I decided to be handy and change all of my receptacles in the house. Everything went well until the garage. There are 3 light switches in the garage that go to 1 light source that has me stumped. Two light switches are 3-ways and one is a 4-way switch. I messed something up because the 4-way has to be in the on position in order for the 2 other switches to work. The 4-way has 2 black and 2 purple wires, while the 3-ways are all black because it is 1950"s wiring. Thoughts?

  • You made a common error: not marking every wire and verifying the internal connections on the 4-way before removing :-( . Here's where a "beeper" or equivalent can help: turn off mains power, flip a 3-way to see which of the wires to the 4-way are connected, and so on. Handy diagram here: do-it-yourself-help.com/wiring_diagrams_3_way_multiple.html Mar 29 '16 at 12:17

Just to clarify, the travelers on a 4 way are connected to the top terminals from one three way and the bottom terminals from the other.

NOT from side to side.

Google 4 way switch and check the wiring diagrams against what you have done. Like here.

Good luck!

  • Thank you for your note. How do I find out which wires go in the common and traveler screws?
    – Theresa
    Mar 29 '16 at 17:57
  • On the three-way switches, the common screw is by itself at one end of the switch, and it either gets the hot wire feed or the switched wire that goes to the light depending on which end of the circuit it is on. The two terminals at the other end of the switch get the travelers. Study the drawing that on the page I linked to. It should help.
    – ArchonOSX
    Mar 29 '16 at 19:01

A 4 way just switches the travelers from a 3 way, if one leg is wrong on the 4 way or one of the 3 ways is wrong, not working in all the positions is common. To help figure out where the problem is a list to all 3 switches in each position will be needed.

  • Hi Ed, Thanks for responding. I've attached a photo. I don't know which wires go to which screws. Initially, I put all the wires back in the same spot when I had installed the new switches, but the light didn't turn on for any of the switches. So, flipped the 2 wires on the left sides of the 3 ways and now the 4-way has to be in the on position in order for the 2 other switches to work. Light image: dl.dropboxusercontent.com/u/36322699/light.jpg
    – Theresa
    Mar 29 '16 at 18:14

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