Progress of International Standardization
IEC Technical Committee 31 (IEC/TC31), Electrical Apparatus for use in Explosive Atmospheres, is the parent committee for several subcommittees, each responsible for a particular IEC standard covering a specific explosion-protection technique. The IEC/TC31 Committee prepares and maintains the IEC 60079 series, Electrical Apparatus for Explosive Gas Atmospheres; IEC 61241 series, Electrical Apparatus for Use in the Presence of Combustible Dust; IEC 61779 series, Electrical Apparatus for the Detection and Measurement of Flammable Gases; and IEC 62086 series, Electrical Resistance Heat Tracing Series of International Standards Covering Electrical Apparatus for Explosive Gas/Dust Atmospheres.
Basic to the design requirements is the zone system, separating the hazardous areas into Zone 0, 1 and 2, for gas atmospheres and Zone 20, 21 and 22 for combustible dust atmospheres. The safe use of the apparatus is ensured under the condition that the user has defined zone areas according to IEC 60079-10, Classification of Hazardous Areas, and has installed the apparatus according to IEC 60079-14, Electrical Installations in Hazardous Areas.
A safety level comparison between the Division system (the primary system traditionally used in North America) and this Zone system is feasible and is under consideration by more and more countries as part of their national installation codes. Canada and the United States have integrated both the Zone and Division system requirements into their installation codes, specifically, the Canadian Electrical Code (CEC) for Canada and the National Electrical Code (NEC) for the United States.
At present, the motivation to work out international harmonized standards is stimulated by ongoing market integration and industry mergers. In recognition of this, and in recognition of the efforts by IEC/TC31, a decision has been made by the CENELEC/TC31 committee to stop their activities in creating European Ex standards. Future European Ex standards development activities will now concentrate on internationally harmonized standards within IEC/TC31, especially to achieve worldwide acceptance. Such truly worldwide acceptance also requires the very important input of North American industry at the IEC/TC31 level.