The characteristic feature of bare overhead cables, distinguishing them among other energy carriers, is the use of air as a natural insulation for cables hanging in line. The specially designed insulators are installed only in places with the suspension of cables on pillars. The reduced need to use additional insulating materials and relatively simple and low cost structure, in conjunction with well-mastered installation techniques, make up the relatively low costs of the construction of an overhead electrical network. For this reason, bare cables are the preferred means of energy transport, particularly in the case of high and medium voltage power lines.
Today the most commonly used conventional bare cables can be divided into three main types, which differ from each other in the main materials used to produce them.