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This is one of those situations where the actual problem "came out in the wash" — that is, there is no way for an inspector to determine that this type of deterioration would occur at the time of the original final inspection. However, we can clearly see this is a violation of 110.11, which in part states, "Unless identified for use in the operating environment, no conductors or equipment shall be located in damp or wet locations; where exposed to gases, fumes, vapors, liquids, or other agents that have a deteriorating effect on the conductors or equipment; or where exposed to excessive temperatures."
Further analysis reveals this service equipment is located indoors and is fed from an overhead service. Maybe if the installer had sealed the raceways as required by 300.5(G) — which is only specifically applicable to underground applications — then, quite possibly, the equipment would not have ended up in this state. Although the requirements of 230.53 call for service raceways to be "arranged to drain," I'm quite certain the Code writers did not intend for them to drain into the service equipment.
Due to the nature of enforcement, unless an inspector were to see the condition of this service switch during the course of an inspection on another part of the premises, there really is no means available to require the property owner to replace this deteriorated equipment. And, as we all know, trying to tell the property owner that his service equipment is in bad repair is like trying to tell your buddy that his sister is not attractive. They just don't see it, and are offended by your suggestion.