Rust-colored residue in electric panel

I’m still a fairly new inspector, so apologize for the question: I’ve encountered a few electric panels that have a rust-colored powdery residue on the plastic portion of the breakers. It is easily cleaned off. Not sure if the cause is moisture, heat or something else. Please help.

Posting a picture is helpful for others to understand more fully…:slight_smile:

Where are you from/ Not that it matters with whats going on but it might help explain somethings.

Electrical arching creates a brown power stain. A picture is in order here.


What did you report on the other panels that had the issue?