22
H
S
E
H
S
d
2
d
1
If you find the same values, your measurement is reliable. If the measured values are substantially different, it is probable that
they were influenced by earth currents or a groundwater artery. It may be useful to drive the rods deeper.
If the in-line configuration is not possible, you can plant the rods in a triangle. To validate the measurement, move the S rod on
either side of the line HE.
H
S
E
S
Avoid routing the connecting cables of the earth rods near or parallel to other cables (transmission or power supply), metal pipes,
rails, or fences, this in order to avoid the risk of cross-talk with the measurement current.
52% d
d
62% d
72% d
H
S
3.5.5. VALIDATION OF THE MEASUREMENT
To validate your measurement, move the S rod towards the H rod by 10% of d and make another measurement. Then move the
S rod, again by 10% of d, but towards the earth electrode.
The 3 measurement results must be the same to within a few percent. If this is the case, the measurement is valid. If not, it is
because the S rod is in the zone of influence of the earth electrode.
If the resistivity of the ground is homogeneous, it is necessary to increase distance d and repeat the measurements. If the re-
sistivity of the ground is inhomogeneous, the measurement point must be moved either towards the H rod or towards the earth
terminal until the measurement is valid.
3.5.6. POSITIONING OF THE AUXILIARY RODS
To make sure that your earth measurements are not distorted by interference, we recommend repeating the measurement with
the auxiliary rods placed at a different distance and in another direction (for example rotated 90° from the first alignment).
