ABSTRACT
Aesthetics is primarily the major reason for installing power cables underground, providing open views of the landscape free of poles and wires. One could also argue that underground lines are more reliable than overhead lines as they are not susceptible to weather and tree caused outages, common to overhead power lines. is is particularly true of temporary outages caused by wind, which represents approximately 80% of all outages occurring on overhead systems. However, underground lines are susceptible to being damaged by excavations (reason behind “call before digging” locating programs implemented by many states in the United States). e time required to repair a damaged underground line may be considerably longer than an overhead line. Underground lines are typically 10 times more expensive to install than overhead lines. e ampacity, current carrying capacity, of an underground line is less than an equivalent sized overhead line. Underground lines require a higher degree of planning than overhead, because it is costly to add or change facilities in an existing system. Underground cables do not have an inŸnite life, because the dielectric insulation is subjected to aging; therefore, systems should be designed with future replacement or repair as a consideration.
