How to classify electrically hazardous locations

摘要

Understanding the hazardous location requirements and how to protect against the potential hazards within them are important design considerations for all engineers. Without proper protection and consideration, electrical and electronic equipment and wiring can be left vulnerable to damage from fire or explosion hazards caused by hazardous gases, vapors, dusts or fibers. NFPA 70: National Electrical Code Articles 500 to 516 provide stringent requirements for electrical installations in locations classified as hazardous. However, it does not classify hazardous locations or their boundaries and therefore, must be used in conjunction with other NFPA standards. It is the responsibility of the authority having jurisdiction to provide the final say concerning the classi- fication of the area. However, the engineer is still required to provide quality design not only considering the classification of the area but also the equipment rating. The NEC provides two different classification systems for classifying hazardous locations: Classes and zones. This article will provide an overview on the class and division system, commonly practiced in the United States and will focus on the installation requirements in Class I hazardous areas.