NFPA 499:2021

Chapter 1 Administration1.1 Scope. 1.2 Purpose.1.3 Application. 1.4 Relationship to NFPA Codes and Standards. Chapter 2 Referenced Publications2.1 General. 2.2 NFPA Publications.2.3 Other Publications.2.4 References for Extracts in Recommendations Sections. Chapter 3 Definitions 3.1 General.3.2 NFPA Official Definitions. 3.3 General Definitions. Chapter 4 Combustible Dusts 4.1 General.4.2 Combustible Dust Testing.4.3 Additional Potential Combustible Dust Hazards.4.4 Classification of Combustible Dusts. 4.5 Hybrid Mixtures.4.6 Electrostatic Discharges.4.7 Ignition Criteria. Chapter 5 National Electrical Code (NEC) Criteria 5.1 Classification of Class II Hazardous Locations and National Electrical Code (NEC) Criteria.5.2 Classification of Combustible Dusts. Chapter 6 Classification of Combustible Dust Locations 6.1 General. 6.2 Conditions Necessary for Ignition of Combustible Dust.6.3 Class II, Division 1 or Zone 20/Zone 21 Classified Locations.6.4 Combustible Dust, Class II, Division 2 or Zone 22, Classified Locations. 6.5 Unclassified Locations. 6.6 Procedure for Classifying Areas. 6.7 Housekeeping.6.8 Extent of Hazardous (Classified) Locations. 6.9 Discussion of Diagrams and Recommendations. 6.10 Classification Diagrams. Annex A Explanatory Material Annex B Informational References

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.