Replace 2-way switch w/ 2 3-way switches


Old 10-06-01, 01:51 PM
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Hello, All -

I know this is a very basic question, but I can't figure it out, so here goes. I've got a 2-way switch controlling a light fixture. I want to replace that switch with a 3-way, and put another 3-way on the other side of the wall, so that I can control the fixture from either switch.

I've done the physical work of placing the new junction box, with conduit going from the existing box to the new one. I just can't figure out how to wire the new switches. All the diagrams seem to assume that I've got three wires to work with, when in fact there are only two.

Coming in to the existing junction box from the panel are a red wire and a white wire. The red wire is bundled with two wires: 1 - a YELLOW wire that is routed out through another conduit, and 2 - a red pigtail that goes to one pole of the 2-way switch.

From the other pole of the switch a red wire runs to the fixture. A white wire from the fixture is bundled with: 1- the white wire coming from the panel, and 2 - a white wire routed through the conduit with the previously mentioned yellow wire.

So where is my common? The white wire, yes? Does that mean that I run the white wire to the common pole on the first three way switch? Do I also connect it to the common of the second switch?

It seems clear that the red coming from the panel will go to one pole of the first 3-way switch, a wire connects the two switches, and then that red pigtail to the bundle that connects the yellow and red wires (red to the fixture and yellow out through the conduit).

Is that right?

I appreciate any help, and I hope this is clear.

- Allen
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Old 10-06-01, 02:04 PM
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You're right. This is easy.

Run three non-white wires through the conduit between the switches. I don't know what color wires you have to work with, but let's suppose that they are purple, black, and orange.

At the existing switch, connect the red jumper currently connected to the 2-way to the "common" screw on the new 3-way. Now connect the purple and orange wires to the two other screws (the travellers). Finally, connect the black wire to the red wire to the fixture. Leave the white wires alone.

At the new switch, connect the black wire to the "common" and the purple and orange to the two travellers.

You're done. Wasn't that simple!
Old 10-06-01, 09:23 PM
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John -


Your instructions were completely clear, and I finished up the job in about ten minutes. My wife thinks I'm very manly.

As I connected everything, I could see how it all made sense. I'm glad I asked here before trying it myself.

Thanks again.

- Allen
Old 10-07-01, 07:28 AM
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Thanks, Allen. It is feedback like yours (and that of laffeyku in a nearby post) that makes our participation here worthwhile. It is always frustrating to throw information out into a void and never hear back (even if our advice was wrong. This is, of course, why I have recently changed my signature line to what you see below. I try to learn as much here as I give.

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