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Electrical installations in hazardous locations (classified areas) need careful attention because non-conformities can bring considerable risks not only to the site, but also for other industries and residential areas nearby. To assure safe operation of an industrial facility it is necessary not only that all electrical and electronic equipment to be used in hazardous locations is correctly specified and purchased (known as “Ex equipment”), but also properly installed and maintained. The discussion in this paper is largely based upon International Electrotechnical Commission (IEC) standards; however, conceptually the same philosophy applies to American based standards and installations as well.

This paper evaluates the protection system of an offshore gas production unit and proposes utilization of devices dedicated to identify the arc flash incidents inside the panels. A quantitative analysis has been performed by comparing the incident energy levels of the original design with the levels provided by the new design. The new design includes numerical relays equipped with dual sensing of arc flash: optical detection of the light and high-speed overcurrent detection. The analysis indicates that a drastic reduction of incident energy can be achieved. The reduction is based on very fast detection and elimination of the arc, lowering the arcing time.