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 Referenced By API RP 500 (R2002) - Recommended Practice for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Division I and Division 2 (Edition: 2nd) IEEE C2-2007 - National Electrical Safety Code (NESC), 2007 Edition NFPA (Fire) 70 - National Electrical Code, 2008 EditionProduct Replaces NFPA (Fire) 496 - Standard for Purged and Pressurized Enclosures for Electrical Equipment, 2003 Edition