junction box: interior coated in soot

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  #1  
Old 04-08-14, 03:45 AM
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junction box: interior coated in soot

I noticed that one hot wire has melted to the copper where it touched I assume a neutral wire because that is the impression left in hot wire. I don't see any other wires melted.; cables with paper insulation. I also noticed sparks when the nut from hot wire touched uninsulated neutral wire.

Is this normal. I assume there was nick in hot wire to start this.

3inch steel junction box. 5 cables. 5 white. 5 black. 2 red. Not sure of gauge.

Directly serves fluorescent light. Switch for fluorescent light. Plug for microwave. Line light.
 
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Old 04-08-14, 04:03 AM
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No it is not normal. The box has too many cables in it. Is it readily accessible, say in an attic? It would be best to redistribute the cables into multiple junction boxes, relieving the cramped conditions, and allow you to get back to good eire on each cable. Had a similar problem on a remodel. 9 cables in uncovered 4" boxes jist twisted and taped. Real breath grabber.

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  #3  
Old 04-08-14, 05:39 AM
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Be sure to label each individual wire end and make notes about how everything was connected before disconnecting anything or removing any cables from the box.

Inspect and double check each wire. Any melted or burned or significantly nicked wire including ground wire has to be snipped off and if needed new copper exposed to remake connections with. The wire ends need to be long enough for six inches of each to extend into the box.

If the old box is still used for anything, wipe off all of the soot inside. You can get an extension ring to fit over the mouth of the box and provide more "space inside." The existing wires and cables would have required a box of at least 32 cubic inches (for 12 gauge wire). (12 wire ends plus one point for all the box clamps and one point for all the ground wires times 2-1/4 ci per point)
 
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Old 04-08-14, 05:50 AM
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Twist

I see that the bundle of ground wires are twisted left-handed. I wonder about the wire nuts?
 
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Old 04-08-14, 05:53 AM
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In the example pictured (not the OP's) there were no wire nuts originally. That box would have had to be re-made-up with right handed twists for wire nuts or (if one insisted) 3/4" or whatever straight wire ends going into Ideal or similar push-in clips.

A crimp ring could also be used on the ground wires as-is.

Just twisting with tape is not good enough nowadays for making connections although ground wires simply twisted have been used at least into the 1980's.

Sometimes a wire nut will go onto left twisted wires satisfactorily but that is hit or miss and not recommended for the amateur to try. It depends if coincidentally the proper compression force is reached before the wire ends deform and the wire cluster swells from untwisting forces.
 
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Old 04-08-14, 07:30 AM
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The picture posted here is Chandlers and from one of his jobs. It's not the original posters.
 
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Old 04-08-14, 12:57 PM
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Just twist and electrical tape, which had, over the years lost much of its glue. I don't even think I could have put a blue b cap on them even if they were twisted properly. That's 9 #12 old color sheath.
 
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Old 04-08-14, 05:45 PM
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Thanks, guys. Do you agree that a nick in hot wire was enough to cause so much soot? I don't think it touched bare ground. Four neutrals are spliced together and the other neutral wire is used as hot wire. Ie one cable is all hot. I noticed that two ccts run through junction box so if
I have neutrals spliced together from two ccts do I have too much current or just heat at that point. The splicing and connections look professional.
 
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Old 04-08-14, 06:04 PM
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the other neutral wire is used as hot wire.
Then it isn't a neutral. Just because a wire is white does not make it a neutral.
Do you agree that a nick in hot wire was enough to cause so much soot?
You wouldn't get soot even if it was bare unless it touched a grounded conductor.
do I have too much current or just heat at that point.
Too much current will trip a breaker. You shouldn't have too much heat.
Plug for microwave
If it is in the kitchen the lights should not be on the same circuit as the receptacle.
 
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Old 04-08-14, 06:11 PM
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if I have neutrals spliced together from two ccts do I have too much current or just heat at that point. The splicing and connections look professional.
No, but you do have a code violation. The neutral for each circuit must be kept with that circuit and only that circuit. In fact, I'm not sure it would even work.

The only exception to this is a multiwire branch circuit, and that isn't really an exception. It's a different wiring method where one neutral is serving two hots. Is that what you have here?
 
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Old 04-09-14, 02:36 AM
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http://i36.photobucket.com/albums/e2...8/wires002.jpg

http://i36.photobucket.com/albums/e2...edwhite005.jpg

white wire was stripped too much and not covered so i dont trust this anymore. thanks again. i will
redo this mess. i know the paper insulation burned but not sure what caused the ignition.
 
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Old 04-09-14, 11:51 AM
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Soot in a box can also be from air movement.
 
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