Siemens S5-135U/155U System Manual page 39

Legend for the table
Routing of Cables
Outside buildings, lay the lines on metal cable trays if possible. Provide the
Outside Buildings joints between cable trays with an electrical connection and ground the cable
trays.
When laying lines outside buildings, you must observe the valid lightning
protection and grounding measures. The following applies in general:
Lightning
Protection
Caution
!
Where cables and lines for SIMATIC S5 controllers are to be laid
outside buildings, you must apply measures for internal and external
lightning protection.
Outside the buildings, lay your lines either
Protect the signal lines from overvoltages by means of
Fit these protective devices at the cable entry into the building.
Note
Lightning protection measures always require an individual assessment of
the entire installation. For clarification, please consult your Siemens regional
office or a company specializing in lightning protection.
Equipotential
Ensure adequate equipotential bonding between the connected equipment
Bonding
(see Section 3.3.2).
System Manual
C79000-G8576-C199-06
Lines can be laid in common bundles or cable ducts.
Lines must be laid in separate bundles or cable ducts (without
minimum clearance).
Lines within cabinets must be laid in separate bundles or cable
ducts; outside the cabinets but within buildings, they must be laid
over separate cable routes with a clearance of at least 10 cm.
Lines must be laid in separate bundles or cable ducts with a
clearance of at least 50 cm.
in metal conduit grounded at both ends,
or
in concreted cable ducts with continuously connected reinforcement.
varistors
or
inert gas-filled surge diverters.
Installation Guidelines
3-13