
10/13/2025
This circuit diagram illustrates a four-way switch setup, also known as an intermediate switching circuit. This is a common wiring configuration used to control a single light fixture from three or more different locations.
How It Works
The power source (P) and neutral (N) lines connect to the circuit.
The two outer switches are 3-way switches. They each have three terminals and are used to direct the current to one of two paths.
The two inner switches are 4-way switches. They have four terminals and are used to "cross over" the wires, reversing the direction of the current flow between the two 3-way switches.
The purpose of this setup is to allow any of the four switches to turn the light on or off, regardless of the position of the other switches. This is useful for long hallways, staircases, or large rooms with multiple entrances.
The circuit works by changing the path of the current. Each switch flips the flow of electricity, and as long as a complete path is formed from the power source to the light bulb, the bulb will be on. If the path is broken at any point, the bulb will be off.