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Measures to limit
average interference
(I n = 5 kA) – Type 2 SPD

Measures to limit
high interference
(I n = 20 kA) – Type 2 SPD

Surge protective device Part No.
DEHNcord DCOR L 2P 275 900 430
Surge protective device Part No.
DEHNshield DSH TT 255 or 941 310
DEHNcord DCOR L 2P 275 900 430 DEHNshield DSH TNS 255 941 400
DEHNshield DSH TT 2P 255 or 941 110
DEHNguard DG M TT 2P 275 952 110 DEHNshield DSH TN 255 941 200
Figure 9.15.2 Surge arrester installed next to the LED mast light Figure 9.15.3 Combined arrester installed in the terminal compart-
with the feeder cable of the mast light being installed ment / distributor of the metal mast in conjunction
in open space for protecting the LED mast light from with a surge arrester for protecting the LED mast
field-based injection or as sole protection from con- light from nearby atmospheric events and conducted
ducted surges caused by distant atmospheric events surges caused by switching operations
and switching operations

This has the advantage that the surge arrester can be tested If lightning strikes the metal mast, the mast shields the cable
without forklift. installed in it and the application-optimised combined arrester
If, however, a metal LED mast light and its metal mast do not located at the base of the mast discharges the lightning cur-
form a closed system since the feeder cable of the LED mast rent (total current up to 50 kA (10/350 μs)) across the distri-
light was placed in free space at the mast exit point and sev- bution network and protects the LED mast light by means of
eral LED mast lights are located on a mast arm, a surge ar- its low voltage protection level (Figure 9.15.3). This always
rester must be installed next to the LED mast light (Figure requires a vertical or horizontal earth electrode and an addi-
9.15.2). If the probability of surges is expected to be low, no tional surge arrester must be installed on the LED mast light
additional surge protective devices have to be installed. The
relevant protection measure used for the LED mast light must according to Figure 9.15.2, depending on the cable routing.
be considered when installing a surge arrester in the LED mast Basically, the described protection of the LED mast light by
light. Surge arresters with basic insulation (insulation of dan- means of a combined arrester must be used if a risk analy-
gerous live parts as basic protection), for example, must not sis requires a higher protection goal than a surge arrester can
interfere with the “double or reinforced insulation” (previously achieve. This is the case with extremely high masts with large-
class II) of the LED mast light according to IEC 60364-4-41 area LED mast lights on the mast arms (e.g. large parking lots,
(HD 60364-4-41). stadiums, etc.) and LED mast lights that are fed by a building
It is advisable to use DEHNcord to limit average interference with a lightning protection system since the lightning current
(I n = 5 kA). DEHNguard modular DG M TT 2P 275 should be is discharged via the lightning equipotential bonding system
installed to limit high interference (I n = 20 kA). to the LED mast light.

340 LIGHTNING PROTECTION GUIDE www.dehn-international.com