Mysterious 3 Ways Switches

malibujason79November 20, 2010

Hello everyone and thanks for taking the time to read my post. Bought a house a few months ago that is 7 years old. In the main living area I have two 3-way switches that I have no idea as to where they go or what they control. If I take my fluke voltage alert tester "lights up red when voltage in present" remove the switch covers and operate the switches, I can get it to light on and off when I toggle the other switch. So I know these are tied together. How can I go about finding what these switches control? The wiring is going through the walls not the attic or basement, so I can't physically trace them that way. Any input would be great.


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An outlet somewhere (I'd say in the same room) intended for a table lamp.

    Bookmark   November 20, 2010 at 2:27PM
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To expand on pharkus's answer-
It might just be 1/2 of an outlet that is switched, so try a lamp in both sides of the duplex outlet (top and bottom).

    Bookmark   November 20, 2010 at 6:34PM
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Sorry I should of mentioned in my first post, that was the first thing I did. I also went around with one of those little 3 light wiring testers to make sure all the outlets are wired corectly. I'm wondering if there should be another 3-way switch some where in the circuit that was replaced with a single switch. Or maybe an outlet was replaced some where and they didn't break the little clip on the side of the outlet.

Thanks for the replies guys, keep them coming.


    Bookmark   November 20, 2010 at 9:01PM
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The most likely explanations have already been offered. It could be that the original wiring has been altered since installation. Seemingly mysterious switches are often installed for good reasons. I did one house where the owner wanted a 3-way switch for the front porch light with one switch in the rear hallway of the house so that the light could be operated with no one anywhere near the front door.

    Bookmark   November 21, 2010 at 7:47AM
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To add further on the possibility of it being for half of a duplex receptacle, if the receptacle was previously replaced and the 'common hot' tab not removed, it would negate the function of the switches and the receptacle would remain hot.

    Bookmark   November 21, 2010 at 9:23AM
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So if the common hot tab was not removed, voltage would sent back to the switch from the outlet correct ? On a 3-way switch, how many leads on the switch should be hot?

    Bookmark   November 21, 2010 at 8:05PM
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The first 3-way switch will have one hot lead coming in and one hot lead going out. The other outgoing lead would be hot, instead, if the switch were in the other position. The second switch will have two attached wires coming from the first switch, one of wich will be hot one hot, and depending on the switch position, one or no hot leads going out. To better visualize and understand how this works, I recommend getting an illustrated book on basic wiring. (Sorry, I'm not up on how to post graphics here.)

    Bookmark   November 21, 2010 at 8:30PM
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Switch one looks to be wired and working correctly. Switch two also looks to be wired correctly however the commom terminal which should be my output to what i'm controling is hot all the time. So I removed the common wire from switch two and connected a test light. Both switches work the test light as they should. So now I need to figure out what these switches control to see why I have an extra hot back feeding to my switch. I'm still think its a receptacle somewhere. FYI, I used this wiring diagram to help me trouble shoot this problem.

    Bookmark   November 21, 2010 at 10:49PM
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... the commom terminal which should be my output to what I'm controlling is hot all the time.

I think Randy called it.

    Bookmark   November 22, 2010 at 2:58AM
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Its goes to an outlet. Broke the tap and everything is working just fine, thanks for the help guys.

    Bookmark   November 22, 2010 at 8:44PM
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Cool. Keep an eye out for other mistakes, that's kind of a biggie.

    Bookmark   November 30, 2010 at 5:18PM
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