Hazardous Locations Certification
Hazardous locations are defined as premises, buildings or parts thereof where fire or explosion hazards may exist due to the presence of flammable gases or vapors, flammable liquids, combustible dusts or easily ignitable fibers or flyings.
Although flammable gases, vapors and combustible dusts exist almost everywhere, fortunately they are present only in minute quantities. Simply because flammable gases or vapors or combustible dusts are present, there is not necessarily a hazardous location. The quantities or concentrations must be sufficient to present a potential explosion hazard.
The evolution of hazardous location electrical codes and standards throughout the world has taken two distinct paths.In North America, a “Class, Division” System has been used for decades as the basis for area classification of hazardous (classified) locations. Because the hazards and methods of protecting electrical equipment against these hazards differ for different materials, hazardous locations are divided into three Classes and two Divisions. The Classes are based on the type of hazard and the explosive characteristics of the material, while the Divisions are based on the occurrence or risk of fire or explosion that the material presents. While the United States and Canada have some differences in acceptable wiring methods and product standards, their systems are very similar.
In other parts of the world, areas containing potentially explosive atmospheres are dealt with using a “Zone System." Zones are based predominantly on the International Electrotechnical Commission (IEC) and European Committee for Electrotechnical Standardization (ATEX / CENELEC) standards. Whereas North America deals with multiple types of hazardous atmospheres, the North American Zone System presently addresses only flammable gases and vapors, which is the equivalent to North America’s Class I locations. The most significant difference in the Zone system is that the level of hazard probability is divided into three Zones as opposed to two Divisions.