Concrete Reinforcing Steel, Water Pipe Systems, Metallic Pathways, or Conduits SHALL NOT be used as a bonding backbone conductor.

• A. True
• B. False
• C. Not specified
• D. Sometimes allowed

Answer: (A)

In bonding practices, the main bonding backbone is meant to be a dedicated, continuous low-impedance conductor that ties all metallic parts and equipment grounds together so fault currents have a reliable path. Concrete reinforcing steel, water pipe systems, metallic pathways, and conduits cannot serve as this backbone because they’re not designed to provide a guaranteed, uninterrupted bonding path. Reinforcing steel can be interrupted by concrete placement or corrosion; water pipes can be disconnected, valved off, or insulated by coatings; metallic conduits and pathways may be modified or damaged, creating breaks or high impedance in the bond. Relying on these structural elements would lead to unpredictable bonding and potential safety issues. The correct approach is to install a properly sized bonding backbone conductor per code and use appropriate jumpers to bond other metallic components to it. Water pipes and similar systems can be bonded to the backbone, but they should not be the backbone itself.