For many years, the mystery of area classification has resided with a select group of experts within the electrical, petrochemical and industrial sectors. Many electricians, electrical engineers, fire inspectors and electrical inspectors have remained outside of this group. Instead, designers and installers rely on National Electrical Code (NEC) articles 500 through 517 for installation requirements regarding hazardous (classified) locations. Rightfully so, but often, these industry personnel do not understand the original basis for these requirements.