I am trying to replace my bathroom fan switch with one having a humidity sensor (Leviton DHS05: https://www.leviton.com/en/products/dhs05-1lw).

The existing switch (see photos) is connected to a yellow/white wire, a red wire and a green wire. Three more wires are currently sitting unused in the box: a black, a blue and what seems to be a pink one.

I was thinking Green is ground and Red must be load. I would have said the white cable is neutral, but the "yellow" label of the old switch makes me confused. Then I'd have connected the black wire currently sitting at the back of the box to the line, leaving blue and pink unused.

Would you say my assumptions are correct? I'm in Canada so wire colors should be the same in the USA. Thank you!

Switch currently installed Back of the switch New switch wiring

  • what is in there now? ... it looks like a dedicated wired remote control for the fan
    – jsotola
    Commented Dec 10, 2023 at 1:28
  • The pictures show the current installation that's a fan timer switch: i.imgur.com/QBEZiGi.jpg
    – haoxp
    Commented Dec 10, 2023 at 2:07
  • What make and model is your bath fan? Commented Dec 10, 2023 at 4:10

1 Answer 1


Wire colors matter, somewhat. But what really matters is what they are connected to.

A device in the US saying Yellow, Red, Green is extremely unusual. Any typical switch, control, etc. designed for direct control of the usual 120V power supply will almost universally label things as:

  • Hot/Line/Supply/Incoming Power = Black
  • Neutral = White
  • Ground = Green or bare
  • Switched Hot/Load/Outgoing Power = Black, red or blue

Code generally only requires "Neutral = White" and "Ground = Green or bare", with just about everything else being use for any variant of Hot or Switched Hot.

Seeing a reference to Yellow is extremely unusual. Not that a yellow wire would necessarily be unusual, but it would normally be used in place of black or red or blue. See, for example, Harper's typical 3-way switch diagrams using yellow for travelers.

That makes me think the colors are specific to a particular wiring scheme between this timer and the fan unit in the ceiling. Similar to typical low-voltage thermostat wiring. In this case, it looks like the wiring is closer to 14 AWG than typical thermostat wiring, but the colors and the color coding is reminiscent of that. That means any answers as to the meaning of the already connected 3 wires is purely a guess.

Very likely the answer lies with the fan itself. You may need to remove it from the ceiling, or at least partly remove it, in order to find a make/model # to figure out what the wires mean. If they are actually working on a low-voltage setup (like a thermostat) then an off-the-shelf humidity sensor designed for 120V will not work, except for something designed by or for the manufacture of the fan.

If they actually work on 120V then it may be possible to install an off-the-shelf humidity sensor, but no way to guess how the wiring would be set up.

Update: Googling the part number on the timer references Lifebreath and OP has commented that it is a Lifebreath product. Lifebreath appears to offer controls that include humidistats, so that is likely the best solution provided OP's current fan is compatible.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.