Two dimmers, two circuits, one box, one supply

justinae

I've got two sets of can lights independently controlled by separate dimmers. They are on different circuits. They were installed by a professional electrician. We are just switching out the color of the dimmers so I thought it would just be a straight up replacement. Well the wires got somehow crossed and I lost my reference point. Here's what is in the box:

1 B/W/G that is the supply
2 B/W/G going to the cans

Two of the wires are new looking from when they installed the cans and so I thought the old wire would have been the supply. But it turns out that one of the newer wires is the supply. I tried nutting all the whites together and pig tailing the blacks but that's when they were a separate circuit cause it just tripped the breaker.

I've tried many configurations and currently I have the switches so that one works, but the other only works if the first one is on. Seems like I'm close.

Any help?

thanks!

oh yeah, it's not a 3 way and there is no red wiring. I can easily take a picture and upload if that will help.

joed

Two dimmers and two cables means there is no feed. You have two switch loops. Connect the black and white from one cable to one dimmer and the BW from the other cable to the other dimmer. Connect all the grounds together and to the green wire from the dimmer if there is one.

If there is more than two cable then tell us ALL the cables in the box.

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SD515

I suspect that one of your cables entering the switch box may be a switch leg from the cans. If it is, and was done correctly, power would enter the switch box on the white wire, and when you tied all the whites together, it created a 'dead-short' and tripped the breaker.

Using a voltmeter/tester, you can determine which is which, if that's the case. If you're not comfortable working with live electricity, stop (!) and have a qualified person look at the situation.

If it is as I suspect, the cable from the panel (source cable) is going to have voltage from black to white and black to ground. The cable that goes to one set of cans isn't going to have voltage black to white, black to ground, or white to ground. The third cable, if it is a switch leg, is going to have voltage on either the black or white to ground, but not black to white. Per code, it should be on the white, and the white re-marked (a black sharpie works nice).

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Kyle

Just because you can, doesn't always mean you should

SD515

Joe, I thought the OP meant there are 3 cables in the sw box. Maybe I mis-understood.

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Kyle

Just because you can, doesn't always mean you should

justinae

Yes three romex wires total coming in.

Im fine working live. That's how I found out which was the black supply. Don't have a volt tester so I can test if white is hot.

SD515

I'd suggest getting a inexpensive voltmeter...handy to have around...and test as I described above.

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Kyle

Just because you can, doesn't always mean you should

justinae

Before I do that is it correct that I should have 3 blacks and 1 white and it is some combination of those 4 connecting to the 4 terminals. Dies it matter whether I connect to the bottom or the top terminal if they are both gold colored?

AllanJ

Three Romex cables with 3 blacks and one white, something's missing. THere's got to be more wires.

You can use a light fixture such as a table lamp for a voltage tester in this situation. Cut two 4 foot sections of #14 to #20 gauge single conductor wire, attach one wire to each plug prong, tape it up well so no metal is exposed, and use the two free ends to test for presence or absence of line voltage and find which wire is the feed.

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SD515

???

You said you have 3 cables coming in. That should be 6 wires not including grounds. Are you eliminating the cable you know is a source cable? Leaving 4 wires (2 cables)?

If that’s the case, I’d bet you have one cable that has blk & wht, and the other has 2 blacks, and that cable has had its white re-marked to black. And if that’s true, I’d bet that the cable with 2 blacks gets hooked to one switch, one black to a terminal, the other black to the other terminal. That switch is done.

The other switch gets the black of the source hooked to it, the black of the last cable hooked to it, and whites tied together.

Make sense?

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Kyle

Just because you can, doesn't always mean you should

justinae

The electrician just left. There was an outlet on the circuit that had been switched before and when it was replaced was unswitched. Problem solved!
Thank you for all the fast help.