LARGE MOTORS TO IEC ZONE 2 AND NEC/CEC DIVISION 2 - ARE THEY THE SAME?

摘要

Electric motors have been successfully used in hazardous areas since the National Board of Fire Underwriters (NBFU) recognized the need for special means of protection in 1905. Successor to the NBFU, the National Fire Protection Association (NFPA) created regulations for Division 1 and Division 2 in the United States 1947 National Electric Code (NEC)[1]. Thus, for over 60 years, large fabricated frame motors have been manufactured that are compliant with the requirements of NFPA 70 (or NEC[1]) for Division 2 hazardous (classified) areas. In parallel, they also meet Canadian Electric Code (CEC) Part 1,C22.1 [2] mandates. For Division 2 motors, there has been no substantive difference between the current NEC[1] and CEC[2] editions and those of the past three decades. However, codes and standards are transcending national barriers in an attempt to synchronize without sacrificing safety requirements. A case in point is the adoption of Zone designations within both the NEC[1] and CEC[2] to varying degrees. Comparatively, the International Electrotechnical Commission (IEC) 60079 series of standards for Electrical apparatus for explosive gas atmospheres has changed drastically in recent years. The standard IEC60079-15[4] addresses the requirements of non-arcing/sparking motors manufactured to meet the safety requirements of areas classified under the IEC/CENELEC rules for Zone 2 areas. The petroleum and chemical facility environments for IEC Zone 2 and NEC/CEC Division 2 are not different, yet the safety requirements and how the motors are used in these areas is addressed from competing vantage points. These diverging regulations are discussed below.