4 Setting Up
4.1 Installation guidelines
22
Version 04 05/2014
Laying cables outside of buildings
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Warning!
It is recommended to use fiber optic cables for bus
installations which are outside of buildings. In the
case
of bus cables between buildings which are laid in
the ground, you should use a special fiber optic
cable type which is suitable for this application.
Suitable copper cable types can be used if fiber
optic cables cannot be used. Observe the
admissible minimum and maximum temperature
rating for the type of cable used.
In principle, the same rules apply to laying cables
outside of buildings as within buildings. However,
for outside installation, the cables should be
provided with additional protection by laying them
inside a suitable plastic pipe.
The transition from external to internal cables
should always use an auxiliary terminal block.
It is used to interconnect the cable for burial in the
ground with the standard bus cable. Lightning
arrestors should be installed directly where the
cable enters the building. In addition, the auxiliary
terminal block should contain appropriate circuits
to protect against overvoltages (lightning
protection).
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Fig. 7: Laying cables outside of buildings