Three way switches with 12/2 wire?

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You can use the white as a switch leg if it is marked with black tape or something. That is the only way to do it if your hot feed is at the light box. (Well you could run 2 cables or a 12/3 but then you have unused wires which is just as, if not more, confusing later on). I always do my switch leg connections so that I end up with a black (switched) and white (neutral) coming out of the light box. If you have power at the switch box then you don't have the problem.
From what I have experienced it seems like most people don't bother to mark the white switch legs properly, even on relitivly new construction. I have seen a bit of scribble with a ball point pen or 'sharpie' which 9 times out of 10 gets painted over by the painters. Kevin

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Kevin Ricks wrote:

As Kevin said runs to a regular switch (or 3 way switch) can be made with 2 (or 3) wire Romex. The white wire can be used as the hot wire feed to the switch (but not the switched wire). As Kevin said the wire color must be permanently changed everywhere it is accessible. (2005NEC 200.7C2).
bud--
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snipped-for-privacy@gmail.com wrote:

Everything you've described so far "works" circuit wise, but probably not code wise.
But you didn't mention what's with the white of the incoming power at Switch 1. Does it just dead end there or does something else connect to it?
And, what does the return (hopefully white) from that unrelated light controlled by the second switch in the "Switch 2 box" connect to? Hopefully it comes back to that box and connects to the white of the "second power source". If it doesn't, you may have even more of a mess than you've described already.
But, what do you mean when saying you want to wire the added light "between Switch 1 and Switch 2"? That question could be taken a few different ways.
Anyway, I agree with what the others have already said. What you've described is a ghastly abortion and shouldn't be left that way to trap someone in the future.
I couldn't help noticing you never once mentioned anything about ground conductors. Is the place so old that those aren't used?
Since you felt you needed to ask here, I hope you'll follow the majority advice you'll undoubtedly be receiving. A little knowledge can be a dangerous thing.
<snipped>
Jeff
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Jeffry Wisnia

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Thank you for the feedback and suggestions. The "second power source" in box 2 is on a different circuit breaker in the same breaker box. I had to flip two breakers to make sure all wires in box 2 were dead. I imagine the other three-way switches in the house are wired this same way. ;-( I guess I should fix them all. Did they not have codes 35 years ago?
After I fix the "second power source" problem by replacing the 12/2 with a 12/3 cable between the two switches I plan on pulling an additional 12/2 cable to box 2 and pigtail it with the switched outlet's cable and pull it up to my new light.
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snipped-for-privacy@gmail.com wrote:

The hot and neutral are from different circuits. In addition to being a code violation as wired the neutral can be overloaded if the 2 breakers aren't on different phases. Your solution is the right one.
bud--
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On 20 Jan 2006 07:52:52 -0800, snipped-for-privacy@gmail.com wrote:

There is a 50/50 chance you are overloading the neutral.
Kevin, this keeps getting worse doesn't it. Keep up the good work. You are right so far.
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From box 2 connect the black of the new light cable to the black wire on the switch common. Connect the new white wire with the neutrals in box 2. The only thing I would worry about is if the 2 hots of box 1 and 2 are both on the same breaker. They should be. You may need to change out box 2 to a deeper box.
You could run your new light cable from box 1 if you want to reconfigure box 2 so that the outlet is full time hot.
Kevin
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http://doityourself.com/electric/h2installswitch.htm
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