No ground wire in light switch

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Old 10-08-12, 06:30 PM
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No ground wire in light switch

I'm trying to hook up a dimmer switch (3-way) and have discovered that there is no ground wire connected to the switch. I can see that there is a copper wire back in there, but it's been cut short - too short to attach the green ground wire from the dimmer. Is it okay to just go ahead and install the dimmer minus the ground wire? Apparently, that's the way it's been for several years!!

Thanks!
Micha
 
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Old 10-08-12, 06:42 PM
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If that's the best you can do then that's the best you can do. But first, is the box metal or plastic?
 
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Old 10-08-12, 06:43 PM
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Technically, no. I know it has been that way for years, and back "when", hacks cut the ground wire thinking it served no purpose in lighting. Is this in a metal box? Is the grounding wire attached to the box via a green screw in the back of the box? Does your dimmer require a neutral? Most don't, but read the directions first.
 
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Old 10-08-12, 07:22 PM
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update: I went ahead and installed the dimmer minus the ground wire but when I turned the power back on, there is a humming noise coming from the dimmer switch and the 2nd light switch doesn't work now. What did i do wrong? Here is how I wired it: The dimmer has 4 wires (black, green and 2 red). The switch has red, black and white (Neutral) I connected neutral wire (white) to one red, then matched black to black and red to red - perhaps i should switch the reds?

Metal box - yes there is a neutral wire (white) attached to black screw.
 
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Old 10-08-12, 07:26 PM
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ground wire cut short

I can see the bare ground wire coming out of the cable, but it's been cut short and there is no way i can connect it to anything.
 
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Old 10-08-12, 07:33 PM
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When you pulled out the 3 way switch it should have had an odd colored (usually black) screw on it. The wire that was attached to that screw is the one that goes to the dimmers black wire. The other 2 wires from the switch go to the reds. Maybe you could try connecting the ground wire to the clamp screw at the back of the box if possible.
 
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Old 10-08-12, 07:44 PM
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The switch has red, black and white (Neutral)
No, not a neutral. It is a hot wire that was probably not remarked in a code compliant way such as colored tape or felt tip marker to indicate it is not used as a neutral. Please review the good advice given by Micha.
 
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Old 10-08-12, 07:52 PM
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OK - The white wire was connected to the black screw - i connected it to a red one!! So then i connect that one to the black? (I thought the instructions were confusing!)

Yes, there is a screw on the inside of the box on one side - i could connect the green wire to that.... I'll try it now. (sure is getting dark!)
 
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Old 10-08-12, 07:59 PM
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I misunderstood the instructions and thought it said the black screw was the neutral wire!!

I re-wired like this: black wire from dimmer to white wire (which was attached to black screw); red from dimmer to red and red from dimmer to black. I attached ground wire to screw inside box.

dimmer still hums but 2nd switch works now.

Any idea why the humming?
 
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Old 10-08-12, 08:10 PM
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On a dimmer (or a light switch) there is usually not a neutral wire. On a 3 way switch circuit the white wire could be used in several different ways. The key to working with a 3 way switch is that there is ALWAYS an odd colored screw on it. As long as you match that the other wires don't make a difference.

Some dimmers just hum. Could be the quality. Make sure the dimmer you're using is right for the job. You could replace the dimmer with another new one and it could be quiet.
 
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Old 10-08-12, 08:28 PM
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So then the wire attached to the black screw (in this case the white one) should be connected to the black (hot) wire - correct? Here is a pic of the instructions, which looks to me like the black wire should be attached to a red one, which was confusing to me but looking at it now - I see where i went wrong!

[ATTACH=CONFIG]4154[/ATTACH]

Thank you all for your help - I'm still a little afraid of it because of the humming and the ground wire business!
 
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Last edited by Micha; 10-08-12 at 08:49 PM.
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Old 10-08-12, 08:39 PM
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That pic shows the hot (source) power going to the 3 way switch first. Using one of two of a same color (red) for common is an issue. How can you tell which red is which ? I see the diagram but are the reds labeled somehow?
 
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Old 10-08-12, 08:53 PM
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No - there was no other label. The wires are arranged so that a black and red come out of one end and a red and green come out of the other - but not sure if that has any significance -- see why the confusion? I'm about to take it back and get another one!
 
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Old 10-08-12, 08:56 PM
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Very confusing....definitely doesn't conform to the normal.
 
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Old 10-08-12, 09:04 PM
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I'm taking it back to Ace tomorrow and get a different kind! I installed one in a different part of the house last week with no problem - course it was a single pole, but I've never had this much difficulty with dimmers before!

Appreciate your help ... and your confirmation that it wasn't just me thinking the instructions were confusing!
 
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Old 10-08-12, 09:13 PM
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It is better to use the term odd colored screw or dark colored screw. It isn't really black usually and has no connection to black wire. There are no code standard color codes for this except a factory green wire can't be used for a "hot" wire nor can a white wire unless recolored any color except white, gray , or green. It can be recolored with a band of tape on both ends or a felt tip marker or paint. Which wire goes to the common (odd colored screw) is installers choice.

Just remember line (power in) to one common and load (power out) to the other common.
 
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Old 10-09-12, 12:17 PM
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Update

Hi,

Just thought I'd let you know that the dimmer installation issue is solved! I took the dimmer switch back to Ace this morning and spoke with a very knowledgeable employee who agreed about the confusing instructions and drew a diagram to show me how everything works and then told me how to wire it - which was just as i had done last night - white from box to black on dimmer; black and red from box to 2 reds on dimmer. I exchanged the dimmer switch for a different one - same kind/model, etc., but now everything works perfectly, there is no humming and I'm happy! Apparently the dimmer i purchased originally was just a faulty switch.

Thanks again for your help!
Micha
 
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Old 10-09-12, 12:24 PM
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Glad you got it. Thanks for letting us know.
 
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