Main protective bonding

Conductors connecting incoming metallic services — water, gas, oil, structural steel — to the main terminal. Bonding does not clear faults; it holds the touchable metalwork of a building at roughly the same potential while a fault lasts, so a person touching a pipe and an appliance at the same moment isn't bridging a dangerous voltage difference.

Where to look it up: BS 7671 Chapter 41.

Taught and practised in the Installation section.