Abstract A method of calculating non-equipotential closed earth-return circuits, each of which contains n points of current energization and current outflow, is presented in the paper. A mathematical model and an algorithm for its solution are included. In this method the electrical properties of conductors are described by means of unit-length and wave parameters. Numerical calculations of potentials along railway rails are made on the basis of the presented algorithm. Conclusions are formulated from an analysis of the method.