Cable Routing Outside Buildings - Siemens SIMATIC ET 200AL System Manual

Interference-free cable routing

3.4 Cable routing outside buildings

3.4 Cable routing outside buildings
If possible, lay the cables outside buildings on metallic cable holders. Connect the cable
holder joints galvanically to each other and ground the cable holders.
Rule
Observe the following rules when laying cables outside of buildings:
● Use metallic auxiliary terminal boxes to connect cables coming from outside at the
junction to cables inside the building. Ground these boxes.
● If a crossing of cables is unavoidable, then cross the cables at an angle of 90°, if
possible, in order to keep interference from electrical fields as low as possible.
● Integrate bus cables installed outside of buildings into your lightning and overvoltage
concept.
Lightning protection
When you lay cables for SIMATIC devices outside of buildings, you have to take internal and
external lightning protection measures.
Reference
For additional information about lightning protection, refer to chapter Lightning protection and
overvoltage protection (Page 26).
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Designing interference-free controllers
Function Manual, 06/2014, A5E03461486-AB