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#221586 09/22/21 12:18 AM
Joined: Mar 2005
Posts: 237
I have a question regarding neutrals in a residential panel that are extremely discolored as well as the neutral bus jumper.

I am wording this as a code question pertaining to anti I am wondering what thoughts you guys have on this. The electrical sub-panel (main is on the 200 amp meter) in question is a fairly new Cutler Hammer CH, with arc fault breakers and is located in Texas.

Would failure to use antioxident on aluminum wires per NEC have anything to do with the discoloring?
Perhaps loose neutral in panel, however that would that probably just throw 240 volts across circuits and wipe out a bunch of stuff?

My brother-in-law was told by electrician that it could be from a lightning surge protection, this is the second time a breaker was replaced due to tripping by the same electrician who pointed out the discoloring on neutral bus jumper on his first trip.

Lastly, I think a megger test on all his home runs would be prudent...what say you?

Thanks in advance.

2017 / 2014 NEC & Related Books and Study Guides
Joined: Jul 2004
Posts: 9,667
Likes: 5
I doubt the lack of paste did anything if the lugs were properly torqued. There was a study (Georgia Power research center) that showed aluminum wire in an aluminum lug was better than copper in that lug. The paste made no difference at all.
110.3(B) really doesn't enter into it unless you can find a manufacturer that "requires" the paste. Simply "recommending" it doesn't count.

Greg Fretwell
Joined: Apr 2002
Posts: 7,282
Likes: 3
Hey h2o
Welcome back, it’s been a while

My two cents….
The discoloration is from heat. Heat is more than likely from “bad” terminations. The branch circuit neutrals may have been cooking in the panel that was replaced, but you mention the neutral jumper buss is discolored ( loose connection)??

As to Pentrox, the Code does not mention it. It is more of a trade workmanship item, and IMHO would not be a direct cause of the heat. Think about the buss jumper.

Stay safe, and please don’t be a stranger here!


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