Aluminum Wire?

I came across this wire in a panel yesterday. It is for a 60 year old home that the wiring had been completely done. All the wires were changed except for this one wire from the furnace. I would imagine the copper / aluminum connection would be the problem at the breaker.

Am I on the right track?

It is more likely to be tinned copper and not aluminum.

Aluminum wire was more often used from the mid '60s to the mid '70s when copper prices spiked.


Notice the thickness and type of insulation on it.

Without a doubt. Tinned copper.

Thanks so much for the quick reply!

This is aluminum wiring: