Fluke 1625 User Manual page 54

1625
Users Manual
1. Four earth spikes of the same length are positioned into the soil in an
even line and with the same distance "a" to each other. The earth
spikes should not be hammered in deeper than a maximum of 1/3 of
"a".
2. Turn central rotary switch to position "R
The instrument is to be wired according to picture and notices given
on the display.
A flashing of the sockets symbols EFGH or B, points to an
incorrect or incomplete connection of the measuring lead.
3. Push "START TEST" button.
4. Read out measured value R
From the indicated resistance value R
to the equation:
2 a. . R
E E
...... mean value of soil resistivity ( m)
E
R ...... measured resistance ( )
E
a ...... probe distance (m)
The measuring method according to Wenner determines the soil resistivity
down to a depth of approx. the distance "a" between two earth spikes. By in-
creasing "a", deeper strata can be measured and checked for homogenity. 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.
46
4pole".
E
.
E
, the soil resistivity calculates according
E