Communication System Manual 3WN1, 3WS1 Circuit-Breakers
Version 1.0 (02/98) Copyright Siemens AG 1998. All rights reserved. 97
4.5.2.3.1 General information on wiring arrangements
a) In cubicles and not in cubicles
It is useful to classify cables into the following cable groups and to install these groups separately in order to
comply with EMC guidelines.
ð Group A: • Screened bus and data cables (e.g. for PROFIBUS-DP, 3WN1, printers etc.)
• Screened analog cables
• Unscreened cables for DC voltages ≤ 60 V
• Unscreened cables for AC voltages ≤ 25 V
• Coaxial monitor cables
ð Group B: • Unscreened cables for DC voltages ≥ 60 V and ≤ 400 V
• Unscreened cables for AC voltages ≥ 24 V and ≤ 400 V
ð Group C: • Unscreened cables for DC voltages > 400 V
ð Group D: • SINEC H1 (Ethernet) cables
You can use the table below to look up the conditions required for installing cables based on different group
combinations.
Table 13: Cable installation regulations for combinations of cable groups
Group A Group B Group C Group D
Group A
• ‚ ƒ „
Group B
‚ • ƒ „
Group C
ƒ ƒ • „
Group D
„ „ „ •
• Cables can be installed in the same bundles or cable ducts.
‚ Cables must be installed in separate bundles or cable ducts (no minimum clearance).
ƒ Cables in cubicles must be installed in separate bundles or cable ducts. Cables not in cubicles but inside buildings must be installed in
separate cable raceways with a minimum clearance of 10 cm.
„ Cables must be installed in separate bundles or cable ducts with a minimum clearance of 50 cm.
b) Outdoors
Install cables which are not inside buildings on metal cable trays if possible. Make an electrical connection
between the joints of the cable trays and earth the cable trays.
Observe the usual lightning protection and earthing measures when installing cables outside buildings.
General guidelines:
• Lightning protection:
ð If cables and wires required for the interface are to be installed outside buildings,
measures must be implemented for internal and external lightning protection.
ð Install cables outside buildings in either
- metal conduits earthed at both ends or
- concrete cable ducts with continuous reinforcement.
ð Protect the signal cables from overvoltage by means of
- varistors or
- surge arresters filled with inert gases.
ð Install these protective elements at the point where the cable enters the building.
•• Equipotential bonding:
ð Ensure that there is sufficient equipotential bonding for the connected devices.
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