Hazardous locations are defined as areas where potentially explosive or combustible gases, dusts or fibers and flyings exist or may exits.  This definition is taken from the National Electric code, however the definition is just about the same any place in the world. What is different, is how hazardous locations are classified and the explosion protection methods and wiring methods that are used. The United States has traditionally used a system of Classes and Divisions.  The Classes identify the type of hazardous material and the Divisions define the normal or abnormal conditions of which the hazardous materials may be present. Class I Class II Class III Combustible Gases or Vapors Combustible Dusts Combustible Fibers                                                                                                                   Division 1 Division 2 Normal Conditions Abnormal Conditions The European Community and many other nations in the world use or have been influenced by the International Electrotechnical Commission (IEC) Zone concept.   This concept classifies areas by gas groups and zones.  Zones are very similar to Divisions but are based more the length of time the hazardous material may be present. Gas Groups I Gas Groups II Mining Combustible Gas or Vapors   Zone 0 Zone 1 Zone 2 Flammable Material Present Greater that 100 hours Flammable Material Present 10-100 hours Flammable Material Present Less than 10 hours