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I have a fairly specific question related to three-way switches. While I understand in principal how they work and how to wire them (I think anyway), my specific wiring is not generating the expected results. Here is the current wiring:

----------       Switch 1:       Switch 2:               ---------
| Power  |---B---Common          Common------W---X---B---| Light |
| source |---W   Traveler----B---Traveler            W---|       |
----------   |   Traveler----R---Traveler            |   ---------
             |                                       |
             ----------------X------------------------

Legend:
B = Black wire
W = White wire
R = Red wire
X = Splice/wire nut

The expected result is that both switches can independently control the light. The observed result is that one switch overrides the other (the overriding switch must be on for the light to be on, and, if it is on, the other switch will cause the light to flicker when toggled, but will not actually turn it off).

Given the above, am I doing something wrong or could one or both of my switches be faulty? (They are brand new, but at this point I'm having difficulty finding another explanation.) Thanks!

  • 1
    There seems to be a problem with your diagram. At the end near the light, you have two white wires. One attached to common, and one carrying through from the first switch. – Tester101 Sep 2 '14 at 17:17
  • The diagram is correct. The junction box with switch 1 has three cables coming into it. The one from the power source (B/W), the one to the light (B/W), and the one to switch 2 (B/W/R). Consequently, I am using the white wire there to route power back from switch 2 and splicing it into the black wire to the light. I've wrapped that wire on both ends with black tape to indicate that it is used as a hot wire. – Ryan D.W. Sep 2 '14 at 18:18
  • In that case, I think this image more accurately describes your situation. – Tester101 Sep 3 '14 at 12:35
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If one switch is overriding the other in a three-way circuit, that usually means one of the switches has been hooked up incorrectly. If you get the common and one of the travellers exchanged, you will see exactly this behavior.

Double-check each switch to make sure you know which contacts are the common and the two selectable terminals, and double-check that the latter two are the ones hooked to the travellers.

(This is not an uncommon error.)

  • 2
    Thanks. In the end, this was essentially correct. I made the mistake of initially assuming that the wires would be the same color on each end (e.g., red to red). I cannot see the entire run of wire to confirm that, though, and the assumption turned out to be incorrect. What I ultimately did was identify the two traveler wires by checking for continuity by disconnecting everything and using a multimeter and an extension cord that I ran between the two switches. Once I unequivocally confirmed those two (which did change colors), I was able to rewire it to work properly. – Ryan D.W. Sep 7 '14 at 16:49

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