An Analysis of the Five-Wire Distribution System

Most power distribution systems in North America employ a four-wire multigrounded neutral design. A five-wire distribution design has been proposed and studied in a project cosponsored by EPRI, Empire State Electric Energy Research Corporation, New York State Electric and Gas Corporation, and New York State Energy Research and Development Authority. While summary information on the project claims that five-wire distribution is a viable means of dealing with stray voltage, magnetic fields, and high impedance faults, it does not appear that a balanced assessment has been presented. The purpose of this paper is to summarize the significant differences between the five-wire distribution system and the conventional four-wire multigrounded neutral system. Both four-wire and five-wire distribution are assumed to be multigrounded systems.