Following the manufacturer's instruction, obtain a resistance reading, R, with the test set.
Convert the probe spacing, A, to centimeters. (See Page xvi for metric conversion factors.)
Compute resistivity from
Assume that a resistance of 2 ohms is measured with probe spacings of 20 feet.
Convert 20 feet to centimeters: 20 f t x 30.5 cm/ft = 610 cm
= 6.25 x 610 x 2 = 7662 ohm -cm
A = ELECTRODE SPACING
B = DEPTH OF PENETRATION < A / 2 0
D = DEPTH AT WHICH RESISTIVITY IS DETERMINED = A
Figure 1-1. Measurement of Soil Resistivity