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The cable used for making splices should be a high quality twisted pair type with 100% shielding
(with integral shield drain wire). When splicing, it is very important that the shield drain wires be
spliced together! Splice kits recommended by Geokon incorporate casts placed around the splice
then filled with epoxy to waterproof the connections. When properly made, this type of splice is
equal or superior to the cable in strength and electrical properties. Contact Geokon for splicing
materials and additional cable splicing instructions.
Junction boxes and terminal boxes are available from Geokon for all types of applications. In
addition, portable readout equipment and datalogging hardware are available. See Figure 7 for
examples. Contact Geokon for specific application information.
4.8 Electrical Noise
Care should be exercised when installing instrument cables to keep them as far away as possible
from sources of electrical interference such as power lines, generators, motors, transformers, arc
welders, etc. Cables should never be buried or run with AC power lines. The instrument cables
will pick up the 50 or 60 Hz (or other frequency) noise from the power cable and this will likely
cause a problem obtaining a stable reading. Contact the factory concerning filtering options
available for use with the Geokon dataloggers and readouts should difficulties arise.
4.9 Freezing Protection
If the water around the piezometer freezes this could damage the piezometer diaphragm causing
a large shift in the zero pressure reading. If the piezometer is to be used in locations that are
subject to freezing, Geokon can provide a special modification that will protect the piezometer
diaphragm.
4.10 Lightning Protection
In exposed locations, it is vital that the piezometer be protected against lightning strikes.
If the instruments will be read manually with a portable readout (no terminal box) a simple way
to help protect against lightning damage is to connect the cable leads to a good earth ground
when not in use. This will help shunt transients induced in the cable to ground thereby protecting
the instrument.
Terminal boxes available from Geokon can be ordered with lightning protection built in. There
are two levels of protection:
• The terminal board used to make the gage connections has provision for installation of
plasma surge arrestors.
• Lightning Arrestor Boards (LAB-3) can be incorporated into the terminal box. These units
utilize surge arrestors and transzorbs to further protect the piezometer.
In the above cases, the terminal box would be connected to an earth ground.
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