6.2.1.1 Air-termination rods

Air-termination rods are metal rods that serve as preferred points of strike for lightning. They are designed to prevent lightning from directly striking the structure to be protected.

They are components of air-termination systems for non-separated, separated and electrically isolated lightning protection systems. Their protected volume can be determined using the protective angle method or the rolling sphere method (chapter 4.1).

The protected volume of an air-termination rod is defined by a cone extending from the tip of the air-termination rod. The angle of the cone, the protective angle α, depends on the protection class of the lightning protection system (LPS) and the height of the air-termination rod above the reference plane. The reference plane may be the ground level or another protected horizontal surface. This has already been described in chapter 4.1 and summarised in Figure 4.1.8 and Table 4.1.4. An air-termination rod protects all parts of the structure that are within this cone.