wire corrosion?

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Old 05-16-18, 07:36 AM
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wire corrosion?

Hunting down minor dimming/flicker so I was remaking some connections in my attic. I noticed some of the joints had a whiteish/greenish corrosion on the wires under the wirenuts. It wasnt all that bad but it was obvious a portion of the joint was corroded. Will see if that was the source of the issue but I was wondering....

does this white/greenish corrosion indicate a bad connection or is that the normal patina of copper? Sorry I dont have a photo for you.
 
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Old 05-16-18, 08:56 AM
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Sounds like moisture got in the connection? I would clean the connections and use a new wire nut.
 
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Old 05-16-18, 10:08 AM
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Does heat cause that green and white too?
Is that type of corrosion conductive or could it be the cause of the dimming/flicker?

But it is likely moisture, its in a junction box directly above my bathroom and the exhaust fan in an untreated attic space. I pulled new wire in the box for another reason and many flakes of rust came out of the emt. I noticed the same thing a long time ago in another circuit.

Would plugging the holes of the pipes into that box with duct seal be a good idea?
 
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Old 05-16-18, 01:00 PM
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Corroded wires have less conductivity than clean ones. That means higher resistance in the connections and overall worse connection quality. It can cause flickering and excess heat build up.

Any conduit that goes between a heated/cooled space and an unconditioned space should be stopped with duct seal putty. It's now required by modern code but most old ones are not sealed.
 
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Old 05-16-18, 01:55 PM
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In the boxes in question, I checked and remade any suspect joints. I then sealed off the conduit openings the best I could with duct seal. Did this in the attic and the boxes below. I also put those foam insulation inserts under the cover plates. Hopefully I wont have to do anything further.

QUESTION:
If I had only sealed off one end of the pipe, would that work too?

Im kind of thinking even one side would be beneficial since it would stop airflow.
 
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Old 05-16-18, 03:17 PM
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One end should be enough . You just want to stop the transfer from warmer areas to the colder areas to cut down on condensation .
 
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Old 05-17-18, 06:53 AM
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I also tucked R30 around the box in question and rolled it out over the conduits. I dont know if that will do any good....

Looking at the rest of the exposed conduit in the attic I can tell it could get quite expensive to do the rest of them in this manner. Its been this way for 60 years.

FWIW the attic is insulated ok, there is batting between joists and blown in on top of it. The conduit and boxes did not get covered by the added layer of blown-in. I have no complaints about warmth in the home that would make me think I need more.


Would you be thinking of insulating the rest of the conduits in the attic in this manner? Or is this throwing money into the pit?
 
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