Anatomy of a 4-Way Switch

4-way switches are really simple, they look difficult because the switches have no indication how they work inside.

Here is a typical 3-Way switch setup:

As shown the light is off because the dimmer outputs on the “load” terminal and the light through the 3-way is connected to the “traveler” terminal.

The paddle position determines which output is connected. This applies to both the dimmer and the 3-Way (or 4-Way)

If you change either the dimmer to output on the traveler or change the 3-way to connect to the load wire the light will go on.

Essentially either device will switch which wire they connect to (black or red).

So to make a 4-Way you simply put a different type of switch in between the existing that will reverse the black and red wires. Like so.

Showing individual 4-way positions:

I hope this is helpful.

John

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I have long thought it would make more sense to refer to the two load-carrying wires as “loadA” and “loadB”. The so-called traveler wire does not differ in any way from the “load” wire - - - other than its ability to confuse!

The “traveler” is a terminal used by the electrical trade. Its not likely to change and I’m not sure it should. Electricians have to deal with many more configurations that just a dimmer and a bulb.

Now if I read instructions that included loadA and loadB I’d be off looking for the 2nd load.

Its really really difficult to make any instructions be interpreted exactly the same by everyone.

Especially since sometimes the traveller is special, and not just another “load” conductor. For example with “auxiliary” switches that we discuss occasionally in these forums, or Lutron Maestro “companion” switches (the same idea, but predate our smart switches by many years), the traveller does carry some voltage, but not enough to power the load – instead it is used for communication.