A companion switch, also known as an auxiliary or remote switch, is a secondary switch used in multi-location lighting control systems, such as 3-way or 4-way switch setups. It allows users to control a single light or group of lights from multiple locations. This is particularly useful in large rooms, hallways, or staircases where controlling the lighting from different points is convenient.
In a typical 3-way switch setup, two switches control the same light fixture. A companion switch works in conjunction with a master switch, which is the primary switch that directly controls the light. The companion switch communicates with the master switch to turn the light on or off, or to adjust its brightness if dimming is supported.
The operation of a companion switch depends on the type of system used:
1. **Wired Systems**: In traditional wired systems, the companion switch is connected to the master switch via traveler wires. These wires allow the switches to send signals back and forth, enabling the light to be controlled from either location.
2. **Wireless Systems**: In modern smart home setups, companion switches can be wireless. They communicate with the master switch or a central hub using radio frequency (RF), Wi-Fi, or other wireless protocols. This eliminates the need for traveler wires and simplifies installation.
Companion switches are often used in smart lighting systems, where they can be part of a network that includes dimmers, timers, and sensors. They provide flexibility and convenience, allowing users to control lighting from various points in a home or building, enhancing both functionality and energy efficiency.