A dielectric material that resists the flow of electric charge is called an insulator. In an electrical machine, the electrical insulation ensures that current flows only along the conductors and not between individual conductors or between the conductor and the ground. In electrical systems, insulators are commonly used as a flexible coating on electric wire and cable to avoid wires from touching each other and be touched, and preventing electrocution and fire hazards. Dielectric materials do not conduct electricity; they have a very low electrical conductivity. Power electrical equipment when in service is a source of thermal energy. Its conductors may be heated up to very high temperatures, particularly in systems with high currents flowing through the conductors. In the inland environment, the source of pollution is mostly soil dust, which is not very conductive and adhesive and usually can be easily removed by natural and artificial washing.