The IP rating, or International Protection Marking as it technically known is part of the IEC standard 60529. It is sometimes interpreted as Ingress Protection Marking, but its job is to classify and rate the degree of protection provided against intrusion (body parts such as hands and fingers), dust, accidental contact, and water by mechanical casings and electrical enclosures. It is published by the International Electrotechnical Commission (IEC). The equivalent British standard is EN 60529.
IP Ratings,Water-proofing