Wiring 4-way Light Switches


Old 01-28-02, 03:42 PM
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Question Wiring 4-way Light Switches

I'm troubleshooting and re-installing a 4-way light switch in an older home (circa 1920). It uses the old cloth-and-rubber wrapped 2-wire system in flexible steel BMX conduit, or in some places knob-and-tube.

Problem: One light fixture is controlled by switches from 3 different locations: (2) 3-way switches, and (1) 4-way switch. I've located the hot wires and the 2 travelers in both of the 3-way switch boxes. But, when using a continuity tester in the 4-way switch box, I get completed circuits from ANY two wires I touch!?! Also, one of the 3-way switches must always be in the "on" position for the other 2 switches to work.

Question: is there a simple fool-proof method for wiring and troubleshooting 4-way switches, similar to the one I use for installing 3-way switches (see below)?

3-way Light Switch Wiring Method

To install and troubleshoot for proper wiring between (2) 3-way switches (without a continual circuit or ground fault), I've always used the following method:

1. disconnect all 3 wires from both switches
2. with the circuit hot, use a light probe to find the hot wire (common) in one switch box; shut off power
3. attach the hot wire to the single screw (common terminal) for that switch
4. wrap the other two wires in that box (travelers) together
5. use a continuity tester to find a complete circuit among the 3 wires in the second switch box (they'll be the other ends of the travelers from the first box)
6. attach both sets of travelers to the 2 screws opposite each other on each switch
7. attach the remaining wire for the second switch (hot wire) to the single screw (common terminal) of that switch
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Old 01-28-02, 06:13 PM
Join Date: Sep 2000
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Did you just ask and answer your own question? Do you still need help? I'm confused.
Old 01-28-02, 07:16 PM
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Look at the diagram attached for the concept, then test away.

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