The grounding of power systems above 600 volts: a practical view point

This paper discusses grounding practices used on electric distribution systems above 600 volts. In particular, the paper concentrates on the three-phase four-wire, multi-grounded neutral system that is extensively used in North America. The paper addresses the benefits of the multi-grounded power system and makes comparisons with other grounding system designs including ungrounded; three-wire single-point grounded; three-phase, four-wire single point grounded neutral; and the three-phase, five-wire systems. Advantages and disadvantages of each system are discussed. Some criticism regarding stray currents and stray voltages has been made of the multi-grounded neutrals on electric distribution systems and this is discussed. Technical responses are made to these comments including a discussion on reasonable solutions, alternative designs, and "acceptable risks.".