I had a sub-panel with a loose neutral wire that caused substantial arcing between the wire and bus bar. Arcing generates a staggering amount of heat (thousands of degrees in either F or C) and in this case, it literally melted one of the wires clean through! See here. This is obviously very bad and it resulted in me replacing the entire panel and everything in it.
But electrical arcs are typically feared not because they result in having to replace panels and breakers and such but because they can (and do) cause fires. That makes complete sense for arcing in outlet boxes or inside walls or through attics and the like. The arc results in temperatures far beyond what is needed for wood to ignite and so fire is almost inevitable in some cases.
What I don't understand is how electrical arcs can cause a fire in an electrical panel.
The panel is steel and everything inside it will either be steel, copper, aluminum, or some kind of plastic that melts or chars but doesn't burn. In fact, I can't think of anything in a panel that even could catch fire.
Is it because the panel itself gets hot enough to ignite the wood framing touching it? In my case, the panel certainly was hot to touch -- but not so hot that I couldn't keep my hand on it. That is, not even remotely close to the ignition temperature of any building material I can think of.
What am I missing? How does an arc inside a steel panel cause any sort of fire?
