When installing an air terminal, the tip of the air terminal must be at least ? above the object or area it is to protect.

The requirement for the tip of an air terminal to be at least 10 inches above the object or area it is to protect is foundational in lightning protection practices. This specified height helps ensure that the air terminal effectively intercepts lightning strikes. By having the air terminal elevated above surrounding structures, it creates a preferred point for lightning to strike, thereby directing the energy safely down to the ground through the lightning protection system.

This minimum height is based on safety considerations and the physics of how lightning behaves. As lightning seeks out the highest points in its vicinity, the 10-inch elevation serves as a buffer, allowing the air terminal to be the most likely point where a lightning discharge will occur. Such a standard minimizes risks to nearby structures and individuals by improving the effectiveness of the lightning protection system.

The other height options do not meet the recommended standards set by safety and protection guidelines, thereby potentially leaving the object inadequately protected from lightning strikes.