Ceiling light wiring help

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  #1  
Old 12-13-15, 01:08 PM
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Ceiling light wiring help

recently we decided to replace ceiling fixture with led fixture. Upon removing old fixture we found two black wires on one side of junction box and three wires red-brown-black on other. The house uses fuses. We used tester and found that the two black wires created a 120 volt power source but when attached to the black wire on new fixture and black wire from other side we still got nothing and blew the fuse what am I doing wrong? All suggestions would be helpful Thank You
 
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  #2  
Old 12-13-15, 01:16 PM
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oops forgot vital point!!

the two wires CONNECTED create 120 volts but SEPERATE they create zero volts
 
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Old 12-13-15, 01:29 PM
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Which wires were the old fixture connected to?
 
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Old 12-13-15, 01:36 PM
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We used tester
Do you mean a multimeter?
the two wires CONNECTED create 120 volts
That would be a dead short and blow the fuse. If you are using a non contact tester it can not be used to determine if you really have 120 volts.
two black wires on one side of junction box and three wires red-brown-black on other
Since you are in Buffalo I'm guessing conduit not cable. There should be a white wire in the box. Often with aged wiring newbies to electrical will think an aged white is some color other than white. I suspect the so called brown is closer to tan and is really your white. If you don't mind doing a smoke test connect the blacks together and connect your light to red and white (what you called brown). Do your connections with the fuse removed. Then screw an incandescent bulb into the fuse holder. If the bulb just dimly lights then remove and reinstall the fuse. If the bulb lights at full brightness do not install the fuse.
 

Last edited by ray2047; 12-13-15 at 01:53 PM.
  #5  
Old 12-13-15, 01:38 PM
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Where are you located? US, or other? You did take a picture of how it was wired before you took it down, didn't you? Oops. Take a picture of the box with the wires hanging down so we can see it all. Also take a picture of the switch box with the switch pulled from the box. Remove the power first and post the pictures. http://www.doityourself.com/forum/el...your-post.html
 
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Old 12-13-15, 02:33 PM
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Larry, the poster has shuffled off to Buffalo.
 
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Old 12-13-15, 02:55 PM
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yes a multimeter but without alligator clips just hand held sensors, and also I'm a little beyond taking pictures to keep track. ok so then the wire colors are red-white and black. ok so I guess what I am asking is to figure out which of the two black wires is sending power to the switch because ive tried these combos:
one black connected to two black (from junction box) then connected to fixture black and one black connected to white then connected to fixture white .
is their another way.
as for using the multimeter I touched the black wires simultaneously one to the red sensor and one to the black sensor that is when I got the 120 reading. When I touched only one there was no reading at all
 
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Old 12-13-15, 03:01 PM
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I am asking is to figure out which of the two black wires is sending power to the switch because ive tried these combos
Probably neither. Probably both are power out. Power probably goes in at the switch then out to the light as a constant hot black and a switched red.

yes a multimeter but without alligator clips just hand held sensors
Multimeters usually just have probes. Sensors if you mean non contact testers should be given to your kid to play with while you work.

Did you read my test connection? If so and want to be cautious use your multimeter to measure voltage between the alleged brown wire and the black wire in the same conduit. Red to "brown" should show ~120 volts only with the switch on.
 
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Old 12-13-15, 03:16 PM
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pardon my ignorance in terminology but yes PROBES . If I do the afore mentioned "smoke test" and bulb is dimly lit what exactly does that tell me? In the same instance if it is brightly lit what does that tell me.
 
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Old 12-13-15, 03:42 PM
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If I do the afore mentioned "smoke test" and bulb is dimly lit what exactly does that tell me? In the same instance if it is brightly lit what does that tell me.
Full bright indicates your connection has created a short. Dim indicates no short and it is safe to screw in the fuse.
 
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