aluminum supply to sub panel - breaker tripping/wire heating
I have a 100 amp circuit going to a subpanel in the basement. It's worked fine until this week. the 100amp circuit has become very prone to tripping, especially when the dryer in the basement has been running for a bit. The house was built in 1994.
I removed the panel cover for the main panel and noticed quite a bit of thermal build-up beginning @ the breaker and going for about 6" up the aluminum wire that feeds the basement subpanel. My first theory is, of course, oxidation. I have not pulled the aluminum wires from the breaker to see if there is oxidation, but I can see that an oxidation-inhibitor was applied to the other aluminum in the panel.
I did not detect similar heat build up at the subpanel.
So, here are the questions:
If I do a visual inspection of the wires and find that there is oxidation, there is not enough slack in the wire to cut back more than 1" - I doubt that would be enough. Is there any way of installing a connecting block in the panel as a "splice" that would meet code? Maybe run copper from the block to the breaker? I'd really hate to replace the whole run (I'm guessing 70 feet) it would be quite expensive.
should I replace the breaker itself? I would guess that it has oxidation on it as well.
If a visual inspection does not reveal oxidation, what would you recommend as the next step in diagnosis?