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Note the following suggestions:
If the gage is connected to a terminal box or multiplexer components such as plasma
surge arrestors (spark gaps) may be installed in the terminal box/multiplexer to provide a
measure of transient protection. Terminal boxes and multiplexers available from
Geokon provide locations for installation of these components.
Lighting arrestor boards and enclosures are available from Geokon that install at the exit
point of the instrument cable from the structure being monitored. The enclosure has a
removable top so, in the event the protection board (LAB-3) is damaged, the user may
service the components (or replace the board). A connection is made between this
enclosure and earth ground to facilitate the passing of transients away from the gage.
See Figure 4. Consult the factory for additional information on these or alternate
lightning protection schemes.
Plasma surge arrestors can be epoxy potted into the gage cable close to the sensor. A
ground strap would connect the surge arrestor to earth ground, either a grounding stake
or the rebar itself.
Terminal Box/Multiplexer
Instrument Cable
LAB-3 Enclosure
LAB-3 Board
VCE-4200
Structure
Rebars
Ground Connections
Surface
(usually buried)
Figure 4 - Lightning Protection Scheme