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Moreover, supplementary protective equipotential bonding 6.2 Equipotential bonding for power
must be used for installations or installation parts of IT sys- supply systems
tems with insulation monitoring.
Supplementary protective equipotential bonding is also re- Equipotential bonding for low-voltage consumer’s installa-
quired if the environmental conditions in special installations tions as part of the internal lightning protection represents an
or parts thereof present a particular risk. extension of the protective equipotential bonding (previously:
The IEC 60364 series Part 7 draws attention to supplementary main equipotential bonding) according to IEC 60364-4-41
protective equipotential bonding for special operating areas, (HD 60364-4-41) (Figure 6.1.1).
rooms and installations. In addition to all conductive systems, the feeder cables of the
These are, for example, low-voltage consumer’s installation are also integrated in the
¨ IEC 60364-7-701 (HD 60364-7-701) Locations containing a equipotential bonding system. A special feature of this equi-
bath or shower (no longer generally required) potential bonding system is the fact that connection to the
equipotential bonding system is only possible via adequate
¨ IEC 60364-7-702 (HD IEC 60364-7-702) Basins of swim- surge protective devices. The requirements made on such
ming pools and other water basins surge protective devices are described in more detail in sec-
¨ IEC 60364-7-705 (HD 60364-7-705) Agricultural and horti- tion 7 and Annexes C and D of the IEC 62305-4 (EN 62305-4)
cultural premises standard.
Analogous to the equipotential bonding for metal installations
Minimum cross-sections for the supplementary protective (see chapter 6.1), equipotential bonding for the feeder cables
2
bonding copper conductor of 2.5 mm (in case of protected of the low-voltage consumer’s installation should also be es-
2
installation) and 4 mm (in case of unprotected installation) tablished directly at the entry point into the object. The re-
are required. quirements governing the installation of the surge protective
The difference to the protective equipotential bonding consists devices upstream of the meter of the low-voltage consumer’s
in the fact that the cross-sections of the conductors can be installation (main power supply system) are described in the
chosen to be smaller and this supplementary protective equi- guideline published by the German VDN (Association of Ger-
potential bonding can be limited to a particular location. man Network Operators) “Surge Protective Devices Type 1 –
Guideline for the use of surge protective devices (SPDs) Type 1
in main power supply systems” (see chapter 7.5.2 and 8.1)
6.1.1 Minimum cross-section for equipotential (Figures 6.2.1 and 6.2.2).
bonding conductors according to
IEC 62305-3 (EN 62305-3)
Class of LPS Material Cross-section
The cross-sections of conductors used for lightning protection 2
purposes must be dimensioned for high stress since these con- Copper 16 mm
ductors must be capable of carrying lightning currents. There- I to IV Aluminium 25 mm 2
fore, they must have larger cross-sections. Steel 50 mm 2

Irrespective of the class of LPS, the minimum cross-sections Table 6.1.1.1 Minimum dimensions of conductors connecting dif-
according to Table 6.1.1.1 must be used for connecting equi- ferent equipotential bonding bars with one another
potential bonding bars with one another and to the earth- or with the earth-termination system (according to
termination system. IEC 62305-3 (EN62305-3), Table 8)
The minimum cross-sections of equipotential bonding conduc-
tors, which allow to connect internal metal installations to the
equipotential bonding bar, can be smaller since only low par- Class of LPS Material Cross-section
tial lightning currents flow through these conductors (Table Copper 6 mm 2
6.1.1.2).
I to IV Aluminium 10 mm 2
Note: If standards provide different information on the mini- Steel 16 mm 2
mum cross-sections of conductors, the cross-sections stated in Table 6.1.1.2 Minimum dimensions of conductors connecting inter-
IEC 62305-3 (EN 62305-3) must be used for lightning protec- nal metal installations to the equipotential bonding
tion purposes. bar (according to IEC 62305-3 (EN62305-3), Table 9)

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