Hey everyone --

I'm changing out a ceiling fixture and discovered 7 wires coming into the junction box.

3 are white and wire-nutted together.
2 are black and wire-nutted together.
1 is red.
1 is black.
(I stupidly did not note how the original fixture was wired.)

3 and 4 of these come into the box from opposite sides of the box.

The fixture has only one switch and it is a dimmer.

2 questions: I managed to connect the fixture and it works and it dims. Could I have connected it so that it functions but still could be a fire hazard?

Also, what the heck are all of those wires for?

Thanks

If everything works it is unlikely that you have created a hazard.

Tell us how many cables you have in the box. It sounds like you have two 2-conductor (3-wire) and one 3-conductor (4-wire) cables.

You said 2 black wires nutted together.
1 red
1 black

Does that mean a total of 3 black?

What are the 1 red and 1 black connected to?

Look in switch box and tell us how many wires are there.

Yeah, everything works.

I might not have been clear, though:
There are 7 total wires, including:
3 are white and wire-nutted together,
2 are black and wire-nutted together,
*and* a red one,
*and* a black one. (These last two may or may not have been nutted together, or to anything else, before I removed the old lamp.)

The switch box has three wires in it.

OK, I've added a schematic of the connection box (as best I could).

Notice there are 5 wires coming from one side of the box and 2 wires on the other side.

This is the only config I could get to both power the light *and* have the dimmer work. (One other config gave me power, but no dimming.)

Any ideas what's what?

http://img225.imageshack.us/img225/2690/img056tt6.th.jpg (http://img225.imageshack.us/my.php?image=img056tt6.jpg)

Sorry but can't read you pic, too small. So you have three wires in the switch box. I am assuming that you are not counting the ground. If that is correct what is the third wire connected too and what color is it?
It's beginning to sound like you have a 3-conductor (4-wires) cable going to the switch with an unused conductor.
So how many cables in the ceiling box? A cable is two or more wires inside an outer sheathing. Sounds like you have two 2-conductor cables and one 3-conductor cable. If the 3-conductor cable goes to the switch and one conductor (wire) is unused it all makes sense. The 3-conductor cable goes to the switch box if one of the wires in the switch box is red.

If you click on the pic, it opens larger.

I'm not counting the ground.

Let me take the switch out to see the wiring again.

Thanks for the tip on the pic. Didn't know you could do that.

It appears that you have power coming in on the black wire of one 2-conductor cable which is connected to the black of the second 2-conductor cable going on to another light or receptacle and connected to the black of the 3-conductor cable which goes to the switch. The neutrals of all three cables are connected as well as to the neutral of the light fixture. The power goes to the switch on the black of the 3-conductor cable and comes back on the red which is connected to the light fixture.

The person who installed the 3-conductor to the switch may have done so because he didn't know that the white of a 2-conductor cable could have been used as the return leg.

The installer may have used the 3-conductor cable so that a second wall switch could be used to control the fan of a fan/light combination should one be installed (I would have done such a thing);

He may have taken the neutral to the switch so that an outlet could be installed in that area and just never got around to it (I would have done such a thing);

He may have used 3-conductor cable so that a lighted switch is, or could be used.

Assuming that you find the white wire capped off in the switch box or connected to a lighted wall switch, everything looks fine.