Fluke Fluke 4325181 User Manual
Product codes
4325181
Earth/Ground Tester
Advanced Operation
33
4. Read out measured value R
E
.
From the indicated resistance value R
E
, the soil resistivity calculates according to the
equation:
E
E
R
a.
.
2
π
ρ
=
ρ
E
...... mean value of soil resistivity (
Ω
m)
R
E
...... measured resistance (
Ω
)
a
...... probe distance (m)
The measuring method according to Wenner determines the soil resistivity down to a
depth of approximately the distance "a" between two earth spikes. By increasing "a",
deeper strata can be measured and checked for homogeneity. By changing "a" several
times, a profile can be measured from which a suitable earth electrode can be
determined.
depth of approximately the distance "a" between two earth spikes. By increasing "a",
deeper strata can be measured and checked for homogeneity. By changing "a" several
times, a profile can be measured from which a suitable earth electrode can be
determined.
According to the depth to be measured, "a" is selected between 2 m and 30 m. This
procedure results in curves depicted in the graph below.
procedure results in curves depicted in the graph below.
Distances of Probe
Soil restivity ρE
A
2
1
3
edw021.eps
Curve 1:
As
ρ
E decreases only deeper down, a deep earth electrode is advisable.
Curve 2:
As
ρ
E decreases only down to point A, an increase in the depth deeper
than A does not improve the values.