Where hazardous atmospheres can exist, electricity should be a primary concern of every engineer and system designer. Hazardous atmospheres can exist not only in the more common surroundings of industrial, chemical, and environmental facilities but also in many less obvious environs where dust is present, where gas can accumulate, and where combustible gas-forming reactions occur. To minimize risks in such areas, it is necessary to design speciŸc hazard-reducing electric systems. Most electric equipment is built to speciŸc standards aimed to reduce the incidence of Ÿres and human casualties. œe majority of such incidents can be attributed to poor or defective installations, improper use of approved equipment, deteriorated equipment, and accidental applications. In combination with an explosive atmosphere, these factors can result in extremely dangerous conditions. Designing an electric system for a hazardous location requires careful planning, research, engineering, and ingenuity in using proper protection techniques to develop better applications and classiŸcations that reduce hazards.