Chimney air terminals should be spaced so no outside corner of the chimney is more than _______ inches from an air terminal

The correct answer is 18 inches. Chimney air terminals are essential for effective lightning protection systems, ensuring that lightning energy is safely dissipated during a strike. To maximize the protection offered to the structure, it is critical that these terminals are placed within a specific distance from the edges of the chimney.

Spacing air terminals no more than 18 inches from any outside corner of the chimney helps to ensure that the lightning protection system adequately covers the entire surface area of the chimney. This proximity helps minimize the risk of side flashes, where the lightning may jump from the chimney to other conductive surfaces that are not properly protected.

While other distances like 12, 24, or 30 inches might seem reasonable, they do not conform to the standards set for optimal protection. Keeping the spacing at 18 inches provides a balanced approach, ensuring that the chimney is effectively shielded without compromising the structure's integrity.