Electrical equipment in hazardous areas the participation of operations, maintenance, safety, electrical and instrumentation professionals, the use of process diagrams and material flows, MSDS and any pertinent documents, information and knowledge to determine the hazards and their extent and the countermeasures to be employed. Area classification documentations are reviewed and updated to reflect process changes. Soon after the introduction of electric power into coal mines, it was discovered that lethal explosions could be initiated by electrical equipment such as lighting, signals, or motors. The hazard of fire damp or methane accumulation in mines was well known by the time electricity was introduced, along with the
Mines in the Battle of Messines (1917) on 7 June 1917, the mines at Messines were fired within the space of 20 seconds. The joint explosion ranks among the largest non-nuclear explosions of all time and surpassed the mines on the first day of the Somme fired 11 months before. The sound of the blast was considered the loudest man-made noise in history. Reports suggested that the sound was heard in London and Dublin, and at Lille University's geology department, the shock wave was mistaken for an earthquake. Some eyewitnesses described the scene as "pillars of fire", although many also conceded that the scene was indescribable. The