Which systems must be bonded to the grounding electrode system?

• A. AC Power System Ground, Communications Tower Ground, Lightning Protection System Ground, Telco System Ground, Exposed Structural Building Steel, Underground Metal Piping
• B. Only AC Power System Ground
• C. Only Communications Tower Ground
• D. All systems must be isolated

Answer: (A)

Bonding the grounding electrode system to every system that could carry fault current or be energized creates a single reference point and a reliable fault-path back to earth. All the metallic parts listed—the AC power system ground, the communications tower ground, the lightning protection ground, the telco ground, exposed structural building steel, and underground metal piping—must be bonded to that electrode system. This unified bond minimizes potential differences between components, so a fault or a lightning surge doesn’t push dangerous voltages onto other structures or touch areas, helps protective devices clear faults reliably and quickly, and reduces shock hazards for people on the site. If any of these are left isolated from the grounding electrode system, stray currents and voltage differences can persist, leading to equipment damage, safety risks, or improper operation of protection systems.