Wiring problem

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  #1  
Old 01-23-07, 11:31 AM
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Wiring problem

Hello, I'm trying to replace a ceiling light. I took the old light off. There are four wires coming out of the ceiling. They are all
black. I have no idea which wire is which. Can I put new wiring in? How can I determine which wire is which? Thanks
 
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  #2  
Old 01-23-07, 11:33 AM
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You should have paid attention to the wiring that came off the old light.

Look at the wiring at the switch, look at the cables or conduit that the wires come out of, and use a meter to figure out what you have.
 
  #3  
Old 01-23-07, 11:39 AM
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Wiring problem

Hello, there is no switch, it's a pull chain. What kind of meter
are you talking about. There are four wires coming out. What
different kinds would there be. As you can tell I should never
have attempted this project.
 
  #4  
Old 01-23-07, 11:46 AM
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What do th wires come from? Cables or conduit? Do they come from two cables? Two conduits? What else is on this same circuit?

Two of the wires bring power into the this box and two take power on to the rest of the circuit. You need to match the wires up properly and get one of each to the how wire for the new light and one of each to the neutral for the new light.

It is also imperative that you get the outgoing neutral matched with the incoming neutral and the outgoing hot matched with the incoming hot. What kind of tester do you have. If you don;t have a tester, go and buy one. Purchase a two wire tester with a little light in it.
 
  #5  
Old 01-23-07, 01:30 PM
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Wiring problem

Using a voltage detector I've determined that one set of wires
are hot,or the supply wires,and the other set gets no reaction
from the detector. The wiring for the new light has a white
and a black wire. Problem is the set of hot wires,probably from age?, are both black. How can I tell which is the white and which is the black?
 
  #6  
Old 01-23-07, 01:45 PM
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Are the wires cloth covered? If the box is grounded you can identify the hot by measuring voltage between each wire and the box. The hot will be 120V. The neutral should be 0.

If the box is not grounded then it gets a bit trickier. If you have a 120v outlet with a known good ground I'd plug a grounded extension cord into that and measure between the extension cord ground and the wire. If no grounded outlet available then you would have to use the neutral (wide blade) of a polarized extension cord. Of course that assumes corect wiring at other outlets which may or may not really be correct.
 
  #7  
Old 01-23-07, 01:58 PM
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Once you determine the hot wire, you will then have to determine which wire leaving is also the hot wire. You will do this by looking further down the circuit, at whatever else is on this circuit, and making sure that the hot wire gets connected properly, same with the neutral.
 
  #8  
Old 01-23-07, 02:01 PM
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Every now and then the neatrul is makred with a paint or tape or the insulation is ribbed .
 
  #9  
Old 01-24-07, 06:28 AM
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Wiring problem

last night I attempted to connect the new lighting fixture. I tried different combinations about a half-dozen times. None of the combinations worked and every time it blew the circuit.
My question is, is it harmful to the circuit to keep blowing it like that? I think I read somewhere that it was so I'm not going to try again,but I'd like to know if it's harmful. Thanks
 
  #10  
Old 01-24-07, 09:46 AM
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You might be at the stage where you need to call an electrician. Harm can be caused on wiring but any answer would be a guess.

Have you tried just connecting the light to the cable that had a live pair of wires? Does that work? Do you have knob and tube wiring? Look in the attic. What do you see?
 
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