A 120V thermostat switch is a device that is used to control the temperature of a room or space. It is typically connected to a heating or cooling system, and is designed to turn the system on and off in order to maintain a desired temperature. This type of thermostat switch is typically wired directly into the electrical system, and is usually rated for 120 volts. It is usually a single-pole, double-throw switch, meaning that it can be used to control two different circuits. The switch is typically connected to a temperature sensor, which will then trigger the switch to turn the heating or cooling system on or off depending on the temperature in the room. The switch can also be used to control fans, humidifiers, and other appliances that are connected to the same electrical system. A 120V thermostat switch is an essential component of any heating or cooling system, and is an important part of keeping a comfortable and safe environment.