Getting Down to Earth 15the process until the whole chosen area has been covered. The location giving the lowest value for R has the lowest specific resistance for the soil to the chosen depth of 10 ft. The spot is likely to give you the best earth electrode.If you want results affected by the average earth resistivity to a depth of 20 ft, repeat the survey on lines 20 ft apart and with stakes spaced 20 ft apart. Such surveys do not require much time and can pay off in ensuring a good grounding system.Alternate Method: Another way is to drive rods or pipes in various locations to such depths as may prove practicable, testing their resistance while they are being driven. In this manner, you can usually tell at once when moisture or other good conducting earth is reached. However, the work involved is apt to be much more than with the first method.
