Earthing systems worldwide and evolutions

Following an historical review of the origins of Earthing Systems, this "Cahier Technique" goes on to provide information on the practices in some countries concerning medium voltage, HV/LV substations, in particular in LV public, industrial and tertiary distribution. Electrical installations are evolving, electronics are everywhere, thus leading us to look afresh at earthing systems used in LV and indeed even to predict an evolution which should bring the TN-S and TT systems closer together. The criteria for the selection of earthing systems has changed. We advise those not very familiar with earthing systems standardised by IEC 364 to first read "Cahier Technique" no. 172.