|By Nailen, Richard L|
A look at the international standards governing apparatus for hazardous areas
"EX"- SHORT FOR "EXPLOSION" OR "EXPLOsive." Throughout most of the world, it refers to either an atmosphere containing a flammable gas, vapor, or dust, or to construction of equipment (primarily electrical, such as motors and control) that must operate safely within such an environment. "IEC," of course, refers to the
After several years of discussion, an IECEx Management Committee held its first meeting in 1 996. Three years later Publication 01, the Basic Rules of the system, was published. Other major developments in hazardous area equipment safety are shown in the time line of Figure 1.
The IECEx System has grown rapidly. At least 30 countries have now joined the program. Among those outside
Although the IEC standards system now involves nearly 100 nations, some national differences with local standards are unavoidable. For example, electrical system voltages, some circuit breaker ratings, and conductor sizes aren't interchangeable between the U.S. and many other countries. Some U.S. organizations, including UL, have made "national adoptions" of some IEC standards only by incorporating variations. Hence, the U.S. has become an IECEx member only with the proviso that full inclusion in the system will come only after resolution of national differences that may take 10-15 years.
How IEC and U.S. standards differ
One such difference is in the nature of the National Electrical Code, which is legally enforceable throughout much of the country. Code enforcement is not within U.S. government control. The NEC retains the Division system of classifying hazardous areas (more about this later) as well as protection against fire and electrical shock - conditions not dealt with in IECEx.
An essential feature of the IECEx program is acceptance by any member country of product evaluation or facility assessment by recognized authorities in other member countries. Full U.S. participation in IECEx suffered a setback when in
Scheme tends to imply something shady, underhanded, perhaps even illegal. In electrical technology, however, the word simply denotes a plan - a way of doing something. For example, a control scheme is an arrangement of circuits and devices to carry out a desired sequence of operations. The IECEx "Scheme" is more properly termed the IECEx "System," consisting of these four components:
1. Certified Equipment Scheme
2. Certified Service Facilities Scheme
3. Scheme for Certification of Personnel Competencies