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My dining room light is currently controlled by 2 different light switches. However it isn't wired how I am used to seeing them. In my old house, there were 2 switches that controlled the dining room light. No matter what, if I toggled either of the switches the state of the light would switch on or off. In my new house, one of the switches will turn the light on off, but only if the other switch is in a specific state. Does that make sense? It's almost as if 1 switch is a switch to allow usage of the other.

Anyways, today I went out to get dimmers for these switches and I wired them up exactly as the instructions said. When I turned the power back on, I didn't get anything from the dimmers however one of the new switches turned the light on in a constant flickering and I heard some noise coming from the switch. I quickly shut the power back off and wrote this question. Any ideas? My house was built in 2013.

UPDATE: I just noticed the bulbs that were installed in my dining room light say "Do not use with dimmers, timers or other control devices" which may be part of my problem. I am starting to think, however that I should only be using 1 dimmer and not 2, in addition to using different bulbs.

UPDATE 2: I may be dealing with a 2-way switch?

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1 Answer 1

Single switches that control a light are called single pole.

When there are two switches that both can turn a light on or off, they are called three way. (I am not sure about the origin of this label, perhaps because it required three wires; it does not mean that there are three or more switches - those are called four way!) In those switches, flipping the on off control on either switch will change its state: if it was off, it will go on, and vice versa.

When a dimmer control is part of a three way setup, one switch usually controls both the level and on/off, while the other switch only controls on and off. Both switches need to be the three way type.

It sounds like someone has put a single pole switch in a system that needs two three ways. Part of the problem is that there needs to be the right wiring between the switches. There has to be two hot wires*. There also may need to be a neutral wire, depending on the wiring configuration.

To determine the solution, we need to know what the wires are in each box that holds the switches, and what wires are currently attached to the switches.

SUPPLEMENT

It is possible to place dimmers at multiple locations if you use certain digitally controlled dimmers. You still need wiring between the dimmers that are able to have two hot lines, called followers, as well as a ground wire. You also need to provide a neutral wire to the fixture. That sometimes is part of the cable that goes through the dimmer boxes, but not necessarily.

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Not sure if you can derive the wiring from this, but here is what the original situation was. Switch 1 would turn the light on and off but only if Switch 2 was in it's ON state. I believe I have a few switches that behave like this, such as the hallway switches when going up a level in my house. –  Brian Sep 2 '13 at 2:22
    
It is almost certain that switch 2 is a single pole switch (only two wires connect to this type of switch). You cannot make this a three way setup unless the right wiring is already in place or you run new wires. Still need more info for a full diagnosis. –  bib Sep 2 '13 at 2:43
    
Switch 1 and Switch 2 are the exact same hardware and both have 4 wires connected to each. –  Brian Sep 2 '13 at 3:17
    
Could this be what I have going on? diy.stackexchange.com/questions/8240/… –  Brian Sep 2 '13 at 3:22
    
What color are the wires? Is one of them green or bare? Are both switches dimmers? –  bib Sep 2 '13 at 15:47

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