Overheating of a circuit or breaker under some circumstances will cause a burn type odor, or have visual evidence of overheating. Overloaded circuits, power surges, and arc-faulting are common reasons for this to occur.
A defective breaker, may sometimes be responsible for this condition to occur. Breakers are inexpensive and any defective breakers should be replaced.
Corrosion and moisture
Corrosion on a panel’s busbars may result in overheating, due to a faulty or incomplete connection of the breaker to the busbars.
Electrical panels that get moisture in them or ones that are subject to moist air, are more likely to develop corrosion. Also, homes whose basements have damp air and the panel is located in the basement, may experience corrosion and rust.
These moist areas may also cause other electrical boxes to have corrosion or rust.
Who to consult? An electrician.
Replacing defective or damaged breakers with burn marks can easily be done by an electrician. At times the electrician may need to trouble shoot the cause.