4.1 Equipotential bonding in built-in cabinets
Equipotential bonding via meshing
The equipotential bonding between the individual control components among each
other and the central earthing bar within a metallic housing (cabinet) should
preferably be performed by meshing.
Meshing is understood to mean the conducting connection of several components,
whereby a direct conducting connection exists between all components. (See
Section 4.2, Fig. 4-1).
Points to bear in mind:
Components with metal housings must be bolted onto the cabinet housing
(assembly plate). Ensure an large-surface conducting connection.
This direct galvanized connection of the metal housing to the cabinet rear via the
component fastening bolts is only possible if the terminal at the control
large-surface galvanic connection with the fastening bearing surface of the
In the event that the control components have an insulated housing fastening or
the fastening facing consists of metallized (galvanized) plastics, the connection
between the equipotential bonding terminal of the component and the cabinet
housing must be provided ≥ via a short equipotential bonding line 10 mm
(see Section 4.2 Fig. 4-1, component 3).
The connection between the central earthing bar and the cabinet housing must
be low-resistance, short and with a large surface area.
All contact surfaces for earth connections must be metallically bare. It is
absolutely essential to remove the oxide and colour coat permanently.
The corrosion resistance of the earth connections must be ensured, particularly
in respect of contact corrosion and resistance against external influences.
) for the equipotential bonding line has a
EMC Installation Guideline – Planning Guide (EMV) – 03.2004 Edition
© Siemens AG, 2004. All rights reserved