Revision Standard - Inactive - Superseded.Superseded by IEEE Std 367-1996. Guidance is provided for the calculation of interfering voltages and their appropriate reduction from worst-case values for use in wire-line telecommunication protection design. Information is also included for the determination of the fault current and earth-return current levels; their probability, waveform, and duration; and the impedance to remote earthing points used in these ground potential rise (GPR) and longitudinally induced voltage calculations. The zone of influence of the power station GPR; the calculation of the inducing currents; the mutual impedance between power and wire-line telecommunication facilities and shield factors; and the channel time requirements for wire-line telecommunication facilities where noninterruptible channels are required for protective relaying and other purposes are covered.