What is the minimum height at which air terminals must be supported at a point that is not less than one-half their height?

The minimum height at which air terminals must be supported at a point that is not less than one-half their height is 24 inches. This standard is significant for several reasons.

First, it ensures that the air terminal, which is crucial for attracting lightning strikes and directing the discharge safely to the ground, is installed at a height sufficient to be effective in protecting the structure from potential lightning hazards. By requiring that the support is at least half the height of the air terminal, it stabilizes the structure and ensures that it functions effectively in all expected weather conditions.

Moreover, maintaining this minimum height helps in reducing the risk of accidental contact with the terminal, which could be dangerous. Proper installation also affects the overall efficiency of the lightning protection system, allowing the terminal to serve its purpose without interference from nearby structures or trees.

This height is established based on engineering principles that take into account the nature of lightning and the behavior of electrical discharge, making it a critical component of safe lightning protection practices.