4 way switch wiring . A 4-way switch should really be called a 4-terminal switch. A 4-way switch is used when a light, a group of lights, or other load must be controlled from more than two switching points.
A 4-way switch is similar to a 3-way switch in that it does not have On and Off positions. A 4-way switch is always connected between two 3-way witches. Three-way switches are connected to the source and to the load.
A 4 way switch wiring consists of three or more switches to control the same light. The system is often used in staircases to control the lighting at three different levels and in rooms with several entry points. The set-up consists of two 3-way switches and one or more 4-way switches (see illustration below). Notice that the switches do not control the neutral wire.
The schematic drawing below illustrates how the contact points within the switches can route the electricity to the light fixture