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connection of the isolated connection of the isolated
air-termination system air-termination system
to the external LPS to the external LPS

2
2
4 mm Cu 4 mm Cu

multiswitch PE terminal

multiswitch
metal
DIN rail
earth
connection
MEB

earth
Figure 9.5.2 Protective equipotential bonding of the cable network connection
and the devices MEB

that they are / are not mechanically protected, the minimum
2
2
cross-section is at least 2.5 mm / 4 mm (copper). This meas- No. Surge protective device Part No.
ure is required due to the discharge currents on the mains side DEHNgate DGA FF TV 909 703
which are injected from the devices to the cable network.
For this reason, all cables entering a building (Figure 9.5.2) DEHNflex DFL M 255 924 396
must be connected to the protective equipotential bonding Figure 9.5.3 Antenna system with equipotential bonding at the
(exception: galvanic isolation of the inner and outer conduc- lowest point of the installation and surge protective
tor). If active and passive devices (e.g. amplifiers, splitters) are devices
removed, the cable shields connected to them must be inter-
connected before removing the devices and the inner conduc- Surge protection
tors must be insulated. The protection goal of the surge protective devices at the
Special attention must be paid to mains-powered devices of head-end described in the standard also applies to equivalent
protection class I connected to the cable network. If no inte-
grated TN-S system is installed, the system unbalance and the installations (Figure 9.5.3).
accumulation of the third harmonic can lead to shield currents Surge protective devices for a detached house, which are also
which can cause malfunction and fire. described in the standard, provide protection from inductive
coupling and can also be used for connections in multi-family
Internal lightning protection system houses according to the note in the standard.
An internal lightning protection system protects the content of
a building, in particular the electrical systems and electronic Antennas in buildings or underneath the roof
devices. The main function of an internal lightning protection Antenna systems in a building and antenna systems which are
system is to establish lightning equipotential bonding via the located at least 2 m underneath the roof and do not protrude
2
4 mm copper conductor and the installation of surge protec- more than 1.5 m from the wall (Figure 9.5.4) do not have to
tive devices between the inner and outer conductor to avoid be earthed via an earthing conductor. However, equipotential
sparking. bonding must be established as described before.

292 LIGHTNING PROTECTION GUIDE www.dehn-international.com