Hardware on wood transmission structures operating above 230KV is bonded above the top of the X brace. Why is this bonding done?

• A. To complete the grounding circuit
• B. Eliminates corona and radio noise from the line
• C. To increase the paths to ground for transient over voltages
• D. To eliminate air gaps where arcing might develop and cause fires

Answer: (D)

Bonding the hardware above the X-brace on very high voltage wood structures is done to prevent arcing across air gaps and the chance of a fire starting. At voltages like 230 kV and higher, small gaps between energized metal parts and the wood structure or surrounding hardware can break down and allow a spark to jump, especially during faults or lightning. By bonding those components to the structure, they are kept at essentially the same electrical potential, removing the voltage difference that would drive an arc through the air. This is about reducing the risk of arcing-induced fires, not about completing a grounding circuit, eliminating corona, or creating more ground paths.