What is the role of the main bonding conductor in electrical installations?

• A. To carry all operational current around the premises
• B. To connect neutral and earth at the main panel
• C. To ensure a low-resistance path to earth for safety in faults
• D. To protect sensitive equipment from surges

Answer: (C)

The main bonding conductor provides a low-impedance path to earth so fault currents can return quickly to the source. By bonding exposed metalwork and important metallic services to the earth, it keeps all those surfaces at the same potential. If a live conductor touches any of them, a large fault current flows through this bond to earth, which causes the protective device (fuse or breaker) to trip rapidly and disconnect the supply. This minimizes the risk of electric shock and fire.

It's not intended to carry normal operating current, and while a neutral-to-earth link exists in some systems at the main service, that is a separate arrangement from the bonding conductor’s primary safety role. It also doesn’t specifically protect against surges; that function is handled by dedicated surge protection devices.