AEMC 4500 - Introduction to Ground Resistance Testing

Table of Contents
1. INTRODUCTION ....................................................................3
1.1 International Electrical Symbols ..................................................... 4
1.2 Receiving Your Shipment ...............................................................4
1.3 Ordering Information ......................................................................4
1.3.1 Accessories and Replacement Parts ................................4
2. PRODUCT FEATURES
............................................................6
2.1 Description .....................................................................................6
2.2 Detaching the Cover ......................................................................7
2.3 Control Features ............................................................................8
3. SPECIFICATIONS
..................................................................9
3.1 ElectricalSpecications .................................................................9
3.2 Accuracy ......................................................................................10
3.3 TableofInuencingParameters .................................................. 11
3.4 InuenceofStrayVoltage ............................................................12
3.5 InuenceofAuxiliaryResistances ...............................................12
3.6 MechanicalSpecications ............................................................13
3.7 SafetySpecications ....................................................................14
4. OPERATION
.........................................................................15
4.1 Grounding Electrode Resistance .................................................15
4.1.1 Effect of Electrode Size/Depth on Resistance ................. 17
4.1.2 Effects of Soil Resistivity on Electrode Resistance .........18
4.1.3 Factors Affecting Soil Resistivity ......................................18
4.1.4 Effect of Ground Electrode Depth on Resistance ............ 21
4.2 GroundResistanceValues ..........................................................22
4.3 Ground Resistance Testing Principle ...........................................24
4.3.1 PositionofAuxiliaryElectrodesinMeasurements .................25
4.4 Measuring Resistance of Ground Electrodes ..............................26
4.4.1 AuxiliaryElectrodeSpacing ............................................. 28
4.5 Ground Resistance Measurement Procedures ............................ 29
4.5.1 Over-range Indication ......................................................30
4.5.2 Incorrect Measurements .................................................. 30
4.6 2-Point Measurement (SimpliedMeasurement) .....................30