light switch to dimmer switch HELP

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  #1  
Old 02-24-07, 04:34 PM
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Question light switch to dimmer switch HELP

I have recently bought a pre-war apartment. I would like to replace an existing light switch with a new (Leviton) dimmer switch. On my existing switch there is a maroon wire and a black wire. On the new dimmer switch, there is a black wire, green wire and two red wires. I understand that one red wire is for a 3-way switch (which I am not using). I am tempted to put black to black, red to maroon and green around the casing screw for a ground wire? I'd like to not cause a fire... what goes where??? Any help you can give me would be GREAT!!

Thanks so much!!!
 
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Old 02-24-07, 05:46 PM
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Welcome to the forums! All you are doing with the switch is breaking the connection, so technically you have a black and a black in the switch box, no matter what the color is. Hook one of the wires on the switch to one in the box, and do the same with the other. Don't strip back the red wire, as it is for the 3 way you mentioned. The grounding wire should be attached to the back of the metal box with a green grounding screw.
 
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Old 02-24-07, 07:36 PM
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The two red wires are travelers, so just use one of them. It makes no difference if you go black to black and maroon to red, or if you swap them.
 
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Old 02-24-07, 08:12 PM
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Ummmm...

Originally Posted by racraft View Post
The two red wires are travelers, so just use one of them. It makes no difference if you go black to black and maroon to red, or if you swap them.
I thank you so much for your input... but... what do "travelers" mean... and what if I dont have a green screw in the back of my box like the previous gentleman suggested? There are new boxes I could buy with this feature, right? I hope?????
 

Last edited by TheDustyDen; 02-24-07 at 08:16 PM. Reason: forgot about something......
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Old 02-24-07, 10:11 PM
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Hello Dusty

You would have made life easier for yourself if you had just purchased a single pole dimmer instead of the 3 way.
Travelers are used with 3-ways where two 3- way switches are involved to control lights. Each one is a hot wire depending on the position of the switch and changes the configuration for switched power.

It will serve no purpose to attach the green wire of the dimmer to the screw of the box (casing screw you call it) unless the wiring has a grounding means all the way back to the main panel. If this is pre war then it is very likely no grounding means exists, unless you have metal conduit which is serving this purpose.... do you have metal conduit or metal cable or any bare/insulated ground wires in the box?

Code requires any switch or dimmer with a grounding means (green wire or yoke screw) to be effectively grounded to an equipment grounding means. If no equipment grounding means exists then a dimmer with a grounding means (green wire) cannot be installed. I do not think you will find a dimmer that does not have a grounding means as an integral part of the dimmer. The ground has nothing to do with the dimmer operation but is there for electrical fault safety.

You need to find out if there is an effective ground fault path back to the main panel before you install this dimmer.


Roger
 
  #6  
Old 02-25-07, 06:17 AM
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Install a ground screw in the threaded hole in the back of the electrical box. Connect the green ground wire there. For an existing setup a new switch does NOT need to be grounded.

Buy and read a good book on electrical wiring. You should not be attempting this project, even though it is simple, without at least knowing the basics. Terms like travelers for three way switches are the basics.

Electricity can and does kill people and start fires.
 
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Old 02-25-07, 06:31 PM
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Bob

NEC 404.9 Exeception to (B) ..... snap switches or dimmers that do not have a grounding means may be installed as replacements as existing. Switches or dimmers that do have a grounding means cannot be installed on existing wiring that does not have an effective ground fault path. If a switch or dimmer without a grounding means is installed as a replacement under this exception you must install a non-conductive faceplate or provide gfci protection.

Roger
 
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Old 02-25-07, 08:34 PM
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All new switches have a grounding means. Are you suggesting that you cannot install them as replacements for older non-grounded switches on older two wire circuits?
 
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Old 02-26-07, 06:25 PM
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No not at all what I'm saying is (rather poorly I see) that if you do install the switch or dimmer in a box where the wiring method does not include a grounding means then the switch box must be covered by a non-conductive trim plate or that part of the circuit must be gfci protected. A CONNECTION to equipment ground is not required for replacement purposes if no equipment ground exists. If your wanting to have equipment ground then you cannot install that dimmer and expect to have effective ground. I know you know this but not the op. My use of the green screw on the yoke was simply (and i see confusing as heck) to point out the connection point.
I see now that I totally misunderstood what you meant by connecting the ground wire to the box with a green screw. You were simply saying that would be the best way to handle the ground wire even if no equipment ground exists.
My poor reading of your advice...my apologies.

Roger
 
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Old 02-26-07, 07:48 PM
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Okay, so we are saying the same thing then. I rarely mention plastic (non-conductive) switch plates because you rarely see them in residential settings.

I always suggest connecting the ground to the metal box jsut in case the metal box is somehow grounded.
 
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Old 02-26-07, 08:06 PM
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Originally Posted by racraft View Post
Okay, so we are saying the same thing then. I rarely mention plastic (non-conductive) switch plates because you rarely see them in residential settings.

I always suggest connecting the ground to the metal box jsut in case the metal box is somehow grounded.

1) you must use a plastic or nylon screws aswell. Or you defeat the purpose (my reading)

2) This is always a VERY good idea. How many old systems do we see with the grnd back wired(nm) or the old BX to a clamp, May not be right... but MUCH better than nothing at all..
 
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