light.

• Can you post photos of the existing setup? Feb 12, 2017 at 23:38
• Do you mean that there is a 3rd wire? black/white/red/bare from the light to the switch? This would be a 3-way setup. If one of the wires (black or red) are not connected, then it was a traveler from the previous setup of 2 3-way switches. If it was converted to a single switch then it would make sense. Feb 13, 2017 at 2:24
• Yes, there's a 3rd wire from the light. The switch is technically still a 3-way but the wire that used to go to the end 3-way is capped. I'll try and post a picture or better diagram tomorrow if still not clear, but I'd like to so how use the terminated 3 wire in the junction box to also power/switch the dining room light while converting its single pole switch to a 3-way.
– Dan
Feb 13, 2017 at 2:41
• I added a diagram of the current setup to the post. Let me know if you need clarification.
– Dan
Feb 13, 2017 at 14:57
• You'll need to run a new cable for this for sure -- between which two boxes would it be most practical? Feb 14, 2017 at 0:17

If you use the hallway circuit to power the three-way circuit, you must run four conductors (plus ground) between the two switch boxes.

(If you needed to use the dining room feed you would have to run five conductors.)

With this circuit, you abandon and cap off, or remove completely, the feed cable to the dining room switch. You also abandon and cap off, or remove completely, the useless stub cable to the terminated j-box. I have omitted those cables from my diagram.

I have omitted the fault ground wires from the diagram, but don't omit them from your house.

Using the hallway light j-box as your power source is safer than using the dining room switch j-box. With power coming from the old dining room end, the two-gang (the one with the hallway switch) would have live wires from two separate circuits. A future electrician might not know that he has to flip two circuit breakers to make the box safe to handle.

• This makes sense. Could this not be accomplished using a two wire to go from the existing 3way switch (using the top red and a neutral) to the dining room light? Then I could make use of the currently terminated 3 way. I'm fine abandoning the current feed to the dining room light.
– Dan
Feb 15, 2017 at 12:16
• Also, that diagram is awesome!
– Dan
Feb 15, 2017 at 12:17
• BTW -- pull out the abandoned cables and terminate them in their own single gang boxes -- this will keep the box fill in the switch boxes manageable. Feb 15, 2017 at 12:45
• @Dan: Yes, there are many other ways to wire two lights to two three-way switches. I think my diagrammed suggestion is the best way to avoid forcing some future maintainer to spend two days trying to describe the circuit over the internet. Feb 15, 2017 at 13:07

This diagram does not make sense, nor would it work. A 3-way has a single wire on one side-- either tied to hot input; or to the lights, and a pair of wires that go to the other 3-way switch. A 3-way wired directly to a light fixture is being used as a 2-way switch.
Meanwhile, that 2-way connected to the hall light is a disaster. Unless both the 3-way and that 2-way are "on" neither light will get power, according to your diagram.

In any case you won't be able to control the dining room light without pulling wires from its switch (which presumably you'd replace w/ a 3-way) to the other 3way switch, and moving both the kitchen and dining light fixtures' hot inputs to the output of the pair of 3-way switches.

• I agree it doesn't make sense but that's how it's presently configured, which caused by initial confusion. Both lights do work independently of each other I just have no clue why 3 wire was going up to the lights. I may have to pull those fixtures down to see what's going on in those boxes.
– Dan
Feb 13, 2017 at 19:55
• If power were coming from the hall light would that make sense? Going to try to pull that down later...
– Dan
Feb 13, 2017 at 21:49
• power appears to come from the hall light fixture itself. The red wire from the hall switch connects to the black on the hall fixture. All the blacks are capped within the hall fixture box.
– Dan
Feb 14, 2017 at 3:11
• Also the red and black are capped in the Jbox in the basement so that explains how power gets to that switch. Given these findings, it seems I'd want power from the red wire above the 3 way and the neutral to run to the dining room light as well. Does that make sense?
– Dan
Feb 14, 2017 at 16:48