2-5
z
If the voltage is unstable, a voltage regulator or stabilizer is
required.
z
An uninterrupted power supply (UPS) is required for
uninterrupted communication.
Grounding and Lightning Protection
Table 2-5
Grounding and lightning protection requirements
Item
Requirements
Grounding
resistance
z
The grounding resistance is typically required to
be less than 5 ohms, and less than 10 ohms in an
area that has less than 20 thunderstorm days a
year. If an angle iron is to be buried into the earth
as the earthing conductor, the grounding
resistance is required to be less than 10 ohms. If
the installation site has a high earth resistance
rate, it is recommended to spray some salt water
or resistance-reducing agent on the earth around
the buried earthing conductor to reduce the
resistance rate of the earth.
z
The top of the earthing conductor should be at
least 0.7 m (2.30 ft) away from the ground
surface. In cold areas, the earthing conductor
should be buried below the frozen soil layer.