3-Way Light Switch Wiring

Free graphic


You even got this right, Randy:

Parts of a Three - Way Switch

The two lighter, brass-colored screws are called the traveler screws . … The last screw is the common terminal. It is a darker color than the travelers , usually dark brass, copper, or black .

Nice graphic…as usual!


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Thanks again, Randy. :slight_smile:

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Nice graphic, but that is not the only way to wire 3 ways. Also the cable does not need to be #12.

True, but that’s the simplest form for most to understand how it works. Feed to one switch travelers in between and switch leg to the light. It’s a nice graphic. :sunglasses: Randy made some choices in designing it that way. This is probably the most likely scenario you’ll find in a house. If it were for a commercial project you might be able to do things like eliminate the EGC to the switch if metal boxes are used.

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and metal conduit?

Not necessarily, NM cable to a metal box would require that the box be connected to the EGC in the NM cable. The switch would not require a bonding jumper or direct connection to the bare EGC. The two 6-32 mounting screws would be sufficient for bonding the switch to the grounded metal box.

The bonding jumper, I got you :slight_smile: I thought you meant eliminate the bare EGC part of the NM cable.
The same can be done inside a residential dwelling. I personally prefer metal boxes than the cheapo plastics. To me, the plastic boxes (blue ones) are very flimsy unless they are fiberglass, but even then. Build once, build right.

I find mis-wired 3-ways six to ten times a year. I might find more if I was more faithful strolling up and down stairs and halls trying all the switch combinations. Oddly, I rarely find a mis-wired 4-way. I think it may be because the electricians are really paying close attention on those.

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That’s correct, I was referring to the EGC to the switch in Randy’s graphic. I agree with you on the junky plastic boxes.