The IP rating is a classification given to the casings and enclosures of electrical apparatus (e.g. luminaires, LED modules and control systems), to determine their suitability for the environmental conditions in which they will be used.
The purpose of the standard is to offer a defined grading system, rather than abstract terms such as 'strong', 'water resistant' and 'dust proof'.
IP stands for Ingress Protection, but is also interpreted as International Protection or Index of Protection. It is published by the International Electrotechnical Commission (IEC) which is a global organisation that determines the standards for all electrical and electronic technologies.
The ratings take the form of two digit codes which classify the degree of protection against intrusion from dust, accidental contact and water.
The first number gives the degree of protection against the penetration of solid objects into the enclosure. The second number gives the degree of protection against water and moisture penetration.
A light with an enclosure classified as IP68, will be ‘dust-tight' and protected against long periods of submersion in water (maximum depth and duration specified by the manufacturer).