Proposed revisions to IEC 60079-15 how has harmonization affected Ex nA motors?

Electric motors with the Ex nA designation have been operating in Zone 2 hazardous areas of the petrochemical industry for many decades. The majority of electric motors operating in Zone 2 hazardous areas use type of protection nA. There motors are also categorized as ldquononarcingrdquo/ldquonon-sparkingrdquo motors. The Zone 2 hazardous area, whether in North America or in any other part of the globe, is generally the same for the petro-chemical industry. However, the motors operating in this area are assessed differently. The present (3^rd) edition of IEC 60079-15 [4] used to evaluate Ex nA motors differs significantly from the North American standards applied in accordance with the in NEC [1] or CEC [2]. There were many issues in applying, operating, and maintaining of Ex nA motors in critical areas such as off-shore oil platform where Zone 1 and Zone 2 areas in very close vicinity, very corrosive atmosphere, wrong selection of enclosure, common lube oil system etc. In order to resolve these issues, the motor requirements of the 3^rd edition of IEC60079-15 are almost the same as those in IEC 60079-7[7] for Ex e motors intended for Zone 1 areas. The history of recordable incidences in UK from 1982 to 1992 is provided in the PCIC paper [11]. Two more incidences occurred since then, in the year of 2006 in Africa, and in the year of 2008 in Calgary-Canada. Both incidents were related to the common lube system where flammable gas leaked in to the motor enclosure. The 4^th edition of IEC 60079-15, now under development, is addressing many issues with the 3^rd edition. In our opinion, it will harmonize, in many ways, to the approaches used in North America. The authors would like to highlight the key proposed changes in this paper.