Can I add Switch/light to existing 3-way circuit?


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Old 02-12-07, 09:57 AM
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Can I add Switch/light to existing 3-way circuit?

Hi,

I would like to add a new ceiling light controlled by its own switch to an existing 3-way circuit that controls two other ceiling lights.

I wanted to tap into one of the wall switches for power and run a new wire to the new fixture. Would this be possible?

Also, How hard is it to remove a stud mounted single gang box and replace it with a dual gang box? Methods? I was thinking of a duplex switch but would rather not go that way.

Thanks for any help.

Lou
 
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Old 02-12-07, 10:06 AM
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Before you start you need to know if this is feasible given the existing wiring. It may or may not be. Tell us ALL the wiring at the switch box. If there are only three wires present (plus hopefully a ground) then what you want to do is not possible (without rewiring). if there are additional wires present then this MAY be possible, but we will need to know the wiring at the other switch, and you MAY have to test something first.

As for swapping this box out and adding a new double gang box, it is possible, but it is not trivial. It;s not hard either.
 
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Old 02-12-07, 10:58 AM
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OK I have two wires coming into the current switch box...

Wire 1: White, Black, Ground
Wire 2: White, Black, Red, Ground
 
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Old 02-12-07, 11:03 AM
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And the wiring at the other switch is?
 
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Old 02-12-07, 11:35 AM
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buggdog Wrote:
"OK I have two wires coming into the current switch box...

Wire 1: White, Black, Ground
Wire 2: White, Black, Red, Ground"

buggdog
Do you own an electrical tester? Do you know how to test for voltage safely?
 

Last edited by hornetd; 02-12-07 at 11:38 AM. Reason: Correct the formatting
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Old 02-12-07, 03:25 PM
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50-50 chance it might be possible. That two wire cable could be the power coming in or it could be the cable out to the light. You need to disconnect the black wire and measure for voltage to ground from the black and white wires.
 

Last edited by joed; 02-12-07 at 03:38 PM.
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Old 02-12-07, 03:27 PM
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Following up on what Tom said, here's my suggested analysis:
(1) Shut off the breaker.
(2) Carefully record all the connections in the switch box, in enough detail so that you're absolutely sure you can put it back the way it was.
(3) Disconnect the black/white cable ("Wire 1" as you call it) from the switch and separate the black and white wires so that they don't touch anything.
(4) Chase the kids and dog from the room and turn the breaker back on.
(5) Carefully use a voltage tester to test for voltage between the black and white wires. A simple $2 neon circuit tester is perfect for this.
(6) Shut the breaker back off again.
(7) Put everything back exactly the way it was.
(8) Turn the breaker back on.

If, in step 5 above, you got voltage, then you can do this. If you did not, then you cannot (without more cable inside the walls).
 
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Old 02-14-07, 03:24 PM
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I'll leave the wiring to the experts. As far as replacing the single box with a double, I've had good luck doing so. If you have a plastic or composite box, I just shut the power off and then break the box out by driving a punch or screw driver down through the bottom and up through the top. You need to be careful that you do not poke a hole through the other side of the wall, though. Once the box is broken out, The nails that were holding it in place can be pulled with pliers. I typically use a metal box as a replacement, just because I have found them to be more sturdy in the remodel application. Put your new box up on the wall and trace the outline. Cut the outline with a drywall knife. I then hold the box in the new hole and mark for 2 holes on the side closest to the stud. Pull it back out and drill a couple of 3/16 holes in the side of the box. Fish your wires back into the box. Take a couple 1 1/2 inch drywall screws, put them in your new holes, and drive them into the stud.
 
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Old 02-14-07, 04:00 PM
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Although vmanbb's approach will work, the more common approach is to saw through the nails. If you have a sawsall, it's easy work. Otherwise, you can slip a hacksaw blade in between the box and the stud and saw through the nails. Yea, it takes a little while.
 
 

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