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h

Figure 5.1.2.1 Air-termination system on a Figure 5.1.2.2 Height of a roof-mounted struc- Figure 5.1.2.3 Additional air-termination
gable roof ture made of non-conductive system for vent pipes
material (e.g. PVC), h ≤ 0.5 m

In order to prevent these partial lightning currents, isolated air- Generally, the metal gutter is used for closing the “mesh” of
termination systems must be installed for such roof-mounted the air-termination system on the roof surface. If the gutter
structures. itself is connected in such a way that it is conductive, a gutter
The isolated air-termination system can be designed using the clamp is mounted at the cross point between the air-termina-
rolling sphere or protective angle method. An air-termination tion system and the gutter.
system with a mesh size according to the class of LPS used can
be installed if the whole arrangement is elevated (isolated) by Roof-mounted structures made of non-conductive material
the required separation distance s. (e.g. PVC vent pipes) are considered to be sufficiently protect-
ed if they do not protrude more than h = 0.5 m from the plane
A universal component system for installing isolated air-termi- of the mesh (Figure 5.1.2.2).
nation systems is described in chapter 5.1.8.
If such a roof-mounted structure protrudes more than h = 0.5 m,
it must be equipped with an air-termination system (e.g. air-
5.1.2 Air-termination systems for buildings
with gable roofs termination tip) and connected to the nearest air- termination
conductor. To this end, a wire with a diameter of 8 mm up
Air-termination systems on roofs include all metal compo- to a maximum free length of 0.5 m can be used as shown in
nents, e.g. air-termination conductors, air-termination rods, Figure 5.1.2.3.
air-termination tips.
The parts of the structure typically hit by lightning strikes Metal roof-mounted structures without conductive connection
such as gable peaks, chimneys, ridges and arrises, the edges into the structure do not have to be connected to the air-ter-
of gables and eaves, parapets and other protruding structures
mounted on the roof must be equipped with air-termination mination system if all of the following conditions are fulfilled:
systems. ¨ Roof-mounted structures may protrude a maximum dis-
tance of 0.3 m from the roof level
Normally, a meshed air-termination network is installed on the ¨ Roof-mounted structures may have a maximum enclosed
surface of gable roofs with a mesh size according to the class of area of 1 m (e.g. dormers)
2
LPS (e.g. mesh size of 15 m x 15 m for class of LPS III) (Figure ¨ Roof-mounted structures may have a maximum length of
5.1.2.1).
By using the ridge and the outer edges as well as the met- 2 m (e.g. sheet metal roofing)
al parts serving as an air-termination system, the individual Only if all three conditions are met, no connection is required.
meshes can be positioned as desired. The air-termination con- Furthermore, the separation distance to the air-termination
ductors on the outer edges of the building must be installed as and down conductors must be maintained for the above men-
close to the edges as possible. tioned conditions (Figure 5.1.2.4).

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