NFPA 496: Standard for Purged and Pressurized Enclosures for Electrical Equipment

Build your own set and Save 15%. NFPA Members save an additional 10%.

Item #: NFPA_496
Price: $0.00
Formats Available
Prior Years Prior Editions of NFPA 496


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. (Softbound, 21 pp., 2013)

NFPA® 496 Standard for Purged and Pressurized Enclosures for Electrical Equipment 2013 Edition

Chapter 1 Administration
1.1 Scope
1.2 Purpose
1.3 Application
1.4 Equivalency
1.5 Units of Measurement
1.6 Mandatory Rules, Permissive Rules, and Explanatory Material
Chapter 2 Referenced Publications
2.1 General
2.2 NFPA Publications
2.3 Other Publications
2.4 References for Extracts in Mandatory Sections
Chapter 3 Definitions
3.1 General
3.2 NFPA Official Definitions
3.3 General Definitions
3.4 NEC Extracted Definitions
Chapter 4 General Requirements for Pressurized Enclosures
4.1 Applicability
4.2 Suitability of Identified Equipment
4.3 Enclosure
4.4 Pressurizing System
4.5 Protective Gas System
4.6 Determination of Temperature Marking
4.7 Ventilated Equipment
4.8 Power Equipment
4.9 Type Z Pressurizing
4.10 Type Y Pressurizing
4.11 Type X Pressurizing
4.12 Markings
Chapter 5 Pressurized Enclosures for Class I
5.1 Applicability
5.2 General Requirements
5.3 Markings
5.4 Additional Requirements for Type Y or Type Z Pressurizing
5.5 Additional Requirements for Type X Pressurizing
Chapter 6 Pressurized Enclosures for Class II
6.1 Applicability
6.2 General Requirements
6.3 Markings
6.4 Marking Information
6.5 Additional Requirements for Type X Pressurizing
6.6 Additional Requirements for Ventilated Equipment
Chapter 7 Pressurized Control Rooms
7.1 Applicability
7.2 Protective Gas
7.3 Considerations Relating to Positive Pressure Ventilation
7.4 Requirements for Positive Pressure Air Systems
Chapter 8 Pressurized Enclosures Having an Internal Source of Flammable Gas or Vapor
8.1 Applicability
8.2 General Requirements
8.3 Specific Requirements
Chapter 9 Pressurized Analyzer Rooms Containing a Source of Flammable Gas, Vapor, or Liquid
9.1 Applicability
9.2 General
9.3 Specific Requirements
Annex A Explanatory Material
Annex B Informational References