Practical considerations of area classification: how for to classify

Defining the classification of a location or facility (class, group, and division), while often a difficult and time-consuming task, is only the first of three separate and distinct tasks that must be performed by those who provide electrical area classification. This first task defines the kinds of materials that are present in the location using the terms class, group, and division. The second task is to choose electrical equipment and installation techniques appropriate to the class, group, and division decisions assigned to the location in the first task. The third and final task in electrical area classification is to determine the physical boundaries or extent of the areas that are influenced by the class, group, and division decisions reached in the first task. The NEC and RP 500 are both used in this final task of electrical area classification. This article concentrates on the methods used in the third task to determine the physical boundaries or extent of classified areas. The author concentrates on the third task, with the intent of providing the skills and insights that are necessary to properly determine the physical boundaries of classified areas consistent with personnel and facility safety. Only Class I, Division 2 locations are examined.