National Electrical Manufacturers Association Type 4X: Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (windblown dust); to provide a degree of protection with respect
Mandatory for Gulf of Mexico Class and Zone Rating. Most international markets require recognition under the International Electrotechnical Committee (IEC) Ex scheme
Electrical safety ratings in the US are governed under the National Electrical Code (NEC). There are two separate classification systems (NEC 500 and NEC 505). The NEC is approved as an American national standard by the American National Standards Institute (ANSI).