NFPA (Fire) 496

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Published:
04/23/2023
ANSI:
ANSI Approved
Number of Pages:
28
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NFPA (Fire) 496

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Codes and standards published by NFPA are displayed as read-only under license from NFPA solely for use within this system.  NFPA material may not be downloaded, printed, reproduced, or transferred.

Help mitigate risks by complying with the latest requirements for installing enclosures in Class I and Class II hazardous (classified) locations with NFPA 496.

Electrical equipment fires, explosions, and other dangers relating to the ignition of a flammable atmosphere pose a significant threat to life and property. Help identify and minimize potentially deadly hazards and better safeguard facilities by referencing and complying with NFPA 496, Standard for Purged and Pressurized Enclosures for Electrical Equipment.

This critical standard offers protection techniques applicable to Class I and Class II locations. You get comprehensive criteria for designing and operating purged and pressurized electrical equipment enclosures to minimize hazards in the presence of flammable materials.

This standard applies to purging and pressurizing for the following:

  • Electrical equipment located in areas classified as hazardous by Article 500 or Article 505 of NFPA 70®, National Electrical Code® (NEC®), 2020 edition. Electrical equipment containing sources of flammable vapors or gases that are located in either classified or unclassified areas
  • Control rooms or buildings located in areas classified as hazardous by Article 500 or Article 505 of NFPA 70
  • Analyzer rooms containing sources of flammable vapors or gases that are located in areas classified as hazardous by Article 500 or Article 505 of NFPA 70

The revised NFPA 496 is updated for consistency with the most current knowledge and NEC, 2020 edition, requirements.

It is vital electrical designers, installers, and AHJs have the most accurate and complete information for helping to ensure safety at Class I and Class II hazardous locations. This edition of the standard is updated to include significant changes in the Annex sections including:

  • Updates to Annex 4.3.1 to clarify components that complete the enclosure are subject to the same considerations as the enclosure itself
  • Details on methods to prevent the enclosure from excessive protective gas pressure added in A.4.3.1.1
  • Methods provided to prevent the discharge of ignition-capable particles to a Division 1 location in A.4.3.1.2
  • Included Annexes for 4.3.1 and its subsections to correlate with ANSI/ISA-12.04.04-2012, Pressurized Enclosures
  • Added requirements to 4.4.5 for alarms on pressurizing system bypasses and safety measures to prevent their accidental opening,
  • Introduction of French translations of required markings throughout the document
  • New guidance, including a possible test, to confirm that enclosures do not contain trapped flammable gases in A.5.2.3
  • Revisions to A.5.2.6 to indicate that internal components in or through enclosure walls might not be adequately protected by purge/pressurization
  • Addition of A.5.2.6.1 relating to internal components with a small internal volume that might not require protection

Help ensure you are up to speed on the methods for purging and pressurizing electrical equipment enclosures to prevent the ignition of a flammable atmosphere.

Be prepared to help protect people, equipment, and facilities by ordering your copy of NFPA 496, Standard for Purged and Pressurized Enclosures for Electrical Equipment, 2021 edition. (Print, 32 pp., 2021)

Product Details

Published:
04/04/2020
Number of Pages:
28

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NFPA (Fire) 496

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Protect electrical equipment in flammable atmospheres by following the protection techniques outlined in the 2008 NFPA 496.

NFPA 496: Purged and Pressurized Enclosures for Electrical Equipment contains requirements for the design and operation of purged and pressurized electrical equipment enclosures. This protection technique is used in Class I and Class II hazardous (classified) locations to reduce or prevent the presence of flammable materials within electrical equipment enclosures as specified by NFPA 70™: National Electrical Code®. NFPA 496 also includes chapters covering protection of analyzers and rooms housing analyzers as well as a chapter on pressurized control rooms.

Consistent with the 2008 NEC®, the 2008 NFPA 496 includes the following updates to help control fire hazards:

  • A new requirement to mark purged and pressurized enclosures with an asphyxiation hazard warning where the protective gas is other than air
  • Correlation with the NEC requirements on equipment temperature ratings

Product Details

Published:
03/14/2008
Number of Pages:
22

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NFPA (Fire) 496

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Protect electrical equipment in flammable atmospheres by following the latest protection techniques outlined in the 2013 NFPA 496.

NFPA 496: Standard for Purged and Pressurized Enclosures for Electrical Equipment contains requirements for the design and operation of purged and pressurized electrical equipment enclosures. This protection technique is used in Class I and Class II hazardous (classified) locations to reduce or prevent the presence of flammable materials within electrical equipment enclosures as specified by NFPA 70?: National Electrical Code?. NFPA 496 also includes chapters covering protection of analyzers and rooms housing analyzers as well as a chapter on pressurized control rooms.

Consistent with the 2011 NEC®, the 2013 NFPA 496 includes the following updates to help control fire hazards:

  • Revisions to the definitions for Type X Pressurizing, Type Y Pressurizing, and Type Z Pressurizing clarify that pressurizing keeps a flammable atmosphere around a protected enclosure from entering an enclosure, which enables the use of either ignition-capable equipment (in Type X Pressurizing or Type Z Pressurizing) or Division 2 or Zone 2 equipment (Type Y Pressurizing) inside an enclosure

    • .

  • Added a new requirement affecting electrical alarm actuators in Type Y Pressurizing to require them to be identified for a Division 1 or Zone 1 location
  • Clarified requirements affecting cutoff switch actuators in Type X Pressurizing

Order today to make sure you have the specialized knowledge needed to head off electrical equipment fires and explosions.

Product Details

Published:
12/17/2012
ISBN(s):
9781455905904
Number of Pages:
30

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NFPA (Fire) 496

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Install electrical equipment in Class I and Class II hazardous (classified) locations to prevent ignition of a flammable atmosphere. The 2017 edition of NFPA 496 helps you protect people, equipment, and facilities from potentially deadly hazards.

Work with the specialized knowledge you need to head off electrical equipment fires and explosions. Consistent with the 2017 edition of NFPA 70®: National Electrical Code® (NEC®), the 2017 edition of NFPA 496: Standard for Purged and Pressurized Enclosures for Electrical Equipment contains requirements for the design and operation of purged and pressurized electrical equipment enclosures.

This protection technique is used in Class I and Class II hazardous (classified) locations to reduce or prevent the presence of flammable materials within electrical equipment enclosures as specified by the NEC.

Electrical designers, installers, and AHJs reference NFPA 496 for vital requirements concerning:

  • General Requirements for Pressurized Enclosures
  • Pressurized Enclosures for Class I
  • Pressurized Enclosures for Class II
  • Pressurized Control Rooms
  • Pressurized Enclosures Having Internal Source of Flammable Gas or Vapor
  • Pressurized Analyzer Rooms Containing a Source of Flammable Gas, Vapor, or Liquid

To make the Standard more enforceable by states and jurisdictions, changes to the 2017 edition remove unenforceable language such as near, close to, and significant portion, because these terms cannot be quantified in the design or evaluation of an installation designed to NFPA 496 specifications.

Product Details

ISBN(s):
9781455914050
Number of Pages:
29

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