Transmission line phase conductors and overhead wires are affected by sag that vary the distance of
these conductors to the earth. This corresponds to a varying separation distance of current carrying
phase conductors producing the magnetic fields to parallel pipelines in shared corridors. This paper
explores the effects of phase conductors and shield wires’ sag to evaluate the induced voltages on
parallel pipelines. Methodologies to consider the sag of the conductors include catenary curves, straight
sloped conductors mimicking the maximum and minimum conductor elevations, and uniform conductor
elevations. A sampling of typical voltage levels, spans, and transmission line phasing configurations are
evaluated utilizing commercial software.

The paper provides an explanation of the impacts of sag and provides a reference for considering the
inclusion of catenary curve compared to simpler approximations of the conductors for a transmission line.
Identification of transmission line configurations that increase the significance of the induced voltages on
parallel pipelines helps to improve public and personnel safety in shared corridors.