Three-Way Switch
A wiring configuration that controls one light from two different switch locations — common for hallways, staircases, and rooms with multiple entrances.
A three-way switch lets you control the same light from two locations — flip the switch at either end of a hallway and the light toggles on or off. The name "three-way" refers to the three terminal screws on the switch (common, and two travelers), not the number of switches or locations.
The wiring works by sending power through one of two traveler wires between the switches. When both switches connect to the same traveler, the circuit is complete and the light turns on. When they connect to different travelers, the circuit is broken. This is why a three-way switch doesn't have "on" and "off" positions marked — either position could be on or off depending on the other switch's position.
Smart three-way switches add a layer of complexity. Most require one smart switch at one location and a companion switch (or the original dumb switch) at the other. Lutron's system uses a wireless Pico remote as the companion, avoiding special wiring entirely. Always check whether the smart switch you're buying supports three-way installation — not all do.
Specifications
| Switches needed | 2 three-way switches |
| Wires | Uses traveler wires between switches |
| Four-way | Add a 4-way switch for 3+ locations |
Related Terms
- Neutral Wire
The return path for electrical current in a circuit (usually the white wire in US wiring). Many smart switches require a neutral wire — older homes often don't have one in the switch box.