On structures using steel as downleads, what is the maximum average distance between grounds?

The correct answer is based on the guideline which states that when utilizing steel as downleads in a lightning protection system, the maximum average distance between grounding points should not exceed 60 feet. This limit is essential to ensure effective grounding and to provide a low-resistance path to ground for lightning currents. Steel downleads are particularly effective in conducting the hazardous high voltage and current associated with a lightning strike to the ground, thereby minimizing the potential for structural damage or personal injury.

Maintaining a distance of no more than 60 feet between grounding points enables the system to remain effective in dissipating electrical energy. If the distance were to exceed this recommended limit, the impedance of the ground connection could increase, leading to potentially dangerous voltage differentials during a lightning event. This is why following the prescribed safe spacing is critical for ensuring the overall effectiveness and safety of lightning protection systems.