Here is a good example of how bad equipment can get without regular cleaning, operating and testing (which does have drastic effects on arc flash results and unscheduled downtime is something most plants don't like).
I was called out to find out why a company's OCB was single phasing on them and to take neccessary actions. After we lowwered the tank, the reason was rather obvious...

That's certainly something, that I've never seen, even after a few hundred ocb inspections and rebuilds!