Identification of Global Grounding Systems: The Global Zone of Influence

The International Electrotechnical Commission Standard 61936-1 “Power installations exceeding 1 kV a.c.” defines the “global grounding system” (GGS) as an equivalent grounding system that ensures “no dangerous touch voltages.” This paper deals with an analysis of the parameters that characterize the behavior of grounding systems (GSs) operating in the same zone of influence (ZOI) and proposes to recognize four levels of “globality.” With this aim, the geometric criterion and the safety criterion are introduced to identify the ZOI. The safety criterion allows for identifying a GGS and characterizing the global ZOI of a GGS. This paper highlights the relevance of recognizing what is intrinsically safe for a GS that guarantees safe touch/step voltages lower than permissible permanent voltages. An integration of many coexisting GSs for constitution and extension, naturally, can reach the level of an intrinsically safe GS and, hence, of a GGS.