Why are there two sets of wires going to one fixture?

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Old 05-31-05, 10:03 AM
NewbiesNeedHelp
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Why are there two sets of wires going to one fixture?

OK - I just learned a big lesson. Don't dive into somthing for you first time without learning about it first.

I am replacing an old light fixture. It was a light bar with two set of wires (black, white, and ground) going to it. I am replaing it with a smaller fixter that only needs one set. I capped one set of wired and then wired the other set to the new fixture. I turned the pwer back on and the light worked, but the switch would turn it off. So, I tried the other set of wires. They didn't work at all.

??????

That is one problem, and now there is another. My bonehead friend decided to wire both sets into the fixture. That blew the entire circuit. Now, I can't get power going to the circuit at all.

So, anybody have an advice that can help?
 
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Old 05-31-05, 10:54 AM
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Originally Posted by NewbiesNeedHelp
OK -It was a light bar with two set of wires (black, white, and ground) going to it. I am replaing it with a smaller fixter that only needs one set. I capped one set of wired and then wired the other set to the new fixture.
OOPS! First of all, it's not about the fixture, it's about the CIRCUIT! Those wires are there for a reason, and now you've disrupted the circuit - big NO NO unless you are absolutely sure know what you are doing.

was that light on a 3-way circuit; ie, are there 2 switches that operate it? (like opposite ends of a hall)

quite honestly, you guys are an accident looking for a place to happen. you should seriously consider calling an electrician - and sending your friend on a LONG errand.
 
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Old 05-31-05, 03:24 PM
NewbiesNeedHelp
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one switch

It is in a bathroom and only has one switch. That is what is so confusing.

That other thing is that the whole cicuit doesn't work now. The breaker tripped and I reset it, but it still doesn't work.
 
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Old 05-31-05, 03:26 PM
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Newbies, you symptoms are classic. We've seem them before a million times. There is no doubt about what your problem is.

The solution from the beginning was to connect the new fixture exactly like the old one was connected. This approach cannot fail. Tearing everything apart and then trying to figure out how to put it all back together is a really difficult way to go.

You have a switch loop.

Okay, here's what to do. You have two black/white pairs. One is the power feed and one is the switch loop. If you remember your past experiments, you already know which is which. Otherwise you can repeat the first two experiments you did to find out. Do not repeat the experiment tried by your bonehead friend!

The power feed is the black/white pair that makes the light on all the time. The switch loop is the black/white pair that makes the light not work at all. So, now
  • Connect the black wire of the power feed to the white wire of the switch loop. Neither of these wires connect to the fixture.
  • Connect the black from your fixture to the black from the switch loop.
  • Connect the white from your fixture to the white from the power feed.
  • Connect all grounding wires.
That's it. It'll work. I guarantee it.

When you go to turn the breaker back on, be sure to push it all the way to off, and then to on. You may also have a GFCI that needs to be reset.
 
 

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