Stripping aluminum for breaker

[Whiskeymike]

I had a 60 amp double breaker go bad tonight. It was arcing inside every 10 seconds or so. Anyways, I picked up a replacement and when I was trying to unscrew the clamps on the output, I could not get either screw to budge. I tried multiple screw drivers it was starting to strip the head. There was enough slack in the aluminum wire, so I cut them at the breaker and stripped the sheathing back. On the outside of the wire was a white coating. As first I thought it was sheathing, but it was more like a coating. I ended up scraping it off with a razor until it was shiney. I don’t think it was oxide. It was turning dark, so I couldn’t grab a photo.

Was I correct in doing that? Is there a correct way of getting rid of that?

Also, any idea why the screws were impossible to back out? Seize because of time/crud?

 

[trbomax]

If anti-ox paste was used on the wire and clamp,this would not be an issue.The paste should be rubbed into the wire strands well.

 

[tyme2par4]

aluminum oxide is a white powder, so that sounds like what it was. Typically it is recommended to brush the conductor with a wire brush, then apply anti-ox paste when you terminate.
The razor probably did a fine job as long as you didn't damage the strands too much.

 

[Aceman]

I had a 60 amp double breaker go bad tonight. It was arcing inside every 10 seconds or so. Anyways, I picked up a replacement and when I was trying to unscrew the clamps on the output, I could not get either screw to budge. I tried multiple screw drivers it was starting to strip the head. There was enough slack in the aluminum wire, so I cut them at the breaker and stripped the sheathing back. On the outside of the wire was a white coating. As first I thought it was sheathing, but it was more like a coating. I ended up scraping it off with a razor until it was shiney. I don’t think it was oxide. It was turning dark, so I couldn’t grab a photo.

Was I correct in doing that? Is there a correct way of getting rid of that?

Also, any idea why the screws were impossible to back out? Seize because of time/crud?

If it was like white chalk, that's corrosion.

If it was thin membrane of white plastic between the aluminum conductor and the overall outer insulation, some aluminum wire comes like that, typically USE.