54178de2_tings_and_IP_Equivalency_Chart__NEMA_Definition
[NEMA Rating] 12 and 12K [IP Equivalent] IP52 [IP Definition] 5 = Protected against dust - Limited to ingress (no harmful deposit) [4] 2 = Protected against direct sprays of water up to 15° from the vertical. [NEMA Definition] 
Enclosures constructed (without knockouts) for indoor use to provide a degree of protection to personnel against incidental contact with the enclosed equipment; to provide a degree of protection against falling dirt; against circulating dust, lint, fibers, and flying; and against dripping and light splashing of liquids
Rugged Technologies - NEMA Ratings and IP Equivalency Chart
NEMA Definition