What do IP Rating and NEMA Rating stand for?

The IP Rating (Ingress Protection Rating) of an instrument consists of the letters IP followed by two digits and an optional letter. As defined in international standard IEC 60529, it classifies the degrees of protection provided against the intrusion of solid objects including body parts like hands and fingers, dust, and accidental contact (the first digit after IP), and water (the second digit after IP) in electrical enclosures.

First digit: Solid particle protection

Digit	Protection against solids
0	No Protection
1	Protected against solid objects up to 50mm e.g. accidental touch by hands
2	Protected against solid objects up to 12mm e.g. fingers
3	Protected against solid objects over 2.5mm e.g. tools
4	Protected against solid objects over 1mm e.g. wires
5	Protected against dust - limited ingress (no harmful deposit)
6	Totally protected against dust

Second digit: Liquid ingress protection

Digit	Protection against liquids
0	No Protection
1	Protected against vertically falling drops of water e.g. condensation
2	Protected against direct sprays of water up to 15 deg from the vertical
3	Protected against direct sprays of water up to 60 deg from the vertical
4	Protected against water sprayed from all directions - limited ingress permitted
5	Protected against low pressure jets of water from all directions - limited ingress permitted
6	Protected against strong jets of water e.g. for use on shipdecks - limited ingress permitted
7	Protected against the affects of immersion between 15cm and 1m
8	Protected against long periods of immersion under pressure

NEMA Rating

The National Electrical Manufacturers Association (NEMA) in the United States also publishes protection ratings for enclosures similar to the IP rating system published by the International Electrotechnical Commission (IEC). NEMA however also dictates other product features not addressed by IP codes, such as corrosion resistance, gasket aging, and construction practices. For this reason while it is possible to map IP Codes to NEMA ratings that satisfy or exceed the IP Code criteria, it is not possible to map NEMA ratings to IP codes, as the IP Code does not mandate the additional requirements.

IP code	min. NEMA enclosure rating to satisfy IP code
IP20	1
IP54	3
IP65	4, 4X
IP67	6
IP68	6P