One Company's Guideline for Hazardous Area Classification

Historically, hazardous area classification has been the responsibility of the plant electrical engineer. In actuality, however, many projects were being designed with minimum input from plant engineering. Most consulting firms would use an ultra-conservative approach with little input from process engineers and no consideration for potential cost savings. The existing national standards and guidelines are written to provide safety and flexibility of design and are difficult for the inexperienced engineer to interpret. Even for the experienced engineers, this flexibility often leads to different interpretations for similar situations. In 1993 a small group of electrical engineers recognized a need for standardization without compromising safety, and formed a technical committee to address this issue. This paper will present the result of the committee's work as a corporate engineering technical guideline that is currently being used by Eli Lilly and Company.