3 way switch using 2 conductor wire


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Old 11-17-07, 12:13 PM
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3 way switch using 2 conductor wire

My house is from 1961. While doing some electrical work, I found that my stair case is wired as follows: 1st 3way switch->2nd 3way switch->light. However, there are two very strange things. First, there is only a 2 conductor wire connecting the 3 way switches. Second, both 3 way switches are connected to different circuits. It appears to be taking neutral from one circuit and hot from the other. This has been working correctly for ~45 years now. I don't understand how or if it is dangerous. Any help would be appreciated. Thanks! Dan
 
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Old 11-17-07, 12:35 PM
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Are you sure it is on two different circuits? Just because the power is supplied at one switch and the lamp neutral is from a different physical location does not necessarily mean that it is on two different circuits.
 
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Old 11-17-07, 01:03 PM
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Yes, this is illegal and dangerous. You should address it immediately.
 
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Old 11-17-07, 01:33 PM
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Yes. It is definitely connected to 2 different circuits. (not just because its different locations). In fact, if I turn off either circuit, the lights go to 50%.

The problem then is how do I now run 3 conductor wire through existing walls? Can I just wrap the ends of the old 2 and the new 3 conductor together, tape them and pull really hard and hope they don't come apart?

Thanks again.
 
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Old 11-17-07, 03:27 PM
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No. You must find a way to run the wires, making holes in the walls if you have to.
 
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Old 11-18-07, 01:20 PM
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Wireless 3 way switches

As a followup, there are a few wireless 3 way switches available online (Levitron seems to be the most popular) instead of pulling 3 conductor cable through the wall.
 
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Old 11-18-07, 02:16 PM
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I was curious about whether these were RF or powerline signal devices, so looked them up. (Answer is RF)

Looks like a bad solution to me. The ones I saw required AA batteries. When the switch doesn't turn on, a person who wasn't aware of the install is not going to start taking apart switches looking for batteries.

They are only A/B selectable so you can only have two and you're done.

Worst thing: They seem to be only for incandescent bulbs from what I read. Since they have independent battery power I see no reason why this limitation must exist... perhaps it's just due to a dimming feature it may have. It didn't say that it had dimming but who knows. Ahh... on second thought probably only the remote switch has the battery power. The main one trickles power through the filament.

I'd pass on these, especially with CFLs becoming so popular. If you can find ones that require a neutral and thus support CFLs that would be another matter.
 
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Old 11-18-07, 11:14 PM
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What is it called? A california 3-way or carlton 3-way? There's an old way to make a switch work as a three way with two conductors. It is illegal now, as it switched the neutral and hot lines.
 
 

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