Power transmission lines are generally divided into two types: overhead lines and cables. Overhead lines are composed of copper or aluminum wires along with steel wires to support their weight, forming a steel core aluminum stranded wire. Since the insulation safety distance from the ground for 110kV lines is usually above 10 meters and for 220kV and 330kV lines it is even higher, the lines must be overhead to ensure insulation. Cables, on the other hand, are covered with insulating materials and can be touched by hands, so they are placed underground.