Page 111 - 35_DS702_E_2014_Lightning_Protection_Guide

Note: According to Table 8 of IEC 62305-3 (EN 62305-3), the Tests with a PVC-insulated copper conductor and an impulse
minimum cross-sectional area for a connecting cable between current of 100 kA (10/350 μs) revealed a temperature rise of
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two equipotential bonding bars is 16 mm (copper). 56 K. Thus, e.g. a copper cable NYY 1 x 16 mm can be used as
a down conductor or as an aboveground and buried connect-
Material Configuration Cross-sectional ing cable. This has been normal installation practice for years,
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area in [mm ] for example when installing down conductors underneath a
façade.
Solid tape 50 This is also pointed out in section 5.6.2 of Supplement 1 of the
Copper, Solid round b) 50 German DIN EN 62305-3 standard.
tin-plated copper Stranded b) 50
Solid round c) 176
Solid tape 70 5.4 Mounting dimensions for air-
Aluminium Solid round 50 termination systems and down
Stranded 50 conductors
Solid tape 50 The following dimensions (Figure 5.4.1) have proven to be
successful in practice and are mainly due to the mechanical
Solid round 50
Aluminium alloy forces acting on the components of the external lightning pro-
Stranded 50 tection system.
Solid round 176 These mechanical forces occur not as a result of the electrody-
Copper coated Solid round 50 namic forces produced by the lightning currents, but as a result
aluminium alloy of the compressive and tensile forces, e.g. due to temperature-
related changes in length, wind loads or snow loads.
Solid tape 50
The maximum distance of 1.2 m between the conductor hold-
Hot-dipped Solid round 50 ers primarily refers to St/tZn (relatively rigid). For aluminium,
galvanised steel Stranded 50 distances of maximum 1 m have proven themselves in practice.
Solid round c) 176
Figures 5.4.1 and 5.4.2 show the mounting dimensions for
Solid round 50 an external lightning protection system recommended by the
Copper-coated steel
Solid tape 50 IEC 62305-3 (EN 62305-3) standard. Wherever practical, the
Solid tape d) 50 separation distance s from windows, doors and other aper-
Solid round d) 50 tures should be maintained when installing down conductors.
Stainless steel Figure 5.4.3 shows the use of a down conductor on a flat
Stranded 50 roof.
Solid round c) 176 Other important mounting dimensions can be found in Fig-
a) Mechanical and electrical properties as well as corrosion re- ures 5.4.3 to 5.4.5.
sistance properties must meet the requirements of the future Surface earth electrodes (e.g. ring earth electrodes) are in-
IEC 62561 series. stalled around the building at a depth > 0.5 m and about 1 m
b) 50 mm (diameter of 8 mm) may be reduced to 25 mm in away from the structure (Figure 5.4.4).
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certain applications where the mechanical strength is not an
essential requirement. In this case, consideration should be The earth entry rods or connectors of foundation earth elec-
given to reduce the spacing between the fasteners. trodes (ring earth electrodes) must be protected against cor-
c) Applicable for air-termination rods and earth entry rods. For
air-termination rods where mechanical stress such as wind load rosion. Measures such as anticorrosive tapes or PVC-sheathed
is not critical, an at least 1 m long rod with a diameter of wires must be taken at least 0.3 m above and below the turf
9.5 mm may be used. (earth entry) (Figure 5.4.5). In many cases, it is easier to use
d) If thermal and mechanical considerations are important, these terminal lugs made of stainless steel (V4A). Concrete-encased
values should be increased to 75 mm . 2 fixed earthing terminals made of stainless steel (V4A) are an
aesthetically acceptable and corrosion-free connection possi-
Table 5.3.1 Material, configuration and minimum cross-sectional
area of air-termination conductors, air-termination rods, bility.
a)
earth entry rods and down conductors according to The terminal lug for equipotential bonding inside the building
Table 6 of IEC 62305-3 (EN 62305-3) must also be protected against corrosion in moist and wet rooms.

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