What is the minimum size of the main bonding conductor acceptable in a domestic installation?

What is the minimum size of the main bonding conductor acceptable in a domestic installation?

• A. 4 mm2
• B. 6 mm2
• C. 10 mm2
• D. 8 mm2

Answer: (C)

Bonding extraneous conductive parts to earth in a domestic install must be large enough to carry the fault current quickly so the protective device can trip in time. If the bonding conductor is too small, its impedance is too high, and the fault current may not be enough to trip the breaker promptly, leaving exposed parts at dangerous voltages. The standard minimum for the main bonding conductor is 10 mm2 copper, which provides a low enough impedance to ensure rapid disconnection under fault conditions. Smaller sizes would not guarantee timely tripping, while larger sizes are acceptable but not required.

Bonding extraneous conductive parts to earth in a domestic install must be large enough to carry the fault current quickly so the protective device can trip in time. If the bonding conductor is too small, its impedance is too high, and the fault current may not be enough to trip the breaker promptly, leaving exposed parts at dangerous voltages.

The standard minimum for the main bonding conductor is 10 mm2 copper, which provides a low enough impedance to ensure rapid disconnection under fault conditions. Smaller sizes would not guarantee timely tripping, while larger sizes are acceptable but not required.