What is equipotential bonding and what does it protect against?

• A. Grounding all digital electronics
• B. Bonding connections between exposed metalwork to maintain similar potential and avoid electric shock.
• C. Connecting all appliances to a common transformer
• D. Isolating all metalwork from the earth

Answer: (B)

Equipotential bonding means tying together exposed metal parts and certain other conductive parts so they all sit at about the same electrical potential. The goal is to create a low-impedance path to earth so that, if a fault makes a live conductor touch metal, that metalwork does not develop a dangerous voltage relative to earth or to other metal you might touch.

This keeps touch voltages very small, which reduces the chance of electric shock. It also helps protective devices (like fuses or circuit breakers and residual current devices) operate quickly by providing a clear fault path to earth, quickly removing the danger. In practice, it includes bonding exposed metalwork and extraneous conductive parts such as water and gas pipes to the earth/earthing system, ensuring all these parts stay at nearly the same potential.