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Switch Junction box has 3 sets of 3 wires. Can't get dimmer to work

45K views 14 replies 11 participants last post by  Speedy Petey 
#1 · (Edited)
Hey There,
I'm trying to wire in a dimmer switch for my living room but the process isn't going as smoothly as I had hoped.

The light switch I am trying to replace only controls a single light fixture on the ceiling, as such, I purchased a single-pole dimmer switch for this application.

The dimmer switch I have has 2 black wires and one green wire. It's a Diva which is made by Lutron.

The junction box is where I run into the problem. It has 3 sets of wires coming into it. Each set of wires has a black wire, white wire, and a bare copper wire.

The white wires are all connected using a plastic twist cap thing and the bare copper wires are all connected using a plastic twist cap thing as well. This leaves me with 3 black wires to connect to the dimmer switch.

To this point, I've tried all possible combinations, but it never works properly. I always end up with one of the following scenarios:

1) Nothing works properly,
2) The living room works properly with the dimmer switch but the kitchen light stops working, or
3) The living toom light doesn't work at all but the kitchen light works with the dimmer switch.

My house is approximately 8 years old so I can only assume that the wiring was put in properly and the former tennants didn't mess around with the wiring.

Any thoughts on this one? I don't want to sit in the dark for much longer.
:)

Cheers!

PS - I just checked the old switch and it has two of the black wires connected to the bottom (one in the hole and the other on the screw) with the third wire connected to the top.

The old switch doesn't have a green ground screw either.
 
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#2 ·
Are you sure you have a single or a 3 way circuit? Could you control the light in question from more than one location (switch)? If your original switch had three wires not counting the ground it is a 3 way switch.
Thats why you SHOULD have MARKED the wires so you could install them back like before!

Please respond to this question for further instructions.
 
#4 ·
Are you sure you have a single or a 3 way circuit? Could you control the light in question from more than one location (switch)? If your original switch had three wires not counting the ground it is a 3 way switch.
Thats why you SHOULD have MARKED the wires so you could install them back like before!

Please respond to this question for further instructions.
Yep !
 
#5 ·
What it sounds like to me is that the three wires do the following:
1. Power coming in to the box(Incoming Power)
2. Power going out to the kitchen light switch box(Outgoing Power)
3. Switch Leg going up to your living room lights (Switch Leg)

The 2 wires on the bottom (one on the screw and the other in the hole) are both the Incoming Power and the Outgoing Power which need to be connected together with the one of the black wires going to the dimmer(check the instructions on the dimmer, one black wire might be specifically for the power). The switch leg (the last black wire in the box) needs to be connected to the second black wire on the dimmer. The Green wire on the dimmer connected to the bare copper wires from all 3 cables coming in. It would help alot if you posted a picture of the old switch to determine if it is a Single Pole switch or if it is infact a 3-Way switch(one light, switched from 2 locations.)
 
#6 · (Edited)
Simple.

Two of the black wire go together (power in/power out) along with one black from the dimmer. This gives you power in, power out and sends power to the dimmer.

The remaining black connects to the other black from the dimmer. This sends the power to the fixture.


On the original switch, the blacks that were on the bottom are the power in/out.

Hook the dimmer green to the bares.
 
#7 ·
Hey,

Thanks for the response. Yes, the light in question can only be controlled from the one switch. It isn't a three way switch like I have in my upstairs hallway, which I can turn on from upstairs or the main floor.

I've hooked everything back up so it is working properly with the old switch.

As I said, I have one black wire connected to the top screw of the old switch and two black wires (one inserted into the hold and one connected to the screw) connected to the bottom.

Here is a picture of the old switch which is now connected with everything working:


Here is a picture of the junction box with the three sets of wires inside. You'll see two yellow connectors inside. One connects the three white wires and the other connects the three bare copper wires.
 
#9 ·
Problem Solved

Hey,

I just wanted to chime in and let you know that everything is now working properly.

Thanks williamj001 and 220/221.

You both told me the right way to wire my dimmer switch. Now all the lights are working as they should.

Thanks again!!!

Now I just have to clear some wire out of the junction box because it's so tight that the dimmer barely fits inside.

Cheers!
 
#13 ·
Recess lighting dimmer plus fan/light switch

Hi all,

I am currently replacing a fan (with light kit). Since it was not properly wired, i purchased a maestro fan/dimmer control with canopy, so i didnot need to rewire. Anyway, when I tried to replace the controllers on the wall what I found is the following: 3 sets of 3 wires (1black, 1 white and one bare copper per set). One set is marked "in", one is marked "main" and the other does not have a label. I need to install 2 controllers, one maestro dimmer/fan controller and one skylark dimmer. I am really confused on how to wire this. I hope someone can suggest something on this!
 
#14 ·
Same problem but fancy dimmer switch

Hi,

I have this same 3 black wire problem with one black wire connected under a screw at the bottom of the outlet, another one in the hole next to that screw and then the last black wire is up higher in a hole. The 3 white wires are capped off an the ground wires are crimped together.

I am trying to replace a regular single pole outlet with a fancy dimmer switch. The dimmer switch has a connection at the top labeled common with two holes, a green connection at the top for ground with one hole and then a gold screw at the bottom with two holes next to the screw.

I am not sure which black wire goes in the common and which black wires go to the gold. Can someone help please?
 
#15 ·
Hi,

I have this same 3 black wire problem with one black wire connected under a screw at the bottom of the outlet, another one in the hole next to that screw and then the last black wire is up higher in a hole. The 3 white wires are capped off an the ground wires are crimped together.

I am trying to replace a regular single pole outlet with a fancy dimmer switch. The dimmer switch has a connection at the top labeled common with two holes, a green connection at the top for ground with one hole and then a gold screw at the bottom with two holes next to the screw.

I am not sure which black wire goes in the common and which black wires go to the gold. Can someone help please?
Duplicate: http://www.diychatroom.com/f18/3-black-wires-new-dimmer-switch-226025/
 
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