I am installing a new Bathroom Fan/Light combo to replace an older unit. The new one comes with 5 connections - 2 black and 2 white (one of each labeled fan and light) plus a ground. My wiring has 4 wires - 1 black, 1 white, 1 red and a ground. Need some advice on how to wire this properly. Thanks in advance.

  • 1
    How was the old one wired? Do you have separate fan and light switches?
    – kicken
    Aug 4, 2019 at 17:38
  • 1
    Can you post photos of the insides of the boxes involved? Aug 4, 2019 at 17:42
  • How many switches are dedicated to the unit?
    – Kris
    Aug 4, 2019 at 18:18

3 Answers 3


The old one had a single neutral wire, which absolutely forced you to have fan and light on the same circuit.

The new one has 2 separate neutral wires, allowing you the option of putting fan and light on totally separate circuits. If you don't want to exercise the option, simply add both neutral wires to the place the old neutral was before.

As far as the blacks, one is hot for the fan, the other is hot for the light. Mark one of them with red tape, and wire it like the old unit. If this has now exchanged the switches, then put the red tape on the other black instead, and repeat.


A combination light and fan device uses two line conductors and one (shared) grounded neutral conductor. Each of the line conductors will be on a separate wall switch.

De-energize the circuit by switching off the circuit breaker or removing the branch circuit fuse.

The white is the neutral conductor. All neutral conductors are to be connected together. Connect the light & fan device's two white conductors to the white conductor in the ceiling wire.

The red and black wires are the switched line conductors. Connect either of these to one of the light or fan black wires. Connect the other of the red or black to the other light or fan black wire.

The bare copper or green (or green with a yellow stripe) wire is the grounding (often shortened to "ground") conductor. Connect all grounding conductors together.

Re-energize the circuit. If you find the switches control the opposite functions, de-energize the circuit and swap the connections for the red and black wires.

  • This did the trick. Everything is working perfectly. Thanks.
    – kcsanch
    Aug 5, 2019 at 18:38
  • Great! You did the hard work. Mind voting my answer up?
    – ndemarco
    Aug 5, 2019 at 22:11

I assume that you have two wall switches, one of which controls the light and one the fan, right?

To connect the unit in the ceiling:

  1. Connect the one white of the house wiring to the two white of the fixture in a single wire nut or screw connection if that is what there is. (The house neutral white will be the common neutral for both light and fan.)

  2. Connect the red to either one of the black wires and connect the black to the other black.

  3. Connect the ground wire to a ground screw or gnd wire, whichever there is.

You may find that the switch which formerly controlled the light now controls the fan and vice versa. If this bothers you, you could switch the connections of the red and black house wires.

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