Mining equipment is strong enough, and often is exposed to moist air and coal dust. In operating conditions, coal dust and moisture deposited on the surface of the insulating parts of mining equipment, Because of this, there are leakage currents, which under certain conditions develop into a short-circuit currents. In periodic heating and cooling of electrical mining may form dew, which also creates the conditions for occurrence of faults. As in a coal mine methane (CH4), and often weighed coal dust, which can ignite and explode from an electric arc or spark by opening contacts equipment, all mine has a special explosion-proof electrical equipment and intrinsically safe. tings. To prevent an explosion of methane and coal dust due to leakage current to earth through the insulation of electrical equipment used mine auto protective power outage with special leakage relay. These relays shall protect personnel against electric shock, damage to the insulation and the appearance of buildings Electrical dangerous to human stress.