NFPA 499

Abstract

This recommended practice provides information on the classification of combustible dusts and of hazardous (classified) locations for electrical installations in chemical process areas and other areas where combustible dusts are produced or handled. <br>This recommended practice provides information on combustible dusts as it relates to the proper selection of electrical equipment in hazardous (classified) locations in accordance with NFPA 70, National Electrical Code. <br>The tables of selected combustible dusts contained in this document are not intended to be all-inclusive. <br><strong>Purpose.</strong> <br>The purpose of this recommended practice is to provide the user with a basic understanding of the parameters that determine the degree and the extent of the hazardous (classified) location. This recommended practice also provides the user with examples of the applications of these parameters. <br>This recommended practice is intended as a guide and should be applied with sound engineering judgment. Where all factors are properly evaluated, a consistent area classification scheme can be developed. <br>This recommended practice is based on the criteria established by Articles 500 and 502 of <em>NFPA 70, National Electrical Code.</em> <br>The application of this recommended practice does not address all potential hazards associated with solid particulate materials, including, but not limited to, the possible need for explosion venting or explosion suppression addressed in other NFPA standards. <br>This recommended practice does not address the criteria for classifying locations in accordance with Article 506 of <em>NFPA 70, National Electrical Code</em>