Central earthing bar/conductor bar
The central earthing bar or conductor bar must be connected extensively with the
supporting beams (metal-to-metal connection) and must be in direct proximity to
the cable duct. Beside the central earthing bar must be connected with a line to the
conductor system (earthing). Only in this way can error and interference currents
that arise be discharged securely.
5.3 Wiring, shielding and earthing
Wiring in groups
Power and signal lines must basically be routed separately. The different lines are
divided for this functionally into line groups. The lines of a group can be united in
common bundles and the different groups can be connected to each other with the
necessary distance (see chapter "cable running and shielding").
Basic rules for cable running
Power lines must be inserted into the cabinet at the opposite side of the signal lines
(24 volts control signals, data lines and analog signals). They should be routed in
metal ducts separately from the signal lines.
Route the control circuits for contactors (AC 230 V) separately from the signal
lines if possible.
Conduct the lines close to the cabinet earth if possible.
Related lines (forward and return conductor) must be routed together within the
For more detailed information, see the chapter "Wiring and Shielding".
Basic rules for shielding
The shield contacting must be performed immediately with the line entry into
the cabinet housing if the product-specific documentation does not prescribe a
Special shield buses should be provided for the impedance-poor shield
The cable clamp must enclose the shielding braid extensively and contact it to
achieve a good conductive connection of the shield to the cabinet earth.
Do not break the shields.
For further information, see the chapter "Cable running and shielding".
© Siemens AG, 2004. All rights reserved
EMC Installation Guideline – Planning Guide (EMV) – 03.2004 Edition
Control Cabinet Structure