Practical considerations of area classification: More is not better

Article 500 of the National Electrical Code (NEC) defines the specific electrical equipment and installation methods that are to be utilized in Class 1 area classifications. Once the area´s classification has been determined as either unclassified, division 2, or division 1 (in increasing order of severity), the electrical equipment and installation methods are limited to those described in the NEC. There is a substantial increase in the electrical equipment purchase, installation, and facility operating costs when moving from an unclassified to a division 2 location. A similar, often greater, cost increase occurs when moving from a division 2 to a division 1 location. When there is uncertainty about whether an area is unclassified, division 2, or division 1 there is a tendency to increase the classification (choose the more severe interpretation). This more severe choice is made in the belief that it achieves an increased level of safety, which in turn justifies the cost increase. The validity of that belief is examined to provide insights to help make better area classification decisions by eliminating some of the uncertainty