# Need help diagnosing lighting circuit



## kroppe (May 7, 2000)

Hello, 

I am trying to install a new dining room chandelier. The old one was working fine, until it died. I can't say exactly what the cause was for the old fixture to fail. 

I have installed the new fixture and can't get it to work. There are two switches feeding the fixture, one is a dimmer and one is a toggle. The fixture has two brown wires, and one copper wire. I attached the copper wire to the green screw on the ferrule crossbar. One brown wire is connected to black in the ceiling box, the other brown wire is attached to white in the ceiling box. In the ceiling box are two red wires connected to each other. I have not done anything with the red wires. 

I have verified 120V to the white and black wires, and the fixture does not light. When the switch to the fixture is turned off, there is still 60-62 Volts across the black and white wires. Is this normal? 

I have verified continuity between one brown wire and the bulb holder female base, and continuity between the other brown wire and the male tang at the bottom of the bulb holder. 

There are no breakers out of position at the panel. I reset the relevant breaker back and forth, just to be sure. 

What are my next steps to diagnose this? Can one of the switches be bad, even if I am reading 120V at the black and white wires? Thanks for any input. 

p.s. I searched this site, another DIY site and Google and didn't find an answer.


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## ih772 (Jan 28, 2003)

It also sounds like you are missing the white neutral wire in the fixture. Temporarily connect both brown colored wires to the black wire in the ceiling box and connect the white from the fixture (when u find it) to the white wire in the ceiling box. If the fixture works at that point you should separate the brown colored wires and put the one you want dimmed on the dimmer.


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## jpollman (Jan 14, 2001)

I'd bet that it's one of the switches that failed, not the fixture. If you have two switches servicing the fixture, they are three-way switches. (there will be three screw terminals on each switch, not two)

You need to find out which switch and box is supplying power to the circuit. Once you've identified that, it should be an easy fix. Do a search and find a wiring diagram for a three way circuit. When you've identified the line supplying the circuit you should be able to figure it out. 

If it was working before, you've got the correct type of switches/dimmers installed. I'd bet that the dimmer just went bad. When replacing a switch in a 3-way circuit, make sure that you replace them with 3-way switches and you have to identify the common terminal in order to replace it correctly. If you just place the wires on the new switch in the same location they were on the old switch, it may not work. That's because the common terminal may be in a different location on the new switch.

Here's a link to one of MANY diagrams available.

http://www.electrical-online.com/3waydiagram/


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## Treehopper (Aug 18, 2007)

...what he said!


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## kroppe (May 7, 2000)

Thanks guys. I looked again and there are no other wires from the fixture except for the bare coppe ground and the two brown wires, which are actually molded together like lamp cord. To be sure, I disconnected the two browns, reversed them, and it still doesn't work. There is no white from the fixture.

My suspicion is the dimmer switch is bad. It is a 30-ish year old Lutron and I have felt it get warm a few times. I'll put in a new one tomorrow and see what happens.


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## jpollman (Jan 14, 2001)

I'm willing to bet that it's the dimmer. The fixture end is simple and probably no problem there. Just if it's a 30 year old dimmer, pick up a new one and give it a try. Just make sure you get a three-way dimmer! When it comes to putting it in, just make sure to identify the "common" terminal on the old one. It will probably be labeled. Make sure the wire going to the common on the old one gets put on the common terminal on the new one. The other two wires are "travelers" and it doesn't matter which one goes where.


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## ibthetrout (Sep 24, 2003)

Chiming a little late here....

He said he had 120v across the brown wires so I don't see how it's the dimmer unless it will not cut off the power when switched off. What you are describing is a 3 way light circuit. It uses 2 switches to control one device/light. The 60-62 volts you spoke of is most likely stray electrical voltage generated by amount of wire for that circuit passing through the earths magnetic field. It most likely has nearly zero current but 60 volts. I ran into this one time. This part I DO NOT SUGGEST ANYONE DO!. I got brave in that situation and actually grabbed the wires....no shock......glad I was right about that one, but I'll never do it again.

If you have 120v across those brown wires then that light should turn on and if it doesn't it's the light fixture. If you can't get 120v across the brown wires then it is probably one of the switches (assuming you did not mess with any of the wiring at the switch boxes).


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## ih772 (Jan 28, 2003)

Brown wires molded together, that's an important detail you accidentally left out. Follow the zip cord in the fixture and see which wire connects to the threaded metal portion of the socket, that is the neutral connection.


Turn the dimmer fully on or fully off and see if the roughly 60V goes away or increases to 120V.


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## .270rem (Nov 18, 2009)

if you have those new style bulbs (mercury ones) they wont work on dimmers.


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## kroppe (May 7, 2000)

Thanks for all the input folks. It was the dimmer. I installed a new 3-way Lutron and the fixture works. I left the other 3-way toggle, and will replace it if/when it needs to be replaced.


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