How 4-way switches work -- an animation
Shown above is an animation of a circuit using three switches to control a light. The center switch is 4-way switch, while the outer two switches are 3-way.
For a discussion of how to wire such circuits, see 3-way and 4-way light switches. That page and its links also discuss proper wire colors and several wiring alternatives.
Note that in the above animation, 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.
You may view the above animation frame by frame at How 4-way switches work -- frame by frame.
Send comments and suggestions to matthews@wfu.edu.
- Back to 3-way and 4-way light switches. Start here for practical circuits with different arrangments of switches and lights, including proper color codes.
- My 4-way switches don't work. Use this if you began repairing and replacing a 4-way switch circuit and ran into problems.
- My 3-way switches don't work. A similar page for 3-way switch circuits.
- Miscellaneous tips and info. A collection of many of my help pages.
- Rick Matthews. My home page.