"If the meter dial rusts to a stop but the conductors keep conducting, is the electricity free?"
Meter parts are usually aluminum and various alloys, and the bearings are usually magnetic suspension nowadays, I think. It would be hard to envision one rusting to a stop, although you could adversely affect the accuracy. If any salt water got in there, corrosion would be the least of your problems.
In areas around Galevston TX the primary (7200V)and secondary (120/240V)lines are buried but the transformer is mounted on a pole. No pad mounts are used. You see poles thru out the area with no wires between. This is to prevent damage durring tidal flooding.
