I have a wall switch that controls a whole house fan. I am trying to replace it with a ZEN75 800LR heavy duty wall switch.
I am not good with electrical stuff so I’m sorry if I am saying something wrong.
In normal setups I think there are 3 wires coming from the junction box (ground, neutral, power) and 3 wires coming from the end device (the fan in my case). And a switch sits in the middle.
My setup is a bit different.
There are 3 wires coming from the junction box (ground, neutral, and power)
But there is only 1 wire coming from the fan
In the current dumb switch, flipping the switch connects the power wire coming from the junction box to the 1 wire coming from the fan. This turns the fan on.
I cannot figure out how to wire this up with the ZEN75 800LR.
That is interesting. Would you mind posting a picture of the switch box and all the wires? Curious about the one wire to the fan. A closeup of where that wire comes into your switchbox may yield some clues.
Ok! Note what I’m saying here is an educated guess, so please verify this before taking any action.
Based on that picture and explanation, I’m thinking you have a loop switch (between the red and black - one is the hot wire and the other is the return path to the fan. The white wire that isn’t connected, would need to be connected to the neutral at the other end (if possible) in order for the ZEN75 to work; since it needs a neutral. Be sure it is attached to the neutral for the fan circuit and not stolen from some other circuit.
You’d then need to use a multimeter to determine if the black or red wire was the hot (line) wire. The other would be your fan (load) wire.
However you may have another challenge. Since that wire is yellow, it is #12 wire, which may indicate that this is a 20A circuit. You would want to double-check the load the fan generates to make sure it won’t overload the ZEN75. (Which I believe is rated for 15A, or 1 HP fan at 120v… see this for details ZEN75 Heavy Duty Switch: Recommended Loads - Zooz Support Center)
Also were those ground wires (the bare ones) connected together across the two circuits (yellow and white Romex)? If not, that may be a clue about some previous ‘diy’ electrical going on here, and you may want an electrician to look at this closer… ymmv. and of course, I’m reading tea leaves at this point so I could be wrong.
Getoffmylawn raises a good point about the yellow romex… First step should be confirming whether or not that’s a 20-amp circuit, what the fan’s specs are, and then check to see if the Z75 can handle whatever that overall answer is.
If you confirm the z75 can work, then the next big hurdle will be getting down there neutral for it… But there’s no point putting brain cells against that until you confirm if the Z75 can handle that particular circuit and the fan itself.
