2 Digital Ground Resistance Tester Model 3640 and 46104.2 Ground Resistance Values .....................................................214.3 Ground Resistance Testing Principle .....................................234.3.1 Position of Auxiliary Electrodes in Measurements ......244.4 Measuring Resistance of Ground Electrodes (62% Method)..254.4.1 Auxiliary Electrode Spacing ........................................274.5 Ground Resistance Measurement Procedure (3-Point)..........284.6 Multiple Electrode System ......................................................294.7 2-Point Measurement (Simplified Measurement) ............. 314.8 Continuity Measurement .........................................................324.9 Soil Resistivity Measurements (Model 4610 Only) .................334.10 Soil Resistivity Measurement Procedure (4-Point) .................344.11 How to Use 25Ω Calibration Checker .....................................365. MAINTENANCE ............................................................................. 375.1 Warning...................................................................................375.2 Cleaning..................................................................................375.3 Replacing the Battery .............................................................375.4 Replacing the Safety Fuse......................................................38Repair and Calibration ...........................................................................39Technical and Sales Assistance ............................................................39Limited Warranty ...................................................................................40Warranty Repairs ...................................................................................40