Single-conductor power cables are widely used in cable lines in Armenia and provide greater current conduction and reliability than triple-conductor cables. In this paper, the optimal distance between single-conductor power cables in a three-phase power system for a given arrangement (horizontal in the plane or triangular) and ambient (ground) temperature are determined. The results for single-conductor cable arrangements are presented in graphical form. © 1998 Elsevier Science S.A. All rights reserved.