Which of the following best describes why shield wires are grounded at every structure?

• A. To protect equipment from lightning only
• B. To prevent corrosion of the line supports
• C. To equalize voltage across the conductors
• D. To provide a reliable path for fault currents to the ground

Answer: (D)

The key idea is that shield wires (overhead ground wires) are there to carry surge currents safely to the earth. Grounding them at every structure creates a continuous, low-impedance path for lightning strikes and any fault current, so those surges are diverted into the ground instead of flowing into the energized conductors. This greatly reduces the voltage rise on the power lines and protects insulation, equipment, and insulators from damage.

Other options don’t capture the main purpose: grounding isn’t primarily about corrosion prevention, and while it helps limit overvoltages, it isn’t meant to equalize voltage across the conductors. The essential point is providing a reliable path for fault and lightning currents to reach the ground.