EN 60529 is a European directive designed to specify degrees of protection provided by electronic enclosures.
EN 60529 is governed by CENELEC – The European Committee for Electrotechnical Standardization. It is a standardized measure to ensure that computer enclosures can cope with certain criteria.
The directive gives a two digit IP rating (ingress protection) for each enclosure, these two digits represent the different types of protection. The first digit represents solid matter whilst the second digit represents liquid protection. As an example an IP 65 enclosure offers better dust protection but less water protection than an IP 54 unit.
The usefulness of the EN 60529 directive is testified by the number of businesses outside the EU that are starting to use the directive, despite their being an alternative.
The USA’s NEMA (National Electrical Manufacturers Association) has a similar rating system to the EU directive although NEMA rates ingress protection with a single number. Although NEMA has an alternative number to each IP rating, being only a single digit number there is less scope in the American system.
While it is possible to convert the NEMA rating system to the European rating it is not quite possible to do the conversion the other way around as there is less scope in the NEMA system (although the testing is argued to be more stringent).