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-   -   black to black, white to ground? (http://www.diychatroom.com/f18/black-black-white-ground-16832/)

klassa 02-09-2008 08:17 PM

black to black, white to ground?
 
I've got a couple of spotlights that are fed from a single switch.

The lamp holder on one of the two broke, when I tried to redirect the beam. Since the fixture is pretty high off the ground, I asked my painter to replace it (and the other, so they'd match) while he was painting my house.

He replaced both, but they no longer work. Unfortunately, I didn't see how they were wired prior to his replacement attempt.

At the moment, they're hooked up black-to-black, white-to-white, and the ground wire is screwed onto the fixture.

When I started to poke around today, I took a meter to the wires to see what I was dealing with. With the leads connected as follows, I got the indicated voltages:

black-to-white: 0
black-to-ground: 120
white-to-ground: 0

Shouldn't black-to-white give me 120V, too?

Regardless, I suspect that if I connect the fixture as black-to-black, and then take the fixture's white and attach it to the house ground, it'll work. Of course, I also don't know if that's a bad idea. :-)

So, two questions:

1. Are the voltages I'm reading normal? Seems to me like the white wire might just be floating (which would be wrong, wouldn't it)...

2. Will black-to-black, white-to-ground hurt anything? A friend was concerned that I'd be electrifying everything that's grounded. I didn't think that would be the case, but thought I'd ask first. :-)

Thanks.

nacko 02-09-2008 08:24 PM

you do not want to connect the white and the ground. sounds like you need an electrician to figure out what is wrong.

klassa 02-09-2008 09:32 PM

Yup... More poking around (beyond what I did prior to asking) leads me to understand that I have an open neutral (and that white-to-ground would give me a "bootleg ground", which is dangerous). Enough said. Thanks!

idoelectric 02-09-2008 10:30 PM

2. Will black-to-black, white-to-ground hurt anything? A friend was concerned that I'd be electrifying everything that's grounded. I didn't think that would be the case, but thought I'd ask first. :-)
.[/quote

Yes, connecting neutral (white) to ground can, not only be a potential fire hazard but can seriously hurt or kill someone given the right circumstances.

The problem you are having appears to be an open neutral, which is not that hard to locate with a little patience.

The neutral acts as a return back to the main panel thus to the transformer on the light pole to complete the circuit. The neutral wire carries no voltage but carries current from whatever load it may have. The current flowing through the wire will create heat which is why wire is sized for the electrical demands and partially why it's insulated.

The purpose of the ground wire is for safeguarding from lightnig and for protection of persons and property of electrical hazards. The ground is never intended to carry voltage or current, period. Connecting the neutral to ground (bare) can cause the wire to heat up enough to start a fire anywhere inside the walls or in the attic. Also, touching metal electrical devices or fixtures may cause an electrical shock that can really hurt or worse, kill you or your family.

I'm not trying to spook you with this. Just informing you of the consequences of improper wiring methods for your own safety.

klassa 02-10-2008 08:38 AM

Not at all -- thanks for the helpful info! I appreciate it!


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