Idunno said:
If there is no source of electricity in the safe then would there be a potential for stray current? If there's no stray current traveling from the safe to the ground then do you need to worry about cathodic protection? It's a safe, not a subway train drawing DC power from a third rail and losing stray return current to the ground, weakening the rails. Even if there was current moving towards the ground, wouldn't the steel bolts used to bolt it to the cement floor serve as the anode?
I'm no expert on the subject for sure but a circuit is created and galvanic corrosion occurs when you have two dissimilar metals present and an electrolyte to complete the circuit. So even though the safe doesn't have a power source, the fact that it is made of steel (iron) which is a relatively active metal and likely will be in the presence of water and possibly salt too there is a very good chance it will lose electrons to the environment which will cause it to rust. Of course a good protective layer (paint in this case) is the first level of defense against rust but in my case I had to "walk" my safe into place on my concrete floor so it is likely that some of the paint is missing on the bottom of the safe. Since I live in Northern NY and during the winter my garage floor is usually covered with water from melting snow with road salt present in the slushy mix, the corrosive environment is present for rust to occur. I can't paint the bottom of my safe, nor do i think putting it on a non-conducting surface would help since I can have over an inch of water on the floor at times; I decided to go with the galvanic cathodic protection approach. What I figure is if the paint on the bottom of the safe has been scrapped off during the move, by putting it on aluminum plates I force the safe to be the cathode since aluminum is more active than iron. So what should happen when the safe is exposed to the salt water is my aluminum plate shims should corrode as a sacrificial anode and transfer electrons to the safe and environment preventing the safe from rusting. Over time I will need to clean and/or replace the aluminum plates but hopefully the safe will remain rust free.