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NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas

2021 NFPA 499 Recommended Practice - Current Edition
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  • Description

    The 2024 edition of this publication is now available. To purchase, please call 1-800-344-3555 or email your purchase orders to orders@nfpa.org for processing.

    Help ensure you and your team have the most current knowledge on selecting and installing electrical systems and equipment for safe use in locations classified as hazardous with NFPA 499, 2021 edition.

    The presence of combustible dusts in industrial settings where electrical systems and equipment are used represents a significant ignition hazard. NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, provides guidance for selecting electrical systems for safe use in Class II hazardous (classified) locations in accordance with relevant codes and standards.

    This essential safety document delivers criteria for designating classified areas where combustible dusts are produced, processed, or handled. NFPA 499 is a must-have for:

    • Anyone responsible for hazardous area classification in industrial facilities
    • Facility operators, installers, and maintainers of electrical equipment used in areas where combustible dusts are present
    • Owners or operators of industrial facilities, insurance professionals, AHJs, and enforcing officials
    • Manufacturers of equipment for use in electrically classified process areas
    • Design engineers/consultants, loss prevention or safety engineers

    The 2021 edition is updated for consistency with NFPA 70®, National Electrical Code®, 2020 edition, and the latest accepted practices in the chemical process industries.

    This recommended practice offers detailed guidelines, classification diagrams, and dust group classifications on an extensive list of combustible dusts.

    Revisions to the 2021 edition include:

    • Updated definition of combustible flyings to combustible fibers/flyings; added definition for ignitible fibers/flyings; and clarification of the classification of combustible fibers/flyings [These changes help ensure that material posing a flash-fire or explosion hazard is evaluated as hazardous (classified) locations regardless of particle size]
    • Inclusion of classification for portable electronic products (PEPs) to correlate with UL 121203, Portable Electronic Products Suitable for Use in Class I and II, Division 2, Class I, Zone 2 and Class III, Division 1 and 2 Hazardous (Classified) Locations
    • Edited area electrical classifications throughout the document to correlate with the NEC® electrical classification

    Help safeguard lives and property in the industrial workplace by complying with NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas.

    Stay on top of safety by ordering your copy of the 2021 edition today.

  • Table of Contents (2021 Current Edition)

    NFPA® 499 Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas, 2021 Edition

    Chapter 1 Administration
    1.1 Scope.
    1.2 Purpose.
    1.3 Application.
    1.4 Relationship to NFPA Codes and Standards.
    Chapter 2 Referenced Publications
    2.1 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
  • 2017 Edition Description

    2017 Edition

    This Recommended Practice is a vital first step for the selection of electrical systems and equipment for safe use in Class II hazardous (classified) locations in accordance with the NEC®.

    Up-to-date with NFPA 70®, National Electrical Code®, the 2017 edition of NFPA 499, Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas presents criteria to determine ignitability hazards in chemical process areas where combustible dusts are produced, processed, or handled.

    Make sure you can properly select and install electrical systems and equipment for safe use in Class II hazardous (classified) locations.

    Filled with detailed guidelines and diagrams, NFPA 499 also provides extensive data on physical properties of selected combustible dusts, including specific Class II, Division, and dust group information.

    The 2017 edition of NFPA 499 is revised for:

    • Greater consistency between the figures and text regarding a transitional classified location around doorways
    • Alignment with the 2017 edition of the NEC -- including addition of the zone classification system

    It's an important tool for anyone who performs hazardous (classified) area classification.

    NFPA 499 is used by facility operators and installers and maintainers of industrial equipment using electrical power that is to be located in or near areas where combustible dusts are produced, used, or handled; equipment manufacturers providing equipment suitable for use in such electrically classified areas; design engineers/consultants; and loss prevention or safety engineers. Insurance professionals, enforcing officials, and owner/operators of industrial facilities also need to stay up-to-date with the latest edition. (Print, 40 pp., 2017)

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