Re: Adding 3-way switch
m_albertson, if you can go back in time to before the adoption of the 2011 NEC, you can do it the way I first posted.
IF by some chance your local AHD (Authority Having Jurisdiction) has not yet adopted the 2011 National Electrical Code, your job is easier. Otherwise, you'll have to replace the cable from the light fixture to the existing switch with 12/3 (or 14/3) and run 12/4 (or 14/4) cable from the existing switch to the new switch. In this case, which color is connected where will be different than in my first post.
The best thing to do is contact your local electrical inspector and ask what he will approve, in writing if possible. Then when you get your inspection, request that particular inspector do the inspection. Or you could just hire an electrician and let them deal with the bureaucracy.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.