For air terminals less than 24 inches tall, what is the maximum interval for placement around the perimeters of flat or gently sloped roofs?

The maximum interval for the placement of air terminals around the perimeters of flat or gently sloped roofs, when the air terminals are less than 24 inches tall, is indeed 20 feet. This spacing guideline is based on industry standards that aim to ensure effective lightning protection for structures. By placing air terminals at this interval, the system can adequately intercept lightning strikes and safely direct the discharge to the ground, minimizing damage to the building and its occupants. This standard is established to create an effective lightning protection zone, ensuring that all areas of the roof are within a suitable distance from an air terminal to maintain a low resistance path for lightning currents. This spacing reflects a practical balance between the effectiveness of the system and installation efficiency, ensuring comprehensive coverage without unnecessary redundancy.