# How 4-way switch circuits work -- frame by frame

Below are a sequence of images illustrating the function of a circuit using three switches to control a light. The page is intended as an adjunct to 4-Way Switches -- an animation. View that page first.

The center switch is 4-way switch, while the outer two switches are 3-way. This page is just intended as an aid in case you want to view the sequence of images more slowly.

For a discussion of how to wire such circuits, see 3-way and 4-way light switches. That page discusses proper wire colors and several ways to wire a multiswitch circuit..

Note that in the stills below, the wires are color coded to indicate their voltage state:

• Red wires are hot (120 volts),
• green wires are neutral (0 volts), and
• blue wires are connected to neither 120 volts nor neutral (floating).

For the lamp to turn on, we need a hot (red) wire to reach all the way from the voltage source on the left to the lamp on the right. For the lamp to burn, the switches must be configured to provide a complete circuit from the voltage source on the left to the lamp. Routing the voltage to a dead end means the lamp will be off.

The captions will make the most sense if you realize that these are frames of the movie at 4 Way Switches - an animation. I would annotate differently if I were doing these still images from scratch.

Send comments and suggestions to matthews@wfu.edu.