What is equipotential bonding and which services are typically bonded?

• A. Connecting live conductors to each other
• B. Connecting exposed and extraneous conductive parts to protective earth to maintain equal potential
• C. Bonding only to the neutral conductor
• D. Bonding only electronic equipment leads

Answer: (B)

Equipotential bonding is about making all metal parts that could become energised reach the same electrical potential. By linking exposed conductive parts (the accessible metal of equipment, enclosures, taps, radiators, etc.) and extraneous conductive parts (metal services not normally part of the electrical circuit but that could become energised, such as water and gas pipes, metal heating pipework, and other metal building services) to the protective earth, any fault current preferentially travels to earth and the voltage difference between touched parts is kept very small. This dramatically reduces the risk of electric shock if a fault occurs.

In practice, the services that are typically bonded include the main water supply pipe and the gas supply pipe, as well as related metalwork like heating system pipes and metal building structures. These bonds help maintain a safe, low-potential environment around floors and fixtures where people might touch multiple metal surfaces at once.