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Our foyer chandelier has three outlets that control it. I want to control it with a Belkin WeMo light switch, which specifically states is not compatible with 3-way switches/fixtures, sadly. Well, if I can't convert one of the three switches to be a Belkin WeMo light switch and keep the other two switches working, I'd like to just convert one of the switches to be a WeMo light switch as a single pole, such that the other two switches would simply be left in their on positions.

In my case, the light switch I want to convert/replace has four wires. Two black wires. Two white wires. There appears to be a couple loops of bare copper wire inside the metal box, but currently it does not appear to be connected to the existing switch in any way.

The new Belkin WeMo light switch has four wires of its own. Two black (labeled switch, one with a lightbulb icon, the other with a lightning bolt icon), one white (labeled neutral, with a zero icon), and one green (labeled ground, with the standard icon for ground).

Belkin WeMo Back Wiring

So how might I go about figuring out what wires on the WeMo light switch to connect to what wires currently connected to the existing 3-way switch to pull off this functionality?

Any tricks/hacks that might help me keep the functionality of at least one of the two other three-way switches and have the third WeMo light switch altogether? I do wish Belkin would just come out with a 3-way version already, but until that happens, I guess I'm stuck taking this route if I want the WeMo capabilities (and I do).

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It sounds like the switch you are looking at is the 4way that sits in the middle of the chain. If it is wired with romex there should be 2 red wires as well. Typically, you have source (lightning bolt), 3 way switch, 4 way switch, 3 way switch and then light in a chain. It is also possible to wire it with source and light and then switches but that middle 4 way switch will always have 6 wires with insulation on it. Two of the wires will just be wire capped together, 4 connected to switch. Check to see what is happening in the other two switches. –  diceless Apr 24 at 4:28

3 Answers 3

SHORT ANSWER

You can't convert the WeMo switch to replace a three way. You can add it to a three way circuit to turn lights on and off if and only if the three ways were first set to leave the light on. When you turn off the WeMo (at home or remotely), the lights will go off. When you turn on the WeMo (at home or remotely) the lights will go on. But, if the lights are already off because the three ways were used to turn them off, the WeMo will not turn them on.

LONG STORY

The WeMo light switch is a simple on and off switch (as far as your electrical system is concerned; yes, I know it does more). It allows a circuit to be on or off, based on whether that switch is on or off, period.

A three way switch also turns a circuit on or off. The difference is a three way switch is one of a pair. Each switch changes the state that the other switch has created. For the switch closest to the power supply (A), current comes into the switch on one side (on the common terminal) and leaves the switch on one of the two terminals on the other side (the travelers), depending on which direction the switch is thrown.

On the second three way switch (B), closer to the light or other device, the power comes in on one of the two travelers and leaves the switch via the common if and only if the switch is thrown to the same traveler as switch A.

For three way switches, there is no on or off position. Rather there is traveler 1 and traveler 2 positions (not labeled that way but called that for illustration). The circuit is on when both switches are turned to the same traveler and off when they are turned to different travelers.

current wiring

This illustration also shows the 4-way switch described by OP. 
It also does NOT show neutral and ground wires which MUST be connected as well.

All of the illustrations show just one ON position for the 3-way/4-way setup.
There are actually four possible ON combinations and four OFF combination.

The WeMo can be added to this circuit by placing it between the hot line and the common terminal on three way switch A or between the common terminal and the fixture on switch B.

wemo1

or

wemo2

 These illustrations do NOT show neutral and ground wires which MUST be connected as well.

WeMo effectively interrupts or connects the power either before or after it goes through the three way setup. However, If it three way pair is off (the swithces are not turned to the same traveler), then the circuit will stay of, regardless of the WeMo setting.

Whether this works for you depends on whether you are willing to be sure to turn the three way setup to on before you leave and then control the system with the WeMo.

THE SETUP

The existing switch you are describing does not sound like a three way, but a four way. This is a switch used between two three ways to give an additional location to switch a circuit on and off. (The white wires are actually being used as hot lines and should have been marked with black tape or a black marker). This switch cannot be controlled by the WeMo. You need to find the one of the real three ways to make this work.

