Table of Contents
Acknowledgments xi
Author's Note to the Reader xv
Chapter 1 Introduction to BS 7671 1
Chapter 2 Part 1: Scope, Object, and Fundamental Principles 5
Chapter 3 Part 2: Definitions 7
Chapter 4 Part 3: Assessment of General Characteristics 23
Types of Conductors 23
Types of Electrical Systems 24
TN-C Systems 30
TN-S Systems 30
TN-C-S Systems 32
Chapter 5 Part 4: Protection for Safety 37
Protection Against Electric Shock, Overcurrent, Voltage Disturbances, and Electromagnetic Disturbances 37
Chapter 6 Part 5: Selection and Erection of Equipment 47
Chapter 51 Common Rules 47
Chapter 52 Selection and Erection of Wiring Systems 50
Chapter 53 Protection, Isolation, Switching, Control, and Monitoring 51
Chapter 54 Earthing Arrangements and Protective Conductors 52
TN-S Systems 53
TN-S Illustrations 54
TN-C-S Systems 58
TN-C-S Illustrations 59
TT Systems 61
TT Systems 62
TT Illustrations 63
Earