54178de2_tings_and_IP_Equivalency_Chart__NEMA_Definition
[NEMA Rating] 5 [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 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 settling airborne dust, lint, fibers, and flyings; and to provide a degree of protection against dripping and light splashing of liquids.
Rugged Technologies - NEMA Ratings and IP Equivalency Chart
NEMA Definition