NFPA 499 Revision Update

On January 18, 2016, the National Fire Protection Association (NFPA) published the 2nd draft report for NFPA 499: Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations in Chemical Process Areas. It is now open for a Notice of Intent to Make a Motion (NITMAM) until February 19, 2016 for those on a Committee Comment, Second Revision, or Second Correlating Revision. The purpose of NFPA 499 is to provide information on classifying combustible dusts and locations and provide recommended practices on proper selection of electrical equipment in hazardous (classified) locations per NFPA 70, National Electrical Code. NFPA 499 is a compendium document to Chapter 5 (Article 500) of NFPA 70 and does not supersede any requirements of other NFPA standards (e.g. NFPA 61, 68, 69, 654, 664, etc.).

The significant changes for the 2016 revision includes classifications and definitions for the following:

  • Class III fibers/flyings;
  • Area Classification Zones (Zones 20, 21, and 22) based on the International Electrotechnical Commission (IEC) Zones;
  • Class/Division Group E, F, and G dusts;
  • Zone Group IIIC, IIIB, and IIIA dusts.

The previous editions of NFPA 499 did not provide definitions of Class III fibers/flyings or Group E, F, G, IIIA, IIIB, and IIIC dusts; however, these definitions were already established in NFPA 70. The more significant change is the inclusion of the Area Classification Zones 20, 21, and 22. With this inclusion, NFPA 499 now provides the criteria for classifying locations in accordance with Article 506. Several comments have been made by the Committee that the inclusion of the Zone area classifications conflicts with ANSI/UL 60079-10-2 in that the Zone area classifications proposed may not align specifically to the IEC definitions. If true, this could prevent ANSI adoption of the standard.

Notably absent from this draft is any reference to NFPA 652: Standard on the Fundamentals of Combustible Dust. The first draft of NFPA 499 was posted in early 2015 based on public comments submitted in 2014, prior to publication of NFPA 652. Additionally, NFPA 499 is not a reference document in NFPA 652; however, NFPA 499 is an important tool in conducting the Dust Hazard Analysis (DHA) required by NFPA 652 as it provides guidance on how to classify hazardous locations such that the electrical requirements per NFPA 70 can be evaluated. This includes diagrams providing examples of various common combustible dust operations/sources and guidance on the extent of area classifications.

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