Equipotential Bonding System

Equipotential Bonding System: A Short Overview What it is and why it matters An equipotential bonding system is a safety network used in electrical installations to connect all exposed and extraneous conductive parts to a common electrical potential. The goal is to minimize voltage differences between metal parts that a person could touch, especially during a fault. By keeping these parts at nearly the same potential, the risk of electric shock is greatly reduced. Two main concepts - Main equipotential bonding: Bonding extraneous conductive parts (like metal water pipes, gas pipes, heating systems, metal distribution boards) to the building’s main earthing point. This helps ensure that these parts do not float to a dangerous voltage relative to the electrical installation. - Supplementary bonding: Additional connections within rooms, notably in areas with moisture or metal fixtures (such as bathrooms or kitchens), to further reduce potential differences between exposed conductive parts. How it works If a fault causes a live conductor to energize a metal part, the bonding network provides a low-impedance path back to the earth. Because all bonded parts are connected to the same potential, the voltage difference between them remains very small. This not only protects people from shock but also helps protective devices (like residual current devices) operate more reliably by not having to respond to large, dangerous potential differences. Where you’ll typically see bonding - Metal water and gas pipes and other extraneous conductive parts - Metal enclosures and customer equipment that could become live - Exposed conductive parts in wet or damp areas (bathrooms, outdoors, basements) - Building metalwork such as heated radiators, metal stairways, and structural steel where applicable Key elements and considerations - Bonding conductors: Copper is commonly used, sized according to local electrical codes to handle fault currents. The conductors connect extraneous parts to a main bonding point. - Main bonding point: A central connection point, usually tied to the building’s earthing system, where extraneous parts are bonded together. - Supplementary bonding: Additional bonding conductors within rooms or zones to reduce potential differences between exposed parts. - Not the same as protective grounding: Bonding helps equalize potentials, while the protective earth conductor provides a path for fault current to trip protective devices when needed. Safety and compliance - Local codes and standards vary by country (for example, references exist in regulations like BS 7671 in the UK or the NEC in the US). Always follow your local standards. - Installation and testing should be performed by a qualified electrician. Incorrect bonding can create safety risks or interfere with protective devices. - Regular inspection is important to check for broken or corroded connections, loose clamps, or damaged pipes that could compromise the bonding network. A quick takeaway Equipotential bonding is a foundational safety measure in electrical installations that minimizes dangerous voltage differences by linking exposed and extraneous metal parts to a common electrical potential. It complements, rather than replaces, proper earthing and protective devices. If you’re planning or assessing bonding in a building, consult the local electrical code and a licensed professional to ensure a compliant and safe installation.