Interesting topic, John,
There is a galvanic chart around somewhere, I saw it some years back, it shows which metals will corrode when placed with other metals and to what degree, this is, I might add, first year apprentice electrical theory.
Having said that, I work in an environment (dairy sheds) where anything is either PVC, stainless steel or heavily galvanised steel pipe.
Anything that even remotely touches concrete, is always stainless.
I remember back when PVC enclosures became prolific in the trade here, some you bought would last quite well out in the weather, some just fell to bits, due to the sunlight, thankfully most of them problems have since been ironed out.
