Page 179 - 35_DS702_E_2014_Lightning_Protection_Guide

¨ Foundation earth electrode or lightning protection earth Figure 6.1.1 shows the connections and the relevant com-
electrode ponents of the protective and lightning equipotential bonding
¨ Central heating system system.
¨ Metal water supply pipe
Earth-termination system for equipotential bonding
¨ Conductive parts of the building structure (e.g. lift rails, Since the electrical low-voltage consumer’s installation re-
steel frame, ventilation / air conditioning ducts) quires certain earth resistances (disconnection conditions of
¨ Metal drain pipe the protection elements) and the foundation earth electrode
provides good earth resistances when installed cost-effectively,
¨ Internal gas pipe
the foundation earth electrode complements the equipotential
¨ Earthing conductor for antennas (German DIN VDE 0855-300 bonding in an optimum and effective way. In Germany, the de-
standard) sign of foundation earth electrodes is governed by DIN 18014,
¨ Earthing conductor for telecommunication systems (German which, for example, requires terminal lugs for the equipotential
DIN VDE 0800-2 standard) bonding bar. More detailed information and designs of foun-
¨ Protective conductor of the electrical installation in ac- dation earth electrodes can be found in chapter 5.5.
cordance with the IEC 60364 series (PEN conductor in case
of TN systems and PE conductor in case of TT systems or If a foundation earth electrode is used as lightning protection
IT systems) earth electrode, additional requirements may have to be con-
sidered. These requirements can also be found in chapter 5.5.
¨ Metal shields of electrical and electronic conductors
¨ Metal sheaths of power cables up to 1000 V Protective bonding conductors according to
¨ Earth-termination systems of power installations exceeding IEC 60364-5-54 (HD 60364-5-54)
1 kV according to IEC 61936-1 (EN 61936-1), EN 50522 if Equipotential bonding conductors should, as long as they ful-
no impermissibly high earthing voltage can be produced fil a protective function, be labelled as protective conductors,
namely green / yellow.
Normative definition of an extraneous conductive part accord- Equipotential bonding conductors do not carry operating cur-
ing to IEC 60050-826 (HD 60050-826): A conductive part not rents and can therefore be either bare or insulated.
forming part of the electrical installation and liable to intro- The minimum cross-section of protective bonding conductors
duce a potential generally the earth potential. for connection to the main earthing busbar is:
2
¨ 6 mm (copper) or
2
Note: Extraneous conductive parts also include conductive ¨ 16 mm (aluminium) or
floors and walls if an electric potential including the earth po- ¨ 50 mm (steel)
2
tential can be introduced via them.
The minimum cross-section for earthing conductors of anten-
nas (according to IEC 60728-11 (EN 60728-11)), is 16 mm
2
The following installation parts must be integrated indirectly (copper), 25 mm (aluminium) or 50 mm (steel).
2
2
in the protective equipotential bonding system via isolating
spark gaps: Equipotential bonding bars
¨ Installations with cathodic corrosion protection and stray Equipotential bonding bars are a central component of the
current protection measures in accordance with EN 50162 equipotential bonding system and must clamp all connecting
¨ Earth-termination systems of power installations exceed- cables and cross-sections which occur in practice so that they
ing 1 kV in accordance with IEC 61936-1 (EN 61936-1), have high contact stability; they must be able to carry currents
EN 50522 if impermissibly high earthing voltages can be safely and have sufficient corrosion resistance.
produced (in rare cases) The German DIN VDE 0618-1 standard describes requirements on
equipotential bonding bars for protective equipotential bonding.
¨ Traction system earth in case of a.c. and d.c. railways in It defines the following connection possibilities as a minimum:
accordance with EN 50122-1 (tracks of Deutsche Bahn
(German Railways) may only be connected with prior writ- ¨ 1 x flat conductor (4 x 30 mm) or round conductor (Ø 10 mm)
ten approval) ¨ 1 x 50 mm 2
2
¨ Signal earth for laboratories if it is separated from the pro- ¨ 6 x 6 mm to 25 mm 2
2
tective conductors ¨ 1 x 2.5 mm to 6 mm 2

178 LIGHTNING PROTECTION GUIDE www.dehn-international.com