Lighting, Light Fixtures, Ceiling and Exhaust Fans - Not sure what kind of wiring I have. . .

I am installing a 3 way dimmer (don't need 3 way, just picked the wrong item) that has two red wires and one black wire, plus the green attached to the dimmer box. I don't want to break any brand name rules on the forum, so will say that this is a very common brand of dimmer, and is model S-603P.

My bathroom light box has two sets of three wires. Each set of wires contains a black, a white and a copper-colored bare wire. On the on/off switch that is in there now, the black wire from each of the two sets is connected to one of two separate holes in the back of the on/off switch. The two white wires are connected to each other, and the two bare copper wires are connected to each other. One smaller copper wire connects from the two joined copper wires to the box (not to the light switch) in the wall.

The old light switch itself has two screws on one side of the switch, and one screw on the other side. None of the screws are used--just the two black wires are connected to the two holes in the back of the switch.

Can you please tell me what kind of circuit I have, single pole or three way, and how to hook up this dimmer? Of course, I know power must be off, so that can be skipped. Thanks!

in your post correctly, the light switch you want to replace has only two black wires connected to it, plus a bare ground wire?

If that's correct, then you have a single pole circuit. The wires in the holes are electrically the same as the side screws. You don't want to change or move any of the other wires in the box, just the ones connected to your old switch. To remove the old wires, look on the back of the switch, where the wires go in. Just below each wire hole, there should be a slot. Insert a small screwdriver into the slot and push in. This should release the wires. If there's enough extra wire, then you could simply cut the wires as close to the switch as possible.

You can use the dimmer you have, I got this info from the support section of the maker's website here: http://www.lutron.com/service/FAQ.asp

"CAN I USE MY 3-WAY DIMMER IN A SINGLE-POLE APPLICATION?
Yes, you will use the black wire on the dimmer, and only one of the red wires. If you have the Diva or Ariadni style dimmer, and the paddle/toggle switch works backwards, just change which red wire you use. If you have the Ariadni with the screw terminals, use the copper colored terminal and one of the brass colored terminals. If the switch works backwards, just change which brass terminal you are using."

So connect the black wire to one of your old black wires (shouldn't matter which one), then one of the red wires to your other black wire. Green to ground/bare wires. Cap off or carefully tape the extra red wire.

I hope this helped!

Thank you so much for the info, Desy2820. It was just what I needed to know, and the light is now hooked up and working fine. I'm especially glad that you suggested cutting the wires as short as possible, because even having done that, it was quite a task to fit the dimmer box into the small space that housed the simpler light switch before.

Thanks again,
JudyLou