In paper an approach to the choice of optimum cross-sections for high-voltage overhead lines by the modified method of economic intervals is proposed. The updated economic intervals' method has been developed that can use under market conditions. The method allows considering the discrete character of standard cross-sections’ scale, concrete technical and technically-economic parameters and technical limitations. For practical application of the modified method universal economic nomograms for overhead lines have been constructed and illustrated in paper for 20-110-330 kV lines with steel-aluminum wires.