New area classification guidelines

In 1991, the American Petroleum Institute (API) merged their three area classification documents (RP500A for refineries, RP500B for production and drilling facilities, and RP500C for transportation/pipeline facilities) into one document, RP500. A common general section was supplemented with three other sections for specific recommendations for the three sectors of the industry, but, for all practical purposes, the RP was composed of the three previous recommended practices bound in a single cover. In 1997, API created RP505, Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class 1, Zone 0, Zone 1, and Zone 2, which will serve the petroleum industry essentially as an supplement to both ISA 12.24.01 (IEC 79-10 Mod) and National Electrical Code (NEC) Article 505. RP500, which underwent significant changes in 1997, is referenced by Article 500 of the NEC; it is proposed that the 1999 NEC will reference RP505. This paper provides a brief overview of the two new recommended practices, but primarily emphasizes the substantive changes and additions to RP500 and the portions of RP505 with the highest impact on the industry