Is only one air terminal required to be mounted to a chimney if it's located within 24 inches of all outside corners?

The requirement for multiple air terminals to be mounted to a chimney, even if it is located within 24 inches of outside corners, stems from the need to ensure adequate lightning protection coverage. A single air terminal may not sufficiently protect against lightning strikes, especially since energy from a lightning strike can travel laterally or reflect around corners.

When determining how many air terminals are necessary, factors such as the height of the chimney and its structure play critical roles. If a chimney is particularly tall or has protrusions, additional air terminals may be required to protect the entire structure effectively. Moreover, the placement of multiple terminals can help capture more of the electromagnetic field associated with lightning strikes, thus enhancing the protection for the chimney and any nearby structures.

Overall, the correct approach to lightning protection and meeting the standards outlined by the Lightning Protection Institute requires a thorough evaluation rather than assuming that a single terminal is sufficient. This is particularly true since the objective is to provide comprehensive safety against the unpredictable nature of lightning strikes.