Thermostat cables, while not the most complicated cables ever constructed, are used in every household, commercial, and industrial application. They are the communication link between a heating or cooling apparatus and its control mechanism. Thermostat Wire is a class 2 power-limited circuit cable for use in thermostat control applications. Thermostat wire goes from your heat system to your thermostat. Thermostat wire and cable is used for signal systems, intercom, burglar syatems, remote control and heating and air conditioning in 18 and 20 awg sizes. It is made with a similar number of strands that thermostats have and perfect amount of thickness. These cables are also used in alarm systems, intercom systems, and other low voltage installations. Thermostat cable is constructed with solid bare copper conductors, PVC insulation, and a PVC jacket.