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I have an idea how I would like to tackle some wiring I am about to do, but I am having trouble figuring out how to actually wire it all. I was hoping some of you could help me out.

Here's what I want:

I have 3 fixtures, Lights A, B and C.

I have 4 switches, Switches 1, 2, 3 and 4.

Switch 1 turns on/off lights A/B.

Switch 2 turns on/off lights A/B.

Switch 3 turns on/off light C.

Switch 4 turns on/off lights A/B/C.

Is this even possible to accomplish?

  • Switch 1 and 2 would be 3-way switches. Switch 3 would be a basic toggle. Switch 4 is a problem. I can't think of a way to make it do what you want. – Tester101 Oct 11 '14 at 2:10
  • @Quoid, do you want switch 4 to serve as an 'override' for switches 1-3, or do you want the inversion behavior described in my answer below? – ThreePhaseEel Oct 18 '14 at 20:59
  • @ThreePhaseEel I wanted the switch to behave like you said below, but I actually ended up wiring it a different way in the end – justinw Oct 20 '14 at 15:22
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This is possible using standard electrical wiring devices! You will need (in addition to standard electrician's tools and supplies):

  • Three three-way switches (switches 2, 3, and 4)
  • A four-way switch such as a Leviton CSB4-15T or equivalent (linking for the sake of those who have never bumped into one, a good home improvement store should have one kicking around somewhere) -- this will be switch 1
  • A two gang box for switch 4, with a switch + blank two gang faceplate -- one side of this faceplate has the standard switch slot, the other is blank.
  • And lots of 14/3 NM-B (in addition to 14/2) because you'll need to run multiple travelers

The wiring diagram is as follows: Hookup for three three-way and one four-way switch to achieve what the OP wants

Dotted lines are neutrals, the rest of the colors are self-explanatory. Three things:

  1. You will want to use a two-gang box for Switch 4, as the wire fill (eight wires) is too dense for a single gang. Perhaps you could stash a wiring diagram in there for the sake of anyone who has to fix it later, too?
  2. Keep your travelers consistent: in the diagram, red is up and black is down, always.
  3. Make sure the documentation for this is kept well, otherwise it will give the next electrician who encounters it a bit of a headache.
  • 1
    Switch 4 will turn on lights that are off, and turn off lights that are on. Either that or you are indeed a genius. – Mazura Oct 18 '14 at 5:58
  • You are right, it will behave that way. I suspect this is the closest one will come to what the OP wants using standard switches, though. – ThreePhaseEel Oct 18 '14 at 17:38
  • This was just too detailed of an answer to not comment on; I ended up wiring it all differently (ended up needing 5 lights on the breaker and only one 3 way) - but this is very valuable for future wiring projects – justinw Oct 20 '14 at 15:23
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There is no way to do this using standard wiring switches and circuits which meet NEC (electrical code). Two separate switched circuits would have to be bridged together. In an appliance or device, this functionality could be done with a double pole/double throw (DPDT) switch, but I have never seen a version of that for residential wiring.

However, your design is easily done with home automation controls, such as X10 which can be found at (large) Radio Shack stores and other electronic component retailers—I sometimes see them at Frys. There are other home automation system/components which may be more suitable in your region.

If A and B are wired on the same circuit, a pair of simple on/off switches can control them both, as well as another simple switch to control C. A fourth switch performing a "scene select" function would be needed to generate the A/B and C commands from switch 4. This requires a scene controller.

  • You can do this by connecting two sets of travelers in parallel along with using a four-way switch. See my answer. – ThreePhaseEel Oct 18 '14 at 2:13
  • @ThreePhaseEel: That is impressively persistent! I expect that violates NEC somewhere somehow, if not a particular requirement, then at least in spirit. Woe to any electrician or homeowner who has to come along later and figure out what is going on. – wallyk Oct 18 '14 at 3:45
  • Also, DPDT house-wiring switches do exist...you just don't find 'em at the big box stores, although your friendly local electrical supply house can order them in, or you can find them online – ThreePhaseEel Apr 11 '15 at 4:51
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You may be able to do this using switches like this Insteon device. You would need a white (neutral) wire at each switch and do something like this:

Switch 1 directly controls lights A & B Switch 2 has nothing connected to its load terminal; it is used a remote control. Switch 3 directly controls light C Switch 4 has nothing connected to its load terminal.

You would then set up a scene for lights A&B controlled by switches 1, 2, 4 and another scene for C controlled by 3 & 4.

This can be set up without a separate controller, although if you go to more complex setups you may want to add one.

There are other technologies that may work for this as well; check out "UPB lighting control" and "Zigbee lighting control" with your favorite search engine.

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