Vaisala FD12P - Manual (Page 32)

User's Guide _______________________________________________________________________
32 ______________________________________________________ M210296en-A
3. Power supply and communication lines must be available.
When the site for the FD12P is selected, take into consideration
the available power supply and communication lines. This
influences the amount of work and accessories needed and thus,
the actual installation costs.
Grounding and Lightning Protection
Equipment Grounding
Equipment grounding protects the electrical modules of the FD12P,
for example, against lightning and prevents radio frequency
interference. The FD12P equipment is grounded using a jacketed
grounding cable and conductive grounding rod(s).
The FD12P must be grounded by means of the grounding clamp,
which is located under the cable flange (See Figure 5 on page 33). A
16-mm² jacketed grounding cable is connected to the clamp.
Depending on the need, one to four copper-sheathed steel rods are
driven into the ground. If several rods are needed, the alignment from
the foot of the base plate must be radial.
The grounding principles are the following:
- The grounding rod must be isntalled as close to the pole mast
as possible to minimize the length of the grounding cable.
The grounding cable can be also cast inside the concrete base.
- The length of the grounding rod depends on the local
groundwater level. The lower end of the grounding rod must
continuously touch moist soil.
The grounding quality can be checked with a georesistance meter. The
resistance must be less than 10 ohms. This way the lowest possible
resistance is achieved.
The junction box must be also grounded via the grounding cables in
the same way as the electronics enclosure (Figure 5 on page 33). The
junction box is optional.