Siemens S7-400 Cabling Outside Buildings, Rules for EMC, Overvoltage Protection Devices

Assembling and Installing Systems

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.

Automation System S7-400	Hardware and Installation	A-19
A5E00850741-01