Electrical – Ceiling fan wiring blue/white/black vs. 3 black/3 white/red

ceiling-fanelectrical

I want to install a ceiling fan that has 3 wires – blue white and black, but the ceiling light has 3 black wires and 3 white wires and 1 red wire.

I'm confused because the 3 black wires are together and the 3 white wires are also together and the red wire is alone.

Best Answer

It sounds like the original configuration was for a switched light and now you want to install a combination fan/light. It is hard to say for sure without knowing the existing wiring. One possibility for the existing wiring is:

3 cables

  • Black/White - incoming black hot & white neutral
  • Black/White - outgoing black hot & white neutral to next device on the circuit
  • Black/White/Red - black hot & white neutral to switch and red switched hot coming from the switch

In this situation, the light fixture connected to red & white. The problem is that the fan/light needs two switched hots - one for the fan and one for the light. That requires an additional wire in the cable. That leaves you with four options:

  • Connect blue & black on the fan to red. Then the switch will operate the fan & light simultaneously.
  • Run a new cable with 4 conductors (hot, neutral, 2 switched hot) + ground. Fan and light will each connect to a different switched hot and you will need to install a double-switch for the fan & light.
  • Use a /3 cable like I think you already have "the old way". Before neutral was required in every switch box, the normal way to connect a fan/light was with a /3 cable, as I think you already have. But instead of connecting white to neutral, white would become one of the switched hots. So you could connect black to black bundle, white and red to black and blue on the fan/light, fan/light white to white bundle and then install a double-switch with black to hot and white & red to switched hots. However, I suspect it is not code compliant to take a switch box that already has neutral and remove the neutral.
  • Use a smart fan control switch as described here
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