Convert a 3-way light switch to a single-pole switch?

May 15, 2011 2:14 PM

How do I convert a 3-way light switch to a single-pole switch?

Our hallway has a light at one end and a ceiling fan at the other. There are three switches in the hall that control both the light and the fan. Here's a quick-and-dirty diagram.

I want to use the light independently of the ceiling fan, and assume I need to remove the 3-way switch labeled A and replace it with a single-pole switch.

Here's a photo of the wiring to Switch A. (And a higher-res version.) How do I connect the single-pole switch (which has two holes) with the three wires I have?

I'm new to DIY home electrical, but I've successfully replaced a dimmer switch and added a timer switch to the bathroom fan. Google searches for doing this conversion have left me confused, and I'm hoping the good folks of MeFi can explain it to me in a way that won't lead me to kill myself and/or burn the house down. Thank you!

posted by DakotaPaul to home & garden (8 answers total)

Perhaps an electrician will correct me, but it doesn't sound like what you want to do is possible without running a new set of wires from one switch to the light and then rewiring the fan completely.

The light and fan are wired together in series and they need to be wired in parallel for your setup to work. Essentially, the fan and light are currently on the same series circuit and must be placed on their own branch of a parallel circuit. This is probably where I'd call in an electrician to do the job for you.

That said, I'm not an electrician.
posted by jz at 2:28 PM on May 15, 2011

That is actually a 4 way switch. This is the point where i would suggest hiring an electrician. You need to run a new wires and rewire/replace the remaining switches.
posted by ihadapony at 2:38 PM on May 15, 2011

Thanks, jz and ihadapony. If it matters, I just looked at Switch B, which as four wires and nothing labled on the switch. So I'm definitely out of my league and I think I'll take your advice.
posted by DakotaPaul at 2:41 PM on May 15, 2011

The light and fan are wired together in series

This is unlikely, but they are both on the same run of wiring, so without getting into the ceiling and adding wire there's no way¹ to control them independently— there's only one set of wires going up there, and the power to that set of wires can only be on or off.

¹ Well, I can think of some ways but hiring an electrician is probably a better idea than any of them
posted by hattifattener at 5:21 PM on May 15, 2011

An electrician can re-use the wires you have already, Your two that you want as three ways will need one less wire and the 4th, extra wire can be used just for your single switch to the light.
It's not as confusing as people are making out, and pretty easy for an electrician.
posted by lee at 5:38 PM on May 15, 2011 [1 favorite]

If the light and fan are on the same run, and all the switches are up-circuit of those, you're pretty much going to have to run wire.

The real problem is figuring out which wire runs where. If you felt bold and in a DIY mood and had a volt meter and a continuity tester and nothing you needed for the next day or so was on that circuit and knew how to make sure everything was really powered down so that if the people who lived there before had somehow spliced a wire from a totally different circuit into that circuit to run the fan but not the fan light (don't ask me how I know this is even a possibility!) you would know it, then you could spend some time and map things out.

If everything I just said doesn't make perfect sense and sound like fun, you will be much happier just hiring an electrician for this.
posted by Kid Charlemagne at 5:48 PM on May 15, 2011

Without having a wiring diagram of the switching circuit (IE: I'd have to know what wires go where at each of the three switches and the ceiling fan) you can't tell for sure but it is likely that you can't do this with existing wire. If you have two switch legs going to the light then it would be easy but considering you already don't have a seperate switch for the fan it is unlikely your set up has independent switch legs.

What you could do however is use an intelligent switch to control the light and fan. Lutron for example makes this wireless remote switch.
posted by Mitheral at 7:45 AM on May 16, 2011

Thanks, all, for the additional info!
posted by DakotaPaul at 11:57 AM on May 16, 2011