There is corrosion at the exterior main panel lugs/bar.
In my second year of inspections and have yet to see this.
Assuming it’s from moisture getting into panel. Planning to recommend lic electrician evaluate before close.
Any other tips, explanations, comments are welcomed.
…AND REPAIR AS NECESSARY!!
Galvanic corrosion - Wikipedia
As Jeff stated above, it’s a defect that should be addressed.
Moisture that enters a circuit breaker panel can corrode electrical
wiring, connections, circuit breakers and even rust the bottom and
inside of the panel box.
Deterioration, rust, and corrosion in an electrical connection create
extra resistance to electricity flow, and consequently heat.
In severe cases, electrical arcing and excess heating can occur inside the
panel causing a fire hazard.
No approved method exists for removing/cleaning corrosion or
contaminants from panel interiors or components such as bus or
terminal bars, circuit breakers or fuses.
The panel and/or components inside may need replacing.