What is a characteristic of Class I materials in a lightning protection system?

Class I materials in a lightning protection system are specifically designed to provide optimal protection against lightning strikes. This category includes essential components such as air terminals (lightning rods) and lightning conductors, which are crucial for capturing lightning and safely directing its energy into the ground.

Air terminals are placed at the highest points of a structure to intercept lightning, while conductors provide a pathway for the lightning to travel to a grounding system without causing harm to the building or its occupants. The characterization of Class I materials in this way emphasizes their foundational role in the effective operation of a lightning protection system, highlighting safety and performance.

Other choices do not accurately represent the defining characteristics of Class I materials. For example, size, use in specific applications like underground settings, or restrictions based on the height of structures do not align with the primary function and classification of these materials in lightning protection.