Designed for use in Class II Division 1 and 2 locations as defined in Article 500 of the National Electrical Code. Class II locations, hazardous due to the presence of combustible dusts, are classified as follows: Group E—Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys in hazardous concentrations Group F—Atmospheres containing carbon black, charcoal, or coke dust in hazardous concentrations Group G—Atmospheres containing combustible dusts such as flour, starch, or grain dusts in hazardous concentrations Class II enclosures prevent ingress of combustible dust. NOTE: Hoffman NEMA Type 9 enclosures are not suitable for use in locations that are hazardous due to the presence of combustible liquids, vapors, or gases.