What is bonding and why is it necessary?

• A. Bonding increases the overall system voltage and is primarily used to boost performance.
• B. Bonding creates a path to ensure metallic parts are at the same electrical potential, reducing shock risk.
• C. Bonding is the same as grounding and can replace the grounding conductor.
• D. Bonding only applies to disconnect switches and not to enclosures.

Answer: (B)

Bonding is about linking all exposed metal parts so they share the same electrical potential. By creating a continuous, low-impedance path between metal enclosures, conduits, equipment, and other conductive parts, bonding prevents dangerous voltage differences from appearing on surfaces that someone might touch. If a fault occurs where a live conductor contacts a metal part, the fault current has a clear path back to the source through the bonding network, causing protective devices to trip quickly and reducing the risk of electric shock or severe arcing.

It’s not about increasing voltage or boosting performance, and it isn’t the same as grounding—grounding provides a path to earth for fault currents and a reference potential, while bonding keeps metallic parts at equipotential with each other. Bonding is needed for many components (enclosures, piping, and other metal structures) to maintain safety and ensure proper operation of protective devices.