
dusttight enclosures as NEMA Types 3, 4, 4X, 12, 12K, and 13. NEMA 12, 13 and 13K are
indoor enclosures.
Hermetically Sealed
Hermetically sealed protection techniques prevent the entrance of atmospheric combustible
materials by the use of fusion techniques on electrical components in an enclosure. Soldering,
brazing, welding, and glass fused to metal are techniques that will prevent the entry of
combustible materials.
Hazardous (Classified) Area Equipment Standards
Selected standards applicable for electrical equipment utilized in hazardous (classified)
locations are presented in Table 9.16. This table represents some of the most commonly
referenced standards. ...