Black film on aluminum wiring


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Old 03-11-08, 12:06 PM
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Black film on aluminum wiring

I'm taking out an interior wall in a 1970's house, and when I opened up the drywall I noticed a brown/black film on the wiring about half way up the wall (the wiring near the outlets are white). It only appears on the aluminum wiring. And the framing doesn't have any marks on it.

Any ideas what may have caused this?

Thanks
 
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Old 03-11-08, 12:46 PM
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Is it on the aluminum itself or on the outer sheath of the cable? Is the skin of the cable scraped or cut? It would be great if you could post a picture using a photo sharing service.
 
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Old 03-11-08, 01:02 PM
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Sorry for the confusion. It's on the outer sheath of the wire, and it only seems to be on the side not again the stud. I'll post a picture when I get home from work.
 
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Old 03-11-08, 04:06 PM
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If the insulation is intact then it sounds like some dirt or grease that was on the cable when installed. Aluminum connections need an anti-oxidant paste applied to the connections. Perhaps the installer just had dirty hands when pulling the cables.
 
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Old 03-11-08, 05:59 PM
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Soaping NM cable was common at one point. I have done it myself in recent times. If it is jute or or cloth sheathing I have seen what you descibe. I dont know if it is soap or the sheathing is wax impregnated or what. I would be way more worried about the AL wiring period. If you got walls open and can get at it, yard all that AL wire out while it is exposed.
 
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Old 03-11-08, 09:43 PM
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Just to clarify I am pulling out the AL wiring, I was wondering if I should be pulling all the wiring in the house. Here are 2 pictures of it. In the second picture I've wiped off some of the film with my finger.


 
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Old 03-11-08, 10:02 PM
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Is your area flood prone?
 
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Old 03-11-08, 10:35 PM
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There was some signs of water coming through the foundation in the basement, but this wall is on the main floor, and well away from anywhere that could leak. The roof was replaced recently, although I don't see signs of water on any of the studs or plates. What are you thinking? Mould?
 
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Old 03-11-08, 11:54 PM
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I have to agree with Joed.

The original installer got sloppy with the "NO-OX" . Is it sorta Greasy?
 
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Old 03-12-08, 10:36 AM
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I wouldn't say it's greasy, more sticky than anything. It sort of balls up when I rub it off. But I'm not really sure what 30 year old grease would be like.

My initial concern was because it looked like the sheathing had been burnt, but I'm pretty sure that isn't the case here.

Thanks for the help
 
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Old 03-12-08, 12:40 PM
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It looks like some smoke was flowing in that wall cavity. The wires aren't burn but maybe something else did at one time. Is it only on the wires? Maybe the wires were salvaged form a fire??
 
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Old 03-13-08, 11:42 AM
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It is only on the wires, and it's only on those AL ones. There are some old copper ones that are fine. There's also nothing on the studs or drywall that indicate that there was a fire.
 
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Old 03-13-08, 02:27 PM
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CArefully!!!!!!!Look inside your breaker panel.....Dont touch anything!!!!

There should be some of this Black/ Brownish substance on the incoming service wires where they meet the Main breaker or Buss. Is it the same stuff that is on your wires?

I could concievably imagine that "NO-OX" could be "Sticky" after 30 years.
 
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Old 03-13-08, 03:35 PM
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If the insulation is not damaged then don't worry about it. It still think it was there on install.
Or better yet being aluminum just pull it out and replace with copper.
 
 

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