Where I'm at we'd have to use EMT for a wiring meathod becauase of local amendments. Your Building Dept. could tell you if it's different from NEC.
As for wheather proof, it's not required if under a roof or covered. I can't find the code though.
Safetygem,
I thought you were going for classified until I looked it up.
So here's my take:
547.1(A) is conditional. It says where there's exessive dust.
And I don't know if a horse is livestock. Don't you eat livestock?
Is there a need for GFCI?
