Earthing Fundamental

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Earthing Techniques
1. SOIL RESISTIVITY TESTING.................................................................................................................................... 1.1 INTRODUCTION................................................................................................................................................................. 1.2 THEORY OF SOIL RESISTIVITY...................................................................................................................................... 1.3 MAKING A MEASUREMENT ........................................................................................................................................... 1.3.1 PRINCIPLES...............................................................................................................................................................4 1.3.2 SOIL RESISTIVITY TESTING PROCEDURE GUIDELINES .................................................................................. (a) Test Method.................................................................................................................................................................. (b) Selection of Test Method Type .................................................................................................................................... (c) Traverse Locations. ...................................................................................................................................................... (d) Spacing Range.............................................................................................................................................................. (e) Practical Testing Recommendations.........................................................................................................................10 2. INTERPRETATION AND MODELLING OF RESULT ...........................................................................................11 2.1 APPARENT RESISTIVITY CALCULATION................................................................................................................11 2.2 INTERPRETATION OF RESISTIVITY MEASUREMENT...........................................................................................12 3. HOW TO DESIGN A LIGHTNING EARTH SYSTEM ............................................................................................14 3.1 TYPES OF EARTH ELECTRODES ................................................................................................................................14 3.2 COMMON EARTHING SYSTEMS ................................................................................................................................14 3.3 EARTH RESISTANCE OF AN ELECTRODE - CALCULATION................................................................................16 3.3.1 Rods Driven Vertically into the Ground....................................................................................................................16 3.3.2 Rod Electrodes in Parallel .........................................................................................................................................16 3.3.3 Trench Electrodes - Horizontal Electrodes buried under the Surface........................................................................17 3.3.4 Radial Conductors .....................................................................................................................................................18 3.3.5 Ground-grid Mesh Electrodes....................................................................................................................................19 3.4 RECOMMENDED MATERIAL APPLICATIONS.........................................................................................................19 4. TESTING AN EARTHING SYSTEM ......................................................................................................................21...
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