How Does a Three-Way Switch Work?

Three-way switches are useful in large rooms, hallways or staircases where a light can be controlled from multiple positions. For instance, a three-way switch can control a light in a stairwell from both the top and bottom positions on the stairs.

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How Does a Three-Way Switch Work?

Why would you need a three-way switch?

How does the switch work?

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A Three-Way Switching Circuit

A three-way switch is part of a circuit involving an electrical fixture, be it a light or fan, and two switches. The switch itself has four posts to connect wires. One is for the ground wire, and one is for the electrical current. The other two are for control, or traveler, wires. One wire provides current to the fixture. The other wire works in conjunction with the second switch to control whether the light can be turned on or off.

How do you wire a fixture for three-way control?

The basic design of the three-way circuit is that one traveler wires connect to each switch and the other traveler links to the fixture. Each switch must be grounded and only one switch needs a wire carrying a current. The second switch does not need a current and can be tied off to the box.