Potentialausgleichspunkt

Potentialausgleich, often written Potenzialausgleich or referred to in English as equipotential bonding, is a safety principle in electrical installations that aims to prevent dangerous touch voltages by equalizing potential differences between conductive parts that a person could touch simultaneously. By connecting exposed conductive parts and extraneous conductive parts to each other and to the protective earth, potential differences that could arise during a fault or contact with live parts are minimized.

In practice, the system involves bonding diverse metallic components such as metal water and gas pipes, heating systems, structural steel, metal enclosures, and other conductive installations to the main earthing terminal. There are typically two levels: the main equipotential bonding that links these parts to the protective conductor, and, in some installations, supplementary bonding around particular areas or equipment where additional potential differences could occur. The goal is to maintain a common electrical potential across all connected parts so that a person touching multiple metal items is not exposed to a dangerous voltage.

Standards and jurisdictional rules govern the implementation of Potentialausgleich. It is addressed in many national and international standards for electrical installations, such as the IEC 60364 series and national adaptations (for example DIN VDE 0100 in Germany). Compliance requires careful assessment of building layouts, materials, and services to determine which parts must be bonded and how the bonding conductors are sized and connected. Potentialausgleich complements protective earthing by reducing touch voltages, but it does not replace proper insulation or fault-clearing protections.