5401 WIRE, 18/3 THERMOSTAT 500' | Conductor 18 AWG soft annealed solid copper per ASTM B3-90. PVC thermostatic insulation, temperature 60 deg C. Used for thermostat controls, heating and air conditioning installations, burglar alarm systems, intercom systems and doorbells. Type CL2, 150 V. PVC insulation UL13 for power limited circuit cable for other than plenum, riser or tray uses and UL1581 approved.