Applies to rigid HV gas-insulated transmission lines (GIL) in which the insulation is obtained, at least partly, by a non corrosive insulating gas, other than air at atmospheric pressure, for alternating current of rated voltages of 72,5 kV and above, and for service frequencies up to and including 60 Hz.It is intended this technical report be used in situations where the provisions of IEC 60517 are not adequate.