Low voltage cable with insulated solid conductors and jacket resistant to spread of fire. Used in thermostats, heating and air conditioning installations, burglar alarms, intercom systems, and door bells. Type CL2, 300-volt rating. Brown. UL (Underwriter's Laboratories) listed. This 18/3 cable (often having red, white, and green or blue wires) is ideal for 24-volt heating and cooling systems requiring a common wire, or for boilers and water heaters.