Hazardous Location Enclosures

These are some of the National Electrical Manufacturers Association (NEMA) standard designations for hazardous locations:

• Class 1 Div 1 Group C - Certified to provide a degree of protection against atmospheres typically containing chemicals such as ethylene, diethyl ether, or cyclopropane all or some of the time under normal operating conditions.
• Class 1 Div 1 Group D - Certified to provide a degree of protection against atmospheres typically containing compounds such as propane, gasoline, hexane, butane, naphtha, acetone, toluene, or isoprene all or some of the time under normal operating conditions.
• Class 2 Div 1 Group E - Certified to provide a degree of protection against atmospheres typically containing metal dusts, such as magnesium, all or some of the time under normal operating conditions.
• Class 2 Div 1 Group F - Certified to provide a degree of protection against atmospheres typically containing carbonaceous dusts, such as carbon black, coal dust, coke dust, or charcoal, all or some of the time under normal operating conditions.
• Class 2 Div 1 Group G - Certified to provide a degree of protection against atmospheres typically containing non-conductive dusts, such as flour, starch, grain, wood or plastic, all or some of the time under normal operating conditions.

These descriptions are derived from directives from the EU designed to protect employees by defining levels of protection of areas that pose explosion risks due to elements in the immediate atmosphere:

• ATEX Directive 94-9-EC Zone 1 - Rated for use in an environment where exposure to an atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is likely to occur occasionally (between 10 and 1000 hours/year) in normal operation.
• ATEX Directive 94-9-EC Zone 2 - Rated for use in an environment where exposure to an atmosphere consisting of a mixture with air of dangerous substances in the form of gas, vapor or mist is likely to occur occasionally (less than 10 hours/year) in normal operation.
• ATEX Directive 94-9-EC Zone 21 - Rated for use in an environment where exposure to an atmosphere in the form of a cloud of combustible dust in the air is likely to occur occasionally (between 10 and 1000 hours/year) in normal operation.
• ATEX Directive 94-9-EC Zone 22 - Rated for use in an environment where exposure to an atmosphere in the form of a cloud of combustible dust in the air is not likely to occur in normal operation but, if it does occur, will only persist for a short period (less than 10 hours/year).

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FAQ

Is a NEMA 4x enclosure explosion proof?

An enclosure with a NEMA 4x rating is corrosion proof. Explosion proof enclosures must have a NEMA 7 or NEMA 8 rating.