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I have a situation that I can't find any information for online. A couple quirky things going on that I can't figure out. Unfortunately, I have the switches out and the wires separated.

  1. I have three bathrooms each with one multiway switch. Each multiway switch controls a light in that bathroom as well as a central exhaust fan.

  2. All of the previous switches were 4-way switches. I know it's possible to use a 4-way as a 3-way but I don't know if it's necessary because of my central fan/individual light situation.

  3. There are 4 wires going to the switches in each box, two of them are always hot, one seems to be a common or traveler for the fan, and the last seems to be the common for the bathroom light.

I really hope someone can help explain to me how I should wire my switches!

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    Pictures of the wiring would be extremely helpful.
    – FreeMan
    Jan 3, 2022 at 16:40
  • 2
    Can you explain how this used to work? Especially what would happen with the fan if multiple bathrooms were being used. Jan 3, 2022 at 16:45
  • @FreeMan. I'll try to put up some pictures but since the switches are out, you'll only see the disconnected wires with my labels. How this used to work is when everything is off, and you flip a switch in one of the bathrooms, the central fan and local light would go on. If someone else then flipped a switch in another bathroom, that light would go on and the fan would remain on. Basically, any light on in any bathroom would turn on the fan. All lights would have to be off for the central fan to turn off.
    – JKK
    Jan 3, 2022 at 17:21
  • Those aren't 4-way switches. They are DPST / 2-pole switches, which are a real oddball. If aesthetics are your motivation, you will probably find they are not made in every style. Normally. the only documentation of what the wires do, is in how they are connected currently. Jan 3, 2022 at 18:44

2 Answers 2

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The fact that you're replacing all of them at once suggests to me that you're doing it for aesthetic reasons.

These switches are not 4-ways - they are a special and rare type called 2-pole or DPST. As such, the "aesthetics" plan probably isn't going to work out - you are unlikely to find a 2-pole in a matching style.

You may be better off changing this over to tandem switches. They are available in a variety of aesthetic forms.

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They wire exactly the same as a 2-pole switch, after you take one special step. They ship with one side "ganged" assuming 1 hot wire will supply both devices. You need to follow their instructions to "break off the tab" or separate that side. Failing to do this will probably trip a breaker in your house.

The downside (or upside, depending on how you look at it, is the user is obliged (able) to control fan and light separately.

I personally find "ganged light and fan" to be a grating annoyance: for simple affairs, and personal grooming, I don't need the fan at all. But for more serious affairs, I need the fan much longer than I need the light. Maybe it's just me.

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  • Excellent. Thank you everyone for your help! Problem solved!
    – JKK
    Jan 3, 2022 at 19:07
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Grab an ohm meter/continuity checker and test those switches. You say they're 4-way .... but suppose instead they may be dual-pole switches. The outward appearance of both types is identical but the electrical function is different. Connect one lead to one of the black-colored screws; connect the other lead to the gold-colored screw on the same side. Confirm continuity between the two terminals -- toggle the switch to its alternate position if necessary.

Next, toggle the switch to interrupt continuity. This next test reveals whether the device is 4-way or dual-pole: check for continuity between the original black-color screw and the gold-color screw on the opposite side. If there's continuity then the device truly is a 4-way switch. If not, then it's actually a dual-pole device.

A dual pole switch is functionally the same as two ordinary isolated ("single-pole") light switches ganged together so that a single toggle operates them both.

It's easy to see how to wire a dual-pole switch to do the function you need. The hot corresponding to the fan circuit goes on one of the black-colored screws; the traveler for the fan goes on the gold-colored screw on the same side. The hot for the light circuit goes on the other black-colored screw on the other side; its corresponding switch leg goes on the gold-colored screw also on that side.

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  • Wow Greg. You were right! They appear to be dual pole switches. Was not expecting that. Flipping the switch connects and interrupts each side independently.
    – JKK
    Jan 3, 2022 at 18:57
  • Question, is a dual pole switch the same thing as two single pole switches? Seems like they would be functionally identical. I might just get some double switches and separate out the functions.
    – JKK
    Jan 3, 2022 at 19:06

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