IEEE Recommended Guide for Measuring Ground Resistance and Potential Gradients in the Earth

It is the purpose of this Guide to describe and discuss the present state of the technique of measuring ground resistance and impedance, earth resistivity, and potential gradients resulting from currents in the earth and the prediction of the magnitudes of ground resistance and potential gradients from scale model tests.1 Factors governing the choice of instruments and the techniques for various types of work are covered, such as the purpose of the measurement, the accuracy required, the time and instruments available, and the nature of the ground or grounding system under test.