Switch box wired strange

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  #1  
Old 01-16-13, 01:55 PM
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Switch box wired strange

The switch box has only 2 wires coming in to it, 1 is green and 1 is white. This box had a single pole dimmer switch installed in it controlling 4 wall lamps in a vanity. The dimmer has 2 black wires and 1 green(ground) wire. Here is where the strange comes in, the green wire inside the box is "hot" it isn't a ground the white is "neutral" there are no other wires at all in the box. The dimmers ground was never hooked up and 1 black wire went to the green and one black went to the white. I had removed the dimmer which worked fine before and after I reinstalled it it never worked again. I tried a new dimmer and when I turn the breaker back on it fried it. Shouldn't there be 2 "hot" wires coming into the switch box? And if so how was this ever working before?
 
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Old 01-16-13, 02:07 PM
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Welcome to the forums.

Sounds like a switch loop where the green is your incoming hot and the white takes the power back to the fixture. A green wire is not allowed for this.
 
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Old 01-16-13, 02:07 PM
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Shouldn't there be 2 "hot" wires coming into the switch box?
Yes.

Is this conduit because I wouldn't expect a green wire unless maybe conduit. You need to open the lights to get a better idea whats going on but as it stands the switch should be rewired.
 
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Old 01-16-13, 02:26 PM
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I think it is conduit but not positive. This is in a condo if that helps at all. I had all the lights off before (I was painting the walls) and in 1 of the light boxes was a highway of wires. When I took them all off I labeled the wires because some of the black wires on the lights went to red wires in the box. All the lights went up exactly how I took them down. The weird thing is the dimmer worked before I took the lights off. That's why I ended up investigating the dimmer and the wires going to it, it never should have worked in the first place right?
 
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Old 01-16-13, 02:48 PM
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I can see it working but it was not code compliant.
 
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Old 01-16-13, 03:21 PM
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the green wire inside the box is "hot" it isn't a ground the white is "neutral" there are no other wires at all in the box.
No. One of those wires is the "hot" wire, or ungrounded conductor. To determine which one that is, you remove the switch - dimmer or otherwise - separate the wires and test for voltage with a multimeter.

If the box is a grounded metal box, you can test from each wire to the box. If not, you can plug a 2-prong extension cord into a known good outlet and use the neutral (larger straight) and ground (round) slots in the female end of it for one probe from your meter.

The other wire carries the ungrounded power from the switch to the lights. It is also a "hot" wire, but only when the switch is closed. There is no "neutral," or grounded conductor, in this box.

The dimmers ground was never hooked up
Was it connected to the box?

I tried a new dimmer and when I turn the breaker back on it fried it.
Some dimmers want you to distinguish between the power coming in and the power going out. Wiring one of those the other way around might damage it.

For this outlet to be fully code compliant, there should be not less than three wires in it, and possibly four. Two of those wires need to be black or red or any color except white, gray or green. Those will be the power-in and power-out wires. The third wire should be white, and needs to be bonded to neutral in the box it is pulled from. It can be capped off it it's not needed. The fourth wire should be green, and be bonded to ground at the other end. It is only needed if the box is plastic, or ungrounded metal. If needed, it seeds to be connected to the switch and to the box, if it's metal and isn't otherwise grounded.
 
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Old 01-16-13, 03:38 PM
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The green wire inside the box is the "hot" wire. So that must mean the white wire is the ungrounded power. The box is metal and no the ground wire from the dimmer was not connected to the box. The new dimmer had 2 black wires and one ground wire like the old one.
 
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Old 01-16-13, 03:53 PM
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We need to know the wiring at the light.

Do you own the condo?
 
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Old 01-16-13, 04:37 PM
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The green wire inside the box is the "hot" wire. So that must mean the white wire is the ungrounded power.
I don't think you heard what I said. I regret that I wasn'a as clear as I would like to be.

The "hot" wire is the ungrounded power. If you know that is the green wire, connect it to the power-in wire on the dimmer. Connect the white wire to the power-out wire on the dimmer.

The box is metal and no the ground wire from the dimmer was not connected to the box. The new dimmer had 2 black wires and one ground wire like the old one.
Once you've got the lights working again, test to see if the box is grounded and rewire it as described earlier.

If you need to, you can kill the power, connect the green wire to the white wire with a wire nut, and turn the power back on to see if the lights work. You can also put a regular switch on the two wires and try that.
 
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