A luminaire or motor may emit a small spark or operate at an elevated temperature when powered by electricity. Under normal conditions, the potential risk of fire or electric shock would be a cause for concern. However, in hazardous locations, this spark or thermal affect may cause an explosion. When electrical or non-electrical equipment is used in potentially explosive conditions, the devices must be designed to mitigate the risks of igniting in order to help protect employees and property.

In 1894, William H. Merrill founded UL (Underwriters Laboratories) with a focus on electrical and fire safety. Soon after, UL leaders saw the need for safety certification of electrical products intended for locations where explosive gases and dusts were present, like a coal mine. To support this need for certified products, codes and standards were developed that reflected the evolving technology and associated risks.

In response to innovation, UL issued the first hazardous locations safety certification of an outlet box in 1915. This began what has become a 100-year effort of helping protect buildings and people from explosion hazards.

Today, UL continues its mission by providing manufacturers with global technical expertise and market access for the United States, Canada, Europe, and other international markets. To provide local support, UL has Hazloc engineering staff in 12 countries and in four continents, including Hazloc testing capabilities in the U.S., Europe and Asia.