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.