IECEX certification schemes versus ATEX directives

Today, two international certification schemes exist for hazardous area. One scheme is endorsed in Europe under the ATEX Directives the other scheme is the IECEx system which provides a more international but voluntary equipment certification scheme accompanied with the conformity mark license scheme and other certification schemes for service facilities and persons. This paper targets at audience from plant operators, engineering contractors, installers and equipment manufacturers involved with hazardous area equipment. The paper outlines the similarities and differences between the two schemes in order to help answering questions like: 1. Which certification requirements are applicable to equipment on plants? 2. What is the most convenient way to certify assemblies? 3. What about equipment with certificates of component? 4. What are the benefits of the voluntary IECEx certification scheme? 5. Which scheme is the best choice in which situation?