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rockycmt
01-05-2009, 11:26 AM
3 way with a dimmer

I want to wire a new 3-way circuit with a dimmer. I have done 3-way circuits before and know there are different approaches depending on where the switches are vs the fixture. Can I simply swap out the standard 3 way switch with a 3 way dimmer is any of the layouts? Are there any restrictions?

Any oppositions to a 3-way dimmer?

220/221
01-05-2009, 04:03 PM
Just make sure you put the common wire in the right place.

Generally it is the odd colored wire on the dimmer.

Put it on either end.

edlentz
01-05-2009, 08:13 PM
I installed a 3 way dimmer this summer and it replaced ONE of the 3 way switches. It works fine. The other 3 way switch turns the lights off, the dimmer dims and turns off the lights as well.

frenchie
01-05-2009, 08:21 PM
You can also have one on each end. Double your cost & time, but well worth the convenience, IMO.

jar546
01-05-2009, 09:17 PM
Just make sure that the dimmer is rated for the total wattage of the bulbs you will be controlling. Leave the heat sink tabs on the dimmer.

rockycmt
01-06-2009, 06:40 AM
Jar,
You bring up a good point I think. Or something I did not know. What consequences would I expect if the dimmer is not rated for the total watts of the fixtures?

220/221
01-06-2009, 09:01 AM
You can also have one on each end. Double your cost & time, but well worth the convenience, IMO.

It will WAY more than double the cost and time.

A standard 3way dimmer is about 15 bucks. An electronic master/slave set up is well over 50 bucks and requires a bit of rewire.

Rarely worth the convienience IMO.

Rocky, Dimmers get hot in normal installations. If the watts exceed the dimmer it will get really hot and burn out quickly.

jadnashua
01-06-2009, 09:23 AM
Depending on how far apart the switches are, it can be a real convenience to be able to dim from either end...it's up to you whether it is worth the price. Some of them are great if you need more than just two, as you can daisy chain up to 8 switches, each can turn on and off plus dim. The wiring is easier, too, but different. The hot and neutral are chained, and the third wire is the dimmer interconnect. Imagine trying to get 8 switches all working to control the lights without that technology...messy. A good electronic dimmer also saves bulbs since they perform a soft start which doesn't shock the filaments as much.

jar546
01-06-2009, 11:38 AM
It will overheat and burn out quicker and not work properly. It would be a fire hazard.

jadnashua
01-06-2009, 04:21 PM
My guess is that a metal electrical box with a dimmer might also help act as a heat sink and help the life of a dimmer verses a plastic box.

jar546
01-06-2009, 06:34 PM
My guess is that a metal electrical box with a dimmer might also help act as a heat sink and help the life of a dimmer verses a plastic box.

As long as I know ahead of time, I use metal boxes where dimmers will be going.

frenchie
01-07-2009, 04:43 PM
It will WAY more than double the cost and time.

A standard 3way dimmer is about 15 bucks. An electronic master/slave set up is well over 50 bucks and requires a bit of rewire.

Rarely worth the convienience IMO.


Point taken on the materials, but why would it call for any rewiring?

Chris75
01-07-2009, 04:58 PM
My guess is that a metal electrical box with a dimmer might also help act as a heat sink and help the life of a dimmer verses a plastic box.

Since the heat is directed to the front, a metal box does nothing. besides, the dimmer is rated what it is. what gain would you get from using a metal box?

220/221
01-07-2009, 05:11 PM
Point taken on the materials, but why would it call for any rewiring?

The master/slave units I have seen needed power at both ends and one traveler between them. It's not complicated rewiring but it is rewiring.....(edit) if it's a retro install. If you've prewired for it, no problem.

codeone
01-07-2009, 07:12 PM
Since the heat is directed to the front, a metal box does nothing. besides, the dimmer is rated what it is. what gain would you get from using a metal box?

Metal to metal contact causes heat disipation, not that it would necessarly help in this paticular application to make a differance.

jadnashua
01-07-2009, 07:17 PM
The metal yoke contacting with the metal box would transfer at least some heat to the metal...in a plastic box, there's not as much conduction. Effectively, I think it would make the heat sink a little bigger. Probably not enough to worry about.

frenchie
01-08-2009, 08:25 AM
The master/slave units I have seen needed power at both ends and one traveler between them. It's not complicated rewiring but it is rewiring.....(edit) if it's a retro install. If you've prewired for it, no problem.

Really? The ones I've seen basically replaced the old 3-ways; I've only had it done 3 times, but my electrician didn't rewire anything.

I just did a little google hunt, found the installation instructions for lutron's multi-location dimmers. Look at the diagram for 3-way dim-from-either-location. Looks like a standard 3-way setup, to me...


...upload's not working, for some reason. I think the file's too big. Here's a link to the download page:

http://www.lutron.com/CMS400/page.aspx?id=16977&mn=1815