I need to mount a drive inside an enclosure in a semi-outdoor location (under a covered awning). It will not be fully exposed to the elements, but during harsh weather it could be exposed to some moisture. Would it be safe to use a NEMA12 type enclosure for this application?
Even though your enclosure would not be exposed to the elements most of the time, I would still recommend going with a NEMA3 or NEMA4 enclosure. NEMA12 is intended for indoor use while NEMA3 & NEMA4 are designed for outdoor use and provide protection against weather hazards such as rain and sleet.