P81 - Guide for Measuring Earth Resistivity, Ground Impedance, and Earth Surface Potentials of a Grounding System
The test methods and techniques used to measure the electrical characteristics of the grounding system include the following topics: a) Establishing safe testing conditions. b) Measuring earth resistivity. c) Measuring the power system frequency resistance or impedance of the ground system to remote earth. d) Measuring the transient (surge) impedance of the ground system to remote earth. e) Measuring step and touch voltages. f) Verifying the integrity of the grounding system. g) Reviewing common methods and procedures for performing ground testing. h) Reviewing instrumentation characteristics and limitations. i) Reviewing various factors that can distort test measurements.