EN 60529 outlines an international classification system for the sealing effectiveness of enclosures of electrical equipment against the ingression into the equipment of foreign bodies (i.e. tools, dust, fingers) and moisture. This classification system utilizes the letters “IP”(“Ingress Protection”) followed by two digits.
The first digit of the IP code indicates that equipment is protected against solid foreign bodies intruding into an enclosure. The second digit indicates the degree of protection of the equipment inside the enclosure against the harmful entry of various forms of moisture (e.g. dripping, spraying, submersion, etc.). Due diligence is needed to avoid over specify. See the climatic condition, credibility of accidental fluid / water splash, flammable gas ingress. Do not double dip to have high IP rating box inside a IP rated enclosure.