Humidity is humidity...it goes everywhere. I have seen ferrous steel
corrode in the supposedly "driest" places on a boat that would never corrode in a house. I tend to disagree. I think it is the microscopic salt
particles in the air that does the damage anywhere on a boat. I use tinned wire everywhere in addition to adding Tef-gel at all terminations.
Ever see what happens to any type of steel electrical
boxes that people mistakenly put aboard their boat after a few years...they turn to rust. Does the same thing happen in a house away from the salt