Cambium Networks PTP 250, User Manual

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PTP 250 User Guide Grounding and lightning protection
phn-2510_002v000 (Mar 2012) 2-21
Protection requirements on a high rise building
If the ODU is to be mounted on a high rise building, it is likely that cable entry is at roof
level (
Figure 16 ) and the equipment room is several floors below ( Figure 17 ). In addition to
the general protection requirements (above), the following requirements must be
observed:
x
The ODU must be below the lightning terminals and finials.
x
A grounding conductor must be installed around the roof perimeter, to form the main
roof perimeter lightning protection ring.
x
Air terminals are typically installed along the length of the main roof perimeter
lightning protection ring typically every 6.1 m (20 ft).
x
The main roof perimeter lightning protection ring must contain at least two down
conductors connected to the grounding electrode system. The down conductors should
be physically separated from one another, as far as practical.
Figure 16 Grounding and lightning protection on building
Air terminal (finial)
Tower grounding
conductor
Building ground ring
AC
service
ODU
To equipment area
CAT5e cable: gel-filled, shielded
with copper-plated steel
PTP 250 ground cables
Building ground system