The Quest for Global Safety

The authors present a systematic study on the factors that have influence on the establishment of the safety conditions ensuring the rise of Global Earthing Systems. Starting from the definition of Global Earthing System given by CENELEC Document HD 637 SI and from the results of the studies done on the last years on the interconnected earthing systems inside MV networks, the paper proposes some directions of deepening on the topic of Global Safety. Some of the themes whom the paper deals with are: the correct definition of proximity, interconnection and quasi-equipotentiality of the earth electrodes belonging to a Global Earthing System; the influence of the presence of HV/MV stations on hazardous voltages and on the permissible voltage limits; the variability of the hazardous conditions for persons with the different kinds of fault that can occur inside the interconnected system; the effect on safety of the interconnection of HV, MV and LV earthing systems. The proposed study has the aim of throwing light on some aspects of an argument on which nowadays exist many heterogeneous studies but not still a normative clarity.