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I am replacing old switches & outlets in my 1970's home and encountered an issue with this 3 way switch. One side only works if the other is on. Both sides are only 2 wire with the white wire being hot. I'm pretty sure I reconnected them both as they were previously connected, but, like I said, the side with several wires[![enter image description here in/out of the box only works if the other side is "on". What happened and how can I fix it?

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  • I've updated the pictures to show both sides of both switches. Thanks for the help!
    – jaydensdad
    Commented Feb 6 at 20:17
  • Aside: In the left halves of the photographs it appears that the blurry black wires at the bottom are wrapped anti-clockwise around the screws. For simple screw connections the wires must always be wrapped clockwise so that tightening the screw does not loosen the wire. (Connections that clamp the wire(s) do not depend on directional wrapping.)
    – HABO
    Commented Feb 6 at 20:55

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If both really are two-way switches, wiring one of them "backwards" can produce exactly this behavior. Check that hot and the two travellers are attached to the correct terminals on both ends. (Easy mistake fore a novice to make, and since it's usable and said novices often have no idea how to fix it, it often gets left that way.)

If that is what's going on, this is a duplicate.


Quick sketch follows. I'm going to leave figuring out what each combination of switch settings does, in each circuit, as an exercise for the reader. Along with drawing, and characterizing, the case where both switches are hooked up wrong.

circuit diagram for the right way, and two wrong ways, to try to build a "3-way" switching circuit out of two SPDT switches

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  • Keshlam, thank you - I'm starting to wonder myself if it was ever wired correctly. Having said that, I'm not seeing a wiring diagram but would love to see what you're referring to.
    – jaydensdad
    Commented Feb 7 at 19:41
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A 3-way switch circuit with control from either switch (what is normally meant by "a 3-way switch circuit") requires 3-way switches (with 3 terminals and 3 wires connected) at both ends.

Using a two-terminal on/off switch at one end, the circuit will not be a 3-way switch in the standard sense.

And, indeed, despite your words, your pictures show two different switches, (as the boxes look different) each with 3 wires connected.

Likely you have mixed up which wire goes to the black screw on each switch. If you took before pictures of the working arrangement, that would help to sort it out now.

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