Southern Calif. House built in 1981. Ground wire looks like it is
of Aluminum…Two Breakers seem also to be connected by aluminum
wiring…All other wires in the panel were copper. (including the service wires: 100 amp)
No defects detected…all branch circuits it the house worked.
If the breaker was not rated for AL, that would be a problem, but it appears to be a two-pole Bryant. Most breakers are rated for AL and CU.
The AL wire that we are concerned with is the solid-strand AL, usually 12 AWG to 8 AWG used for distribution (H/N) of the branch circuits. In other words - current carrying conductors.
Larger AL and stranded AL are generally not a concern.