The article briefly describes the technical solution for the use of specialized fiber-optic cable embedded in ground wire (OPGW) on the sections of electric Railways AC. The technical solution is to combine in a single conductor functions return conductor and fiber optic communication lines. Are given the relevance of such decisions and some peculiarities of its implementation. The main part of the article examines to the selection options return conductor with combined functions. The article describes the theoretical dependencies for the combined selection of the conductor based on the thermal resistance criterion. As one of the main passport parameters of the OPGW cables is the section of the metal component, the percentage of their content and the variation percentages are used in calculations to determine the electrical resistance of the cable and the magnitude of the permissible current. This approach allows to determine the parameters of the cable based on the criterion of reliability and allows to obtain the cable composition for a subsequent order from the manufacturer. The algorithm of selection combined return conductor that contains two stages: pre-selection based on the reference data, the choice of the real parameters from the manufacturer.

Keywords: OPGW, reverse wire, combined reverse wire, electrothermal degradation, fiber-optic transmission lines railway transport, traction network, the choice of combined shield wire