Technical data

Chapter 2 - Installation
At the GPS Receiver Unit
After taking the precautions described previously in the antenna
installation, it should be understood that a destructive residual current
may still be present in the cable coming down from the antenna to the
GPS Receiver unit. A second lightning arrestor must be installed near
to the GPS Receiver to further dissipate any remaining lightning energy.
Where there is no access to the metal framework of the building, it is
absolutely imperative to erect a suitable lightning conductor. Failure
to do so is almost certain to result in destruction of the GPS Receiver in
the event of the antenna receiving a near lightning strike.
There are additional benefits when the GPS Receiver is mounted in a
telecommunications equipment cabinet. Such cabinets provide an
environment which affords additional protection when correctly
connected to the central earthing system of the building (main bus).
This earthing system may thereby prevent current flow between
equipment and cabinets.
When making the connection of the cabinet to the central earthing
system, ordinary round cable (of any diameter) is not an acceptable
choice and should be avoided. The preferred choice is a flat metallic
tape or ribbon of substantial width, but with a small thickness. A width
of 8cm (3 inch) is suggested, with a thickness of 1.5mm (1/16 inch).
Any compromise upon these recommended dimensions may
diminish the lightning protection.
Avoid sharp changes in direction when placing the conductor. At the
earth end use multiple connection points if at all possible. All
connections should incorporate as large an area of contact as possible.
This may be achieved by using large bolts, and washers of substantial
diameter.
A single earth stake of only about 0.7meters (2 feet) length is
insufficient, offering no real protection at all. The rod should penetrate
deep enough to reach permanently dampened earth or rock. Even then,
two such rods would offer significantly greater protection. All
connections should incorporate as large an area of contact as possible,
which is made more probable by the use of large bolts, and substantial
washers.
GPS Timing Receiver Installation and Operation Manual
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