54178de2_tings_and_IP_Equivalency_Chart__NEMA_Definition
[NEMA Rating] 13 [IP Equivalent] IP54 [IP Definition] 5 = Protected against dust - Limited to ingress (no harmful deposit) [4] 4 = Protected against water sprayed from all directions - Limited to ingress permitted [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 circulating dust, lint, fibers, and flyings; and against the spraying, splashing, and seepage of water, oil, and noncorrosive coolants.
Rugged Technologies - NEMA Ratings and IP Equivalency Chart
NEMA Definition