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How dangerous is rust and corrosion inside an electrical panel?
Friday, January 10, 2020
Corrosion at interior components of an electrical panel creates several safety problems:
1) Circuit breakers are mechanical devices and, like any mechanical device, corrosion can cause it to freeze up and not trip when too much current is flowing in the circuit. This will overheat the wires and possibly start a fire.
2) Aluminum corrodes into a crystalline white powder and, although aluminum is an excellent conductor, aluminum oxide is an insulator. An example of corrosion forming at aluminum bus bars, along with rust stains, is shown below.
Anti-oxidant paste is required to be applied over exposed aluminum wire at connection lugs in a panel. But, if that is not done or excessive moisture attacks the aluminum, the wiring can overheat and start a fire. A demonstration is shown in the video below.
3) Although corrosion can occur inside a panel due to a humid environment, most panels with severe corrosion of the internal components have a defect that allows water to drip down through the panel box. Rust at bottom of the interior is a sure sign of water intrusion, and the water draining through the panel box can also cause an electrical short and fire. One common way that water enters a service panel is when the cap piece on the weatherhead at the top of the service mast goes missing, like in the photo at right. Water goes straight down to the top of the box in many cases.