Hioki FT3151 - Page 103

39
Using the Earthing Net
Measurement on concrete surface
Because concrete is conductive, auxiliary
earthing electrodes can be installed on a
concrete surface.
Place an auxiliary earthing rod on the
concrete surface and pour water over it,
or cover the auxiliary earthing rod with
a wet cloth to form an auxiliary earthing
electrode.
If the earth resistance of the auxiliary earthing electrode is not reduced by
the above methods, place the optional 9050 Earth Nets on the concrete
surface and then position the auxiliary earthing rod on the earth net and
pour water over it. Before measurement, allow some time for the water to
well soak into the concrete.
As an alternative to the earth net, a metal plate or aluminum foil may be
used. However, the earth net will provide better reduction in the earth
resistance of auxiliary earthing electrode.
Because asphalt is insulator, it is generally not possible to install the
auxiliary earthing electrode on an asphalt surface. However, measurement
may be possible on the asphalt surface that has water permeability.
If the earthing net is not available or if it is signicantly small, a metal plate
or other conducting object can be used as a substitute, provided that it is
watered sufciently.
Model 9050 Earth Nets
1
2
3
4
5
6
7
Appx. Ind.