What is the blue wire on a ceiling fan? Ceiling Fan Wiring Explained


When it’s time to wire a new ceiling fan many owners are confused by the single blue wire that doesn’t seem to match up with any of their existing ceiling wiring. Where does it connect? And what does it do? In this guide we will explain the function of the blue ceiling fan wire as well as some ceiling fan wiring basics.

Important: If you are unfamiliar with electrical work or uncomfortable wiring a ceiling fan yourself, please contact an electrician.

What is the blue wire on a ceiling fan?

The blue wire on a ceiling fan is to control the power running to the light kit. The black wire is usually reserved for fan power only and does not extend over to your light kit. Without connecting the blue wire on your ceiling fan to a power source, you will not be able to control your lights.

A lot of confusion comes from the fact that blue is not a standard wall wiring color and therefore has no same-color match like your black and white wires. Why is this wire blue? Simply to distinguish it from the black wire that controls the fan. 


Where does the blue wire go on a ceiling fan?

The placement of the blue wire depends on whether you plan on having your ceiling fan controlled by one or two switches.  For single switch ceiling fans, you’ll be sharing the switch with the black ceiling fan wire. When connecting your ceiling fan to two separate wall switches, both the blue and black ceiling fan wires are connected to their own separate switches. 

Below we have a diagram for both scenarios along with a general wiring guide. Again, if you are unfamiliar with electric wiring than we encourage you to contact an electrician. Since ceiling fan wiring may vary by brand and model we highly recommend you refer your specific ceiling fan manual before installation. 

single Switch Ceiling Fan Wiring

Follow the diagram below if you have access to only a single wall switch when installing your ceiling fan. Note that the blue wire is connected to the black fan wire so that they can both be operated by the same switch.

  • Connect the ceiling fan blue wire to both the black fan wire and the black wire from the ceiling. This connection allows both the ceiling fan and light kit to be powered by a single light switch.
  • Grounding wires are to be connected together. These wires are commonly green, yellow or bare copper.
  • Finally, the white wires from the ceiling and fan are connected together

Dual Switch Ceiling Fan Wiring

A duel switch setup allows you to control the light and fan power on separate switches. Unlike the single switch wiring setup above, the blue wire on a ceiling fan is connected to it’s own power switch instead of having to share a switch. The basic idea is that each switch feeds either the black wire for the fan power or blue wire from the light kit.

  • Connect the black ungrounded wire from the ceiling to the black wire from the fan. This connection will allow you to control the fan power from the first switch.
  • The blue wire from the ceiling fan gets connected to the second live wire from the ceiling. This second wire can vary in color but is most commonly red or black. This connection allows you to power your lights from the second switch. 
  • Connect the white grounded wire from the ceiling to the white wire from the fan.
  • Lastly, make sure all grounding wires from the ceiling fan and ceiling are connected together. You will usually see 3 grounding wires that may vary in color. The most common grounding wire colors are green, yellow and bare copper.