Of international terminology and wiring methods used in the matter of bonding and earthing of low-voltage power systems

The worldwide global market requires electrical engineers to have a deep understanding of the bonding and earthing practices adopted in different countries around the world. This knowledge is essential to obtain effective design and high safety standards, and can promote the elimination of technical obstacles that can still create market barriers. The full comprehension of the "grounding" theory requires the command of key technical concepts regarding the earthing methods, which may be cause confusion when used in the North American technical realm rather than in the IEC world. This issue is further worsened by the lack of literature in this matter, as well as of harmonization documents between national codes and international standards. This paper, by analyzing the protection against indirect contact in a.c (50/60 Hz) low-voltage power systems by automatic disconnection of supply, seeks to clarify both the terminology and each type of grounding system adopted in IEC standards, with the intent to create a common reference for practicing engineers in the matter of bonding and earthing of power systems. Major differences encountered between sizing procedures adopted in IEC standards and the North American National Electrical Code are also examined.