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Use of application-optimised DEHNshield combined
arresters in low-voltage installations
When lightning hits the external lightning protection system
of a building, the lightning current is shared between the ca-
bles entering the building and the building’s earth electrode. To
prevent dangerous sparking in the structure to be protected,
the IEC 62305 (EN 62305) lightning protection standard en-
courages to take internal lightning protection measures when
installing an external lightning protection system. The standard
also requires to establish lightning equipotential bonding by
connecting all metal parts directly or, in case of power sup-
ply and information technology systems, indirectly via surge
protective devices in the structure. The surge protective devices
referred to in this standard are type 1 lightning current arrest-
ers with an adequate voltage protection level.
Application-optimised DEHNshield type 1 combined arrest-
ers combine lightning equipotential bonding up to 50 kA Figure 9.30.1 Prewired and application-optimised DEHNshield
(10/350 µs) lightning impulse currents and surge protection in combined arrester with spark gap technology
a single arrester stage. This clearly distinguishes DEHNshield
from the currently available varistor-based arresters of this ap- terminal equipment and thus ensures energy coordination with
plication and performance class. type 2 or type 3 arresters (Figure 9.30.1). Varistor-based type 1
DEHNshield arresters also provide optimal protection for build- arresters are typically not suited for energy coordination.
ings without external lightning protection system where power DEHNshield combined arresters allow cost-optimised and ap-
is supplied through an overhead line and type 1 arresters are to plication-specific design and configuration matched to a par-
be installed in the service entrance box according to the Ger- ticular application in line with recognised standards. As space
man VdS 2031 guideline. DEHNshield combined arresters can for retrofitting is confined, DEHNshield allows to establish
be used without additional backup fuse if the installation is lightning equipotential bonding wherever space is restricted.
protected by backup fuses up to 160 A. To this end, however, the parameters of the installation must be
The follow-current-limiting spark gap technology ensures se- observed as is the case when planning new installations and it
lectivity even with respect to low-value fuses (35 A gL/gG), must be checked whether DEHNshield can be used.
meaning that upstream fuses are not tripped by mains follow To make the field of application of DEHNshield more transpar-
currents. ent, some sample applications are given in the following fig-
If lightning hits external equipment (for example a camera ures.
mast), partial lightning currents will flow into the building via
the earth electrode of the external equipment and the connect- Sample applications in Figure 9.30.2
ing cables. In this context, it must be observed that these light- In order to reduce lightning currents, equipment must be di-
ning currents flowing into the building will not overload the rectly connected to earth electrodes at points where direct
surge protective device (SPD) installed in the building. lightning strikes are likely to occur (LPZ 0 A ) such as masts with
Due to their technical parameters which are suited for use in video cameras, lamp posts and under-road radiators. Cameras
simple and compact electrical installations, DEHNshield arrest- are frequently used for safety-related evaluation (monitoring
ers are an ideal solution for this field of application (Figure systems) and lamp posts are in many cases essential to ensure
9.30.1). personal protection (e.g. escape route lighting).
Therefore, the required lightning protection measures must be
What is understood by application-optimised use? taken in both cases to ensure full protection. The situation is
A type 1 arrester installed at the entrance point into the build- similar for under-road radiators, except that the area in front of
ing must be capable of carrying the partial lightning currents or next to the building is particularly prone to lightning strikes.
described above. Type 2 and / or type 3 arresters downstream of To ensure personal protection (slip hazard in case of steep en-
the entrance point into the building must be energy-coordinated trances and exits of e.g. underground car parks), failure of the
with this type 1 arrester. The follow current limiting and appli- heating system as a result of lightning strikes or surges must
cation-optimised DEHNshield combined arrester with spark gap be minimised.
technology (type 1 SPD) fulfils all these requirements. Thanks to The earth electrodes of these pieces of equipment must be in-
its wave breaker function, DEHNshield is capable of protecting terconnected. If this connection is performed in contact with

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