ABSTRACT
Underground distribution is much more hidden from view than overhead circuits, and is more reliable. One of the main applications of underground circuits is for underground residential distribution (URD), underground branches or loops supplying residential neighborhoods. A classic URD circuit is an underground circuit in a loop arrangement fed at each end from an overhead circuit. The main factors that influence underground costs are: degree of development; soil condition; urban, suburban, or rural; conduit; cable size and materials; and installation equipment. Political pressure coupled with technology improvements were the driving forces behind underground distribution. Whether urban, suburban, or even rural, all parts of a distribution circuit can be underground, including the main feeder. For reliability, utilities often configure an underground main feeder as a looped system with one or more tie points to other sources. Cables, connectors, and installation equipment have advanced considerably making underground distribution installations faster and less expensive.
