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I'm replacing a light fixture in an old apartment where the ceiling wiring has two brown/red wires and one black wire. When I removed the old fixture it was wired with black to black, the white wire was extended with another white wire with a wire nut and then connected to the two brown/red wires. The old fixture did not have a grounding wire. One of the brown/red wires seemed to be coming down directly from a small hole in the ceiling and the other brown/red wire was coming out from the side of the ceiling along with the black wire.

So, I took my new fixture and connected the black to black, the white to the brown/red that was next to the black and seemed to coming out of the side of the ceiling/junction box (terminology?) and then I connected my green grounding wire to the other brown/red wire that was coming down directly out of the small hole in the ceiling.

I would like to know did I wire this new fixture correctly? It seems to be working just fine and I even tested it with a voltage meter after I turned the power back on in case I didn't ground it correctly.

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What makes you think that the wire you connected to was a ground? Did you perform any tests? It's very difficult to distinguish a ground from a neutral, and you shouldn't mix the two until you get to the main breaker panel. –  BMitch Sep 4 '13 at 12:12
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2 Answers 2

The wires in my house are exactly the same. Everything is run with old cotton braided wires inside a metal BX shielding. The reddish-brownish wire is neutral; the black wire is hot.

So no, you did not hook this up correctly. You should keep it hooked up the way it was before, with the white lamp-wire spliced to the two red/brown wall-wires, and the black lamp-wire spliced to the black wall-wire.


The grounding was provided by the metal BX jacket (which is electrically-connected to the lamp via the metal box). This is not allowed by the NEC anymore, and for good reason: BX cable has high impedance, meaning it does not provide a good electrical connection to ground.

Running a ground wire through the BX cable is extremely difficult (I've tried it). Thus, I'd recommend you install a GFCI at the start of the circuit and connect everything else (including the lamp) to the 'load' side. This is required for 3-prong outlets, and though I don't have the NEC to verify, I would assume the same is true for other fixtures.

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If I connect the new fixture exactly as the old fixture was connected what do I do with the green wire on the new fixture? –  C.R Sep 5 '13 at 0:18
    
@C.R The green wire is ground, so the light will work fine if you leave it connected to nothing. Since the BX jacket (the flexible metal tubing that protects the wires in the wall) is grounded and electrically connected to the metal electrical box the light sits in, I've been tying the green wire to the box, but as I mentioned this is not strictly to code. To be to code, you will either need to run a separate ground wire to the fixture somehow, or attach a GFCI to the beginning of the circuit. –  BlueRaja - Danny Pflughoeft Sep 5 '13 at 9:36
    
@BlueRaja-DannyPflughoeft The GFCI device can be anywhere in the circuit, as long as it protects the new fixture. However, you're correct that installing a combination GFCI breaker is probably the easiest option, as it provides protection to the entire circuit. –  Tester101 Sep 5 '13 at 11:59
    
I'd note that for a ceiling lamp, ground is less of an issue, as it will be rare for anyone (but you) to be touching it while showering/bathing/etc. Replacing the fixture in general does not trigger new code requirements. –  Bryce Jan 23 at 4:51
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It sounds wrong to me, but I couldn't be sure without actually being there. You should connect the new fixture, in exactly the same way the original fixture was connected.

If there wasn't a grounding conductor in the original circuit, replacing the fixture did not make one magically appear. If a grounding conductor is required, you'll have to install one in accordance with local codes.

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If I connect the new fixture exactly as the old fixture was connected what do I do with the green wire on the new fixture. –  C.R Sep 5 '13 at 0:17
    
@C.R Leave it disconnected. If you follow NEC you'll have to either install a proper grounding conductor, or protect the outlet with a GFCI device. –  Tester101 Sep 5 '13 at 11:56
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