Probability Factors as a Guide for Area Classification and Selection of Electrical Equipment

With regard to the classification of hazardous areas and the selection of appropriate electric equipment, there are discrepancies between the electrical codes of various countries and their interpretation. Work on intemational standardization of constructional requirements of apparatus is proceeding. However, there is no common opinion as to what type of equipment protection should be applied under specific circumstances. This is due to the fact that these circumstances are merely qualitative concepts. An attempt is made to base the selection on a quantitative approach by using a mathematical model supported by the probability theory.