I am trying to replace a switch that had a 4 position light knob and a 4 position fan knob. The old one had three wires coming out of it and the new one has 4. Below is a picture of my wall and the new switch: enter image description here

And here are the instructions:

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Is there a way that I can properly wire this switch or do I need to return it and buy a different type? If I need to get a different one, what should I look for?

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    Do you know which of the load wires goes to the light and which goes to the fan? – ThreePhaseEel Jan 10 at 1:51
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    Looking at the switch: black gets incoming power. Red to fan. Yellow to light. Green where it goes (if you don't know where that is, hire this job out). – Mazura Jan 10 at 2:47
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    What extra wire? That bare one? .... yeah, time to hire someone. – Mazura Jan 10 at 2:49
  • @Mazura - the bare wire was in the box but no hooked to anything. I've heard that bare copper wires are grounds so that's what I assume it is but I'm not sure why they would have two different types of grounds in there. It's possible the bare wire isn't hooked to anything. – Brh Jan 10 at 14:39
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    Yeah my "black and white" quip wasn't so far off the mark. Colors mean less than you would hope for in mains wiring. Any hot is allowed to be any color but green (whaaa? Hots can be white!? Yeah...) You have to look at functional roles and/or measure or test. Fortunately this one is easy, we know the /3 goes to the fan/light since separate control requires 3 wires. – Harper - Reinstate Monica Jan 10 at 16:55

Everywhere in the world, green, green/yellow or bare colors are reserved for ground. The only exceptions are the former Soviet Bloc, and they now have harmonized to this rule too. So that is as simple as that. Grounds are never used to flow current normally, and only come up in fault conditions when it is time to save your bacon. So from a logical, "how does this circuit work perspective, they are disregarded. I never show them in diagrams, but they are always there.

Your old controller controlled the fan and light separately, so it plainly had 3 wires because that is the bare minimum needed to do that. Your new one has 3 wires (from a functional perspective). Therefore, this is easy. Go to it!

If you are unclear which cable is supply, most likely if one cable is 2-wire (black/white) and the other cable is 3-wire (red too) then the 3-wire must necessarily be the one going to the fan, and the 2-wire goes to supply.

  • Wait! The new one has 4 wires.... right? Three hot and one that hooks to the ground. The previous had 3 wires - two hot and a ground. If you are saying one fewer because you don't count grounds then there is still a one wire difference between the switches. That's where my confusion comes from. – Brh Jan 10 at 17:11
  • That is impossible unless the old fan controller had some proprietary control scheme that controlled both fan and light on one wire, which would then indicate a control module up in the fan that is a matched set to the old switch. We need to know a lot more about the old controller. Can you get a model number? – Harper - Reinstate Monica Jan 10 at 17:15
  • I actually have the old controller hooked back up since I was having trouble with the new one. I don't have a model number, but could snap a picture if it would help? The old one has three wires coming out of it: black, yellow and green. The black/yellow are hooked to the black wires in the wall, the green hooked to the ground and the bare wire from the wall is not attached to anything. Let me know if I should post a picture of it – Brh Jan 10 at 17:26
  • wait, what does the red wire do with the old controller? Does it change the fan speed and dim the lights at the same time or are they separately controlled? – Harper - Reinstate Monica Jan 10 at 18:30
  • Well there's no red wire on the old controller. That's where the confusion comes in - there are 4 wires on the new controller and 3 on the old one. On the old one the fan and the light are controlled separately. The yellow wire controls the light and the black controls the fan. – Brh Jan 10 at 19:33

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