Siemens Automation System S7-400 - Manual (Page 187)

Assembling and Installing Systems
A-19
Automation System S7-400 Hardware and Installation
A5E00850741-01
A.8 Cabling Outside Buildings
Rules for EMC
When installing cables outside buildings, the same EMC rules apply as for inside
buildings. The following also applies:
• Run cables on metallic cable supports (racks, trays etc.).
• Establish a metallic connection between the joints in the cable supports
• Ground the cable supports
• If necessary, provide adequate equipotential bonding between the various items
of equipment connected.
• Take the necessary (internal and external) lightning protection and grounding
measures applying to your particular application (see below).
Rules for Lightning Protection Outside Buildings
Lay your cables either:
• In metallic conduits grounded at both ends, or
• In concrete cable ducts with continuous end-to-end armoring
Overvoltage Protection Devices
An individual appraisal of the entire plant is necessary before initiating any lightning
protection measures (see Section A.9).
Further Information on Lightning Protection
You will find further information in the following sections.