AEMC 4500 - Auxiliary Electrode Spacing

28 Digital Ground Resistance Tester Model 4500
either side of the initial Y setting are most likely to be within the established
toleranceband.Thistolerancebandisdenedbytheuserandexpressed
as a percent of the initial reading: ± 2%, ± 5%, ± 10%, etc.
Resistance
Distance from Y to Ground Electrode
Effective
Resistance
Areas Do
Not Overlap
XY
Z
Ground
Electrode
Under Test
Auxiliary
Potential
Electrode
Auxiliary
Current
Electrode
D
62% of D
Resistance of
Auxiliary Current
Electrode
Resistance of Earth Electrode
Figure 14
4.4.1 Auxiliary Electrode Spacing
NodenitedistancebetweenXandZcanbegiven,sincethisdistanceis
relative to the diameter of the electrode tested, its length, the homogeneity
of the soil tested, and particularly, the effective resistance areas. However,
an approximate distance may be determined from the following chart
which is given for a homogeneous soil and an electrode of 1" in diameter.
(For a diameter of 1/2", reduce the distance by 10%; for a diameter of 2"
increasethedistanceby10%.)
Approximatedistancetoauxiliaryelectrodesusingthe62%method:
Depth Driven Distance to Y Distance to Z
6 ft. 45 ft. 72 ft.
8 ft. 50 ft. 80 ft.
10 ft. 55 ft. 88 ft.
12 ft. 60 ft. 96 ft.
18 ft. 71 ft. 115 ft.
20 ft. 74 ft. 120 ft.
30 ft. 86 ft. 140 ft.