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Q & A: wiring with grounds

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Most recent answer: 11/01/2014
Q:
I recently moved into an apartment with a high ceiling. Now I have a nice 5-bulb chandelier. It has a negative wire, a positive wire, and a ground wire. I'd like to fix a dimmer switch to the wall (not purchased yet) and then the plug to an outlet, below the dimmer. So chandelier wiring, to dimmer, to standard plug 120V. Is this possible with using/without using the ground wire?
- Project guy (age 28)
NJ
A:

It's possible, but why would you skip the ground wire? The ground wire provides protection by allowing the outside parts of devices with 3-prong plugs to be grounded. That means that if some wire comes loose or water gets inside or something breaks then the voltage from the "hot" wire is unlikely to reach your hand. Instead, current will flow from the hot wire to the ground, probably flipping a circuit breaker or blowing a fuse but not killing anybody. The chandelier has a ground wire for the same safety reasons. Building codes generally require grounded wiring in new buildings, and are particularly insistent on it for kitchens and bathrooms, where the danger of electrocution is highest. (The other wires are usually called "hot" and "neutral" rather than "positive" and "negative", since the voltage is ac. The neutral wire should have a voltage close to ground.) 

If the problem is that there's no ground available in your house wiring in that room, there is a possible solution that's legal in some places. You can use a ground-fault interrupter. These are quite cheap and available in hardware stores.  They sense if the current flowing through the neutral gets out of balance with the current flowing through the hot.  If it is, then current is flowing back through some other path (maybe you) to ground, so the GFI shuts the current down.

Since you don't have a lot of wiring experience, I strongly recommend that you find a friend or neighbor with more experience to help out on this, in case hiring a licensed electrician is too expensive.

Mike W.


(published on 11/01/2014)

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