There are two widely used standards. The national standard for enclosures in the US was established by NEMA (National Electric Manufacturer Association), the international standard for enclosures was established by IEC (International Electric Codes) In today’s international trade world, we see quit often both standards mentioned on a product. (Example: NEMA 4X / IP 65)
Common NEMA enclosures types:
IP codes (Ingress Protection Codes)
IEC outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the intrusion into the equipment of foreign bodies (i.e. tools, fingers, dust) and moisture. This classification utilizes the letters IP (Ingress Protection) followed by two digits (example: IP 64).
The first digit indicates the degree that persons are protected against contact with moving parts (other than rotating shafts) and the degree that equipment is protected against solid bodies intruding into an enclosure.
The second digit indicates the degree of protection of the equipment inside the enclosure against harmful entry of various forms of moisture (i.e. submersion, dripping, spraying).
1st digit (Protection from solid objects intruding the enclosure)
2nd digit (Protection from moisture)