Electrical Wiring in the Home/Faulty 3-way switch


QUESTION: Trying to repair a 3-way switch in my hall. Typical problem... Turn the switch on in one location then turn it off in the other location. I go back to the first location and the switch doesn't work.  I opened up both switch boxes and I was able to identify the common/hot wire in the first box. So the other 2 wires are the traveler wires. So with the power off I connected the 2 traveler wires in the first box and then went to the second switch box with my multi-meter to identify the traveler wires there. Well I tested all three wires in the 2nd switch box but none of the combinations sounded off the multi-meter. So I looked in the 2nd switch box and there is only 1 3-wire cable. The first switch box had 2 wires- a 2-wire cable from the panel that has the black common wire and the 2nd 3-wire cable that runs to the 2nd switch box. The 2nd switch box only has the 3-wire cable coming in to it... No wire out to the light.. So I'm confused as to how this light is wired up. Is it possible that the 3-wire cable runs to the light and then runs to the 2nd switch box? As I said, when you flip each switch individually the light turns on and off but you have to use that one switch. You can't turn one on and then turn the light off with the 2nd switch.. So how do I fix this so that both switches operate the light like 3-way switches are supposed to.. I'd really appreciate your help on this...

ANSWER: Usually when that happens the traveler wires are mixed up with the other ones. Make sure that the two wires that are on the same color screws in box one are also on the same two color screws in box 2.

Yes, it is possible to have only 2 cables in the first box, and one in the second.  It would be if it is a switch loop. None of the wires are neutral wires in either box.  The two wire cable would both be hot wires, and both would connect to the odd colored screws.  One directly in the first box, and the other one connected to a wire going to the second box which would connect to the odd color screw in the second.

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QUESTION: Thanks Bob.. Here's what I did...
In the first box, I have a 2-wire and a 3-wire cable.  Since it would be a switch loop, I connected the white of the 2-wire to the common screw on the switch.  Next I connected the white and also the red of the 3-wire to the brass screws on the switch.  The 2 blacks were tied together with a wire nut.  
Next I went to the second box where there is only a 3-wire cable.  Again I connected the white and also the red to the brass screws.  The black on the second box is connected to the black or common screw.
I put the power back on and still have the same issue with the switches.  The switch that turns on the light also must be the switch that shuts off the light... so they're still messed up.

I pulled down the light fixture and check those wires.  There are 2 cables, both of them 3-wire in the light fixture box.  Both red and also the black are tied off with wire nuts; red to red and black to black.  The 2 remaining white are each tied to one "leg" of the light fixture..

Could this be my problem?  If so, how do I fix this problem...

Thanks for your help Bob.. This light/switches have not worked properly since I've been in this house.  I would like to finally get them working properly as I am tired of running up and down the stairs all the time flipping switches to get the light to turn on or off...


OK, it now looks like the wiring is source/switch/light/switch.  The black and red wires are your traveler wires, and they need to connect to your screws that are the same color on each switch.  At the first box, the black from the panel connects to the odd color screw.  The white connects to the other white wire which goes to the light. At the second box, the white goes to the odd color terminal, which eventually goes to the black power of the light.  Leave the wiring at the light alone.
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Electrical Wiring in the Home

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Bob Sponaugle


Just about any home wiring question. (not appliance repair) I have done all kinds of home wiring for myself, including adding a new breaker box, etc. Please, questions from North America only. Please be specific with details.

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