In electrical engineering, hazardous locations (sometimes abbreviated to HazLoc, pronounced Haz·Lok) are defined as places where fire or explosion hazards may exist due to flammable gases, flammable liquid–produced vapors, combustible liquid–produced vapors, combustible dusts, or ignitible fibers/flyings present in the air in quantities sufficient to produce explosive or ignitible mixtures. Electrical equipment that must be installed in such classified locations should be specially designed and tested to ensure it does not initiate an explosion, due to arcing contacts or high surface temperature of equipment.