User's Guide _______________________________________________________________________ 
28  ___________________________________________________________________ M211107EN-C 
Equipment Grounding and Lightning Protection 
The power supply cable with its protective earth conductor (PE) provides 
a standard protective ground for the AC (mains) power supply inside the 
interface unit. A 3-conductor AC cable with a proper earth conductor 
grounding must be used. 
Equipment grounding protects the electrical modules of FS11P against, 
for example, lightning and prevents radio frequency interference. 
Equipment grounding for the FS11P sensor is done with a jacketed 
grounding cable and conductive grounding rod(s). 
The enclosure of the FSI102 interface unit should be grounded using the 
grounding clamp located under the cable flange (see Figure 4 on page 
29). A 16 mm
2
 
jacketed grounding cable should be connected to the 
clamp. 
In case of a frangible mast, the FSM102 Measurement Unit is also 
grounded with a 16 mm
2
 
jacketed grounding cable that is located inside 
the mast. 
Depending on the need, one to four copper-sheathed steel rods are driven 
into the ground. In case several rods are needed, the alignment from the 
foot of the base plate must be radial. 
The grounding principles are as follows: 
-  Install the grounding rod as close to the pole mast as possible, to 
minimize the length of the grounding cable. The grounding cable can 
also be cast inside the concrete base. 
-  The length of the grounding rod depends on the local groundwater 
level. The lower end of the grounding rod should continuously touch 
moist soil. 
The quality of the grounding can be checked with a georesistance meter. 
The resistance should be less than 10 Ω. 
NOTE 
Make the grounding cable long enough to allow the mast to tilt properly.