There are two major electrical manufacturing organizations monitoring product enclosures and/or their degree of protection; each organization also publishes technical manufacturing standards. The National Electrical Manufacturers Association (NEMA) Standard 250-2003 addresses non-hazardous locations, enclosure design and its environmental performance requirements. These are referred to as NEMA Types. (www.nema.org)
The International Electrotechnical Commission (IEC) 60529 Standard addresses Ingress Protection (IP); this describes the degree of protection provided, not the enclosure itself. The first digit of the IP Code designation describes the degree of protection against the ingress of solids; the second digit designates the degree of protection against the ingress of liquids. IP Codes support NEMA Type designations. (www.iec.ch)
The following information is taken from both electrical industry Standards; it matches NEMA Ratings with its IP counterpart, with a brief description of each rating.