When you do, connect the wires as follows:

  1. WeMo GREEN wire to the BARE wires in the box.
  2. WeMo WHITE to WHITE wires in the box.

If you are placing the WeMo next to three way A (closer to line voltage):

  1. WeMo BLACK (Lightning bolt) to BLACK or RED power line currently attached to COMMON terminal on existing three way switch.
  2. WeMo BLACK (Light bulb) to COMMON terminal of existing three way switch.

If you are placing the WeMo next to three way B (closer to fixture):

  1. WeMo BLACK (Lightning bolt) to COMMON terminal of existing three way switch.
  2. WeMo BLACK (Light bulb) to BLACK or RED power line currently attached to COMMON terminal on existing three way switch.

REMEMBER, the three way setup has to be set so that the circuit is ON for the WeMo to be able to control it remotely. (The four way you have been looking at complicates the circuitry, but you can effectively ignore it; just make sure the overall circuit is ON before you leave; it doesn't matter which switch you flip to turn it on.)

SUPPLEMENT

Based on the OP's comment, he or she is willing to lose the 3/4-way functionality and install the WeMo only to control the fixture. That cannot be done by replacing the 4-way switch described because there is no neutral in that box.

The WeMo could be swapped for one of the three ways if there is a neutral in the three way box.

If you are replacing 3-way A, attach the black lightning wire to the black (or red) hot from the line. Attach the black lamp wire from the switch to the black traveler. Cap the white traveler. In the 4-way box, remove the switch and join the two black traveler wires. Cap the whites separately. Place a blank cover plate over the box. In switch box B (closest to fixture) remove the switch. Attach the black traveler wire to the fixture wire. Cap the white traveler wire.

If you are replacing 3-way B, follow the same steps, except in box A, the black traveler is attached to the hot line, and in Box B the black lightning wire is attached to the black traveler and the black lamp wire is attached to the fixture wire.

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Removing the switches and splicing power straight through would be another option. –  Tester101 Jan 10 at 15:43
    
@Tester101 Absolutely. I got the impression OP was trying to preserve the 3/4-way options for use when on site. –  bib Jan 10 at 16:28
    
Yes, I'm aware I would lose the 3/4-way functionality by doing this, I was just thinking wishfully. Since there is no trick/hack, then no, I don't intend to use the other switches once I do convert one of them to the WeMo. With Tester101's suggested approach would I be able to put the WeMo switch at the location I mentioned, which you said was currently a 4-way? If so, how might I wire it up after removing the 4-way switch? –  purefusion Jan 11 at 0:30

There is one way to turn it wemo into a 3/4 way switch.

For this example I will use a 3way switch( which is my setup)

I have one switch set as a "master" )

At this point you have installed the 1st wemo light switch just as per the instructions.

For the 2ed light switch(or 3rd) These are "slaves"

So the ground wire (green) to the bare copper wire The white wire is connected to the neutral wire (should be white, but it may require switching around some of the wires in each box, more on that later) The 1st black wire, goes to the feed (the black wire supplying the power) And the second back wire is unused. Cap it off.

You may have to make changes to where each wire goes in each electrical box. I had to.

At this point you need to setup an account with ifttt ( if this then that )

And for a 3 way switch create 2 recipes.

1: when your 2ed "slave" switch is turned on (the if) Then toggle the master switch (the that)

2: when your 2ed "slave" switch is turned on (the if) Then turn the 2ed "slave" switch off (the that)

For a 4 way switch

You would need 4 recipes (two per switch)

The only draw back at this point is that there is a delay when using ifttt, about 30 seconds or so.

I'm trying to find someway not to use ifttt, there seem be to some people working on some projects that might be able to use a local server instead.

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Well technically you could just add another switch (being the WeMo) with a new hot leg tied directly to the chandelier. And keep you 3/4 way setup. With only one drawback. The WeMo will be god and the 3/4 way will function as normal when the WeMo is off (A good setup if you intend to use WeMo mostly for away mode or alarm mode). You tie the power and neutral in straight from mains line in. And connect the WeMo out (light-bulb) to the chandelier (or the 3 way b common). The WeMo can turn the lights on and off. When the WeMo is on the lights will always be on. When the WeMo is off the lights will be on manual control. Either on or off depending on the last setting.

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