tripping the breaker

[kld]

I'm sure this is a basic question for you, but we're having a terrible time. We have a very old house (1912), and are putting in new lighting and switches in the bathroom. The new vanity lights are in and worked with the old dimmer switch, now we want to change out the old switches for new, more attractive ones. The old system was a GFCI receptacle, a dimmer switch for the vanity lights, and an on-off switch for the ceiling lights, each of which is on its own breaker. We changed all 3 but kept the function of each the same (GFCI, dimmer, on-off). Now the ceiling lights and the GFCI receptacle work, but the dimmer keeps tripping the breaker. The GFCI had a green screw to which we attached the grounding wire from the wall, and the regular switch just had the 2 black wires. The dimmer was wired with 2 cables, and had a green wire which we attached with the 2 ground wires from the wall to a screw in the back of the 3-gang metal box, and the 2 white wires are spliced together with a wire connector (this was how it was wired to the old dimmer). We think we wired it correctly , and like it was previously, but now it's just not working. Please help!

[John Nelson]

the dimmer had a green wire which we attached with the 2 white wires to a screw in the back of the 3-gang metal box (this was how it was wired to the old dimmer)
That can't be right. This sounds like somebody was a wire short to do what they wanted, and converted a grounding wire to a neutral wire. Quite a hazard!

Can you give us a total inventory of the cables and wires in the box? Is is just two black, two white, and two green? That's actually not enough wires to do the functions you mentioned. As I said, I think you have a hazard here. You need more wire in the wall to make it safe.

Also, you didn't mention to what you connected the two non-green wires from the dimmer, nor how you connected the GFCI other than its grounding screw. Can you fill in the missing information?

[kld]

Sorry John, I was frustrated with the project last night and gave wrong information. I have edited my original posting. Also, on the GFCI, there was a white wire to silver screw and a black wire to brass screw, which works.

[John Nelson]

Sorry, but we are still far short of the information we need to figure this out..
each of which is on its own breaker
Really? It's of course possible, but unusual for there to be three independent circuits serving the same bathroom.
The GFCI had a green screw to which we attached the grounding wire from the wall
The above makes it sound like there is only one grounding wire in the box, but...
The dimmer was wired with 2 cables, and had a green wire which we attached with the 2 ground wires from the wall to a screw in the back of the 3-gang metal box
says there are more than one. Exactly how many are there?
The dimmer was wired with 2 cables
Does this mean two cables, each with one black, one white, and one bare wire?

Post back (in a new post--do not edit an old one) answers to the following questions. Be precise and complete. Exactly how many cables come into the box altogether? For each cable, exactly what wires are in it? For each wire, exactly where does it go? Do this one cable at a time so I know which black, white and grounding wires go together.

[kld]

Yes there are really 3 separate breakers each controlling only one of the switches.
The wiring is as follows:
On-off switch: 2 separate black insulated cables, each containing a single wire. Each wire is attached to one of the 2 screws on the switch. No ground wire on this one. It works.
Dimmer: 2 separate white insulated cables, each containing a black, white and bare wire. The 2 whites are connected to each other using a wire connector; there are 2 blacks each of which is spliced to one of the 2 black wires on the switch using a wire connector (ie black cable to black wire and 2nd black cable to 2nd black wire); the 2 ground wires from the wall cables are, with the green ground wire from the switch, attached to a screw on the back of the box. This is the switch which does not allow us to flip the breaker on.
GFCI: 1 white insulated cable with a ground, black and white wire. Ground is to green screw on GFCI; black to brass screw; white to silver screw. This also works.

[John Nelson]

Thanks. This is now clear.

The connections sound correct. So we'll have to diagnose where the problem is. Try this: Remove the dimmer, disconnecting it from all the wires that connect to it. Separate all the wires so that they don't touch each other or anything else. Can you turn the breaker back on now? If yes, shut the breaker back off, and connect the two black wires that were connected to the dimmer to each other. Now can you turn the breaker back on?

[kld]

I removed the dimmer and separated the 6 wires. I still can't turn on the breaker.

[John Nelson]

Well, that's a fine kettle of fish. I think we should start looking for the problem at the lights. Tell us what you did there.

And exactly how sure are you that you remember how the switch box was wired before?

[kld]

The light was very straightforward - one white cable containing a white, a black and a bare wire. They were wired to the light white-white, black-black, and both grounding wires together under the green screw. We changed the light before the switches and it worked on the original switch (which did not have a grounding wire). However, I tried to put the old switch back on just to check and I can't turn the breaker on with that one now either. I'm pretty sure I wired it the same way although no pictures were taken! :) Plus, the other 2 switches/receptacles work so they must be right, right?

[kld]

Also, just out of curiousity, I wouldn't mind if both the vanity lights and ceiling lights worked on one switch. Can this be done? I tried tying them both in to the ceiling switch and that didn't work.