Magnetic Field Management Considerations for Underground Cable Duct Bank

Interests in magnetic fields over the last 15 years have been a transient issue, but general utility guidelines are to practice prudent avoidance where possible. This paper discusses various design issues considered by a utility preparing to underground an existing overhead transmission line in an area that has seen significant residential growth and general encroachment near and onto the overhead line's right-of-way. The utility's consultants evaluated various cable and magnetic shielding configurations to minimize the resulting magnetic fields from an underground cable system along the duct bank and near manholes