What is the role of protective bonding across exposed metal services in a building?

• A. To ensure all exposed metalwork is at the same potential, reducing touch voltage and aiding fault clearance
• B. To increase the impedance of fault paths
• C. To isolate metal parts from earth for safety
• D. To provide decorative finish

Answer: (A)

Protective bonding across exposed metal services creates an equipotential network so all exposed conductive parts are at the same electrical potential. By tying together metalwork such as pipes, structural steel, cables, and other exposed surfaces, a fault current has a low-impedance path back to the supply, keeping touch voltages small if insulation fails and allowing the protective devices to trip quickly to clear the fault. This is not about increasing impedance, isolating metal from earth, or adding decoration—the aim is to ensure safety by preventing dangerous voltage differences between metal parts that a person could touch.