Abstract An analytical method is presented which can be used to estimate grounding effects of the shield wires, voltage transfer and distribution of ground fault currents. In the case of lines which can, as regards earthing, be treated as infinite, the method is based on relatively simple equivalent circuits obtained by applying the expression for the earthing impedance of an infinite line and summation of finite geometric series. In the case of lines which cannot be treated as infinite, use is also made of the principle of superposition and the summation of infinite geometric series. Some numerical examples are given to illustrate the practical application of the method. Finally, the method is used to derive an analytical proof of the specific property of shield wires as earthing conductors that they partially compensate for the unfavorable influence of high soil resistivity on the resistance of the earthing electrodes which they connect.