Get matched with top electricians in Littleton, NC

A C-wire connects your thermostat to your household heating and cooling system to provide continuous 24V power. The furnace's transformer converts household electrical current into this low-voltage power to operate the HVAC system's circuitry. In most configurations, the C-wire connects to the terminals labeled "C" on both the furnace's low-voltage terminal block and the thermostat. In some cases, if a dedicated C terminal is unavailable, the C-wire can be connected to the "G" (fan) terminal at the furnace.

Most electric water heaters have a built-in shut-off switch, so you can simply turn that to the OFF position. Some water heaters have the switch inside a panel, so you might need to unscrew the panel, remove it, move aside the insulation, and then shut the water heater off. To make sure it’s off, you can also locate the switch for your water heater in your electrical panel and shut the power off there. Most electrical panels have dedicated switches for the water heater, so you can shut off the power without affecting the rest of your home.

A C-wire is typically blue, but don’t rely on colors to find which wire is which when it comes to thermostat wires. The C-wire may also be black, brown, or purple. Instead, if you’re looking for the C-wire, look at the thermostat panel for a wire connecting to “terminal C,” or call in a pro to help you look for a C-wire.

If you’re interested in exploring other avenues to completely upgrade your electrical panel, it’s also possible to add a sub-panel, which is a smaller panel that connects to what you currently have in place. This way, you can add additional circuits without having to swap out your main panel.