So my client and his father-in-law are both electricians, and we were all wondering what was going on with a generator panel.
They had an old panel and breakers. The branch wiring they used to the generator panel and all the breakers were multi-strand AL -12/2, but all the branch wiring was copper, single strand 12/2. All the wire caps were AL CU mix without the proper caps.
Every time the heating unit turned on (which had a 20 amp breaker with the multi-strand AL) it would make a loud humming noise.
There was more to it, but that’s the gist. Any help explaining if its good, bad, or what the heck is going on is appreciated. My clients were scratching their heads a bit. Thanks!