This guide applies to three-phase overhead AC transmission line (110 - 1000 kV) design@ construction@ and it can be used as reference for lower voltage levels. This guide specifies design methodologies of the overhead transmission line conductors and ground wires@ insulators and fittings@ insulation coordination@ lightning protection and grounding@ conductor arrangement@ tower types@ tower loads and materials@ tower structure@ tower foundation. Purpose This guide applies to the design of AC overhead transmission lines@ and gives primary methods for electrical@ structural@ and foundation design. The design engineer can choose the appropriate design methods based on the location@ ambient conditions@ and importance of the line.