Here are common uses for wire colors:Blue or Black – C – Common wire,may be unused by your existing thermostat..Red – R – 24VAC power from the furnace’s transformer.Red – Rc – 24VAC (dedicated to heat call).Red – Rc – 24VAC (dedicated to cooling call).Green – G – Fan... (more items) Thermostat C Wire: Everything you need to know about the “comm Is this answer helpful?Thanks!Give more feedbackThanks!How can it be improved?How can the answer be improved?Tell us howPeople also askWhat color is the common wire?What color is the common wire?The common wire is usually black and the travelers red. In any case,the traveler wires will usually be the same color to distinguish them from the common wire. In this circuit the source hot is at the common on the 3 way switch and 3-wire cable runs from there to the dimmer.3 Way Switch Wiring Diagrams - Do-it-yourself-helpSee all results for this questionWhat do electrical wire color codes mean?What do electrical wire color codes mean?What Do Electrical Wire Color Codes Mean?Black. Black electrical wire is used for power in all circuits.Red. Red electrical wire indicates the secondary live wires in a 220-volt circuit,..Blue and yellow. Yellow and blue electrical wires are also used to carry power..White and gray. White and gray indicate a neutral wire.What Do Electrical Wire Color Codes Mean? | Angie's ListSee all results for this questionWhat is C wire for thermostats?What is C wire for thermostats?Thermostat wire connects the thermostat to the air handler or furnaceallowing for communications between the two. Older wires will have only 2 or 4 strands but the 5 strand will provide that extra wire known as the c wire.The Thermostat C Wire - wifithermostatreviewsSee all results for this questionWhat is a wire C?What is a wire C?The c-wireis an extra wirethat can be used to provide continuous 24V power to any application. It’s normally used to provide power for the thermostat. The “c” stands for common. It is often labeled as “c” on thermostat backplates. Keep in mind that it is not necessarily labeled as cand the wireis not necessarily any particular color.Thermostat C Wire: What It Is And Why You Want OneSee all results for this question Thermostat C Wire: Everything you need to know about the Oct 25, 2014Here are common uses for wire colors: Blue or Black – C – Common wire, may be unused by your existing thermostat. Enables continuous power flow from the Red wire. Red – R – 24VAC power from the furnace’s transformer. Red – Rc – 24VAC (dedicated to heat call). Red – Rc Emerson Sensi · Ecobee3 · Nest Wiring Color Codes | Color Codes | Electronics Textbook wwwboutcircuits››Vol. V - Reference›Color CodesChapter 2 - Color Codes. US DC power: The US National Electrical Code (for both AC and DC) mandates that the grounded neutral conductor of a power system be white or grey. The protective ground must be bare, green or green-yellow striped. Hot (active) wires may be any other colors except these.