ZIPSE’S LAW AND ITS DANGERS IN GROUNDING ELECTRICAL SYSTEM

ZIPSE’S LAW
Donald Zipse in 2001 introduced to PCIC Zipse's Law which states: In order to have and maintain a safe electrical installation:

All continuous flowing current shall be contained within an insulated conductor or if a bare conductor, the conductor shall be installed on insulators, insulated from the earth, except at one place within the system and only one place can the neutral be connected to the earth.

This author takes great exception to that statement and believes it to be false and misleading. Zipse's Law is contrary to the National Electrical Safety Code [1] that not only allows, but also advocates the use of the multi-grounded neutral system.

Next, the National Electrical Code [2] not only allows the use of the multigrounded system, it specifies the maximum distance of 400 meters between grounds on the neutral.

The single-point, grounded system is seriously limited by any neutral current flow which will increase the voltage drop and cause neutral shifts for single phase and unbalanced, three-phase, four-wire loads.

In addition, the zero sequence impedances will be of such magnitude that full line-to-line rated surge arresters will be required. The use of the single point grounded system would essentially dictate the use of delta primary windings and line-to-line connected singlephase
transformers.

The three-phase, four-wire system would have to be totally replaced. The price of such a system would be cost prohibitive.

Another problem with the single point grounded system is that a break in the neutral could cause a neutral shift that may result in unacceptably high and low single-phase voltages.

This is similar to the reason that utility companies ground the neutral of secondary services and the NEC requires a grounding conductor on the neutral of a service entrance.

The grounding conductor will help maintain neutral stability.

In conclusion, Zipse's law is not only invalid, but it also presents potentially unsafe conditions for the utility workers and general public.

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