Two separate pathways have been followed in the global growth of electrical rules and standards for hazardous locations.
For decades, a "Class, Division" System has served as the foundation for the area categorization of hazardous (classified) places in North America.
Considering the risks and defence strategies
various materials require various electrical equipment to protect against these risks, and hazardous areas are broken down into three classes and two divisions.
Areas with potentially explosive atmospheres are handled utilising a "Zone System" in various regions of the world. The International Electrotechnical Commission (IEC) and the European Committee for Electrotechnical Standardisation (CENELEC) are the main standards on which zones are based.
The "Class, Division" System and the "Zone" System are contrasted in the table below.
The amount of danger in a site is determined by the frequency of occurrence; the longer a substance is there, the greater the risk.
The variances between the several Zones are depicted in the following chart.
In terms of risk assessment, the figure below contrasts the Division and Zone systems.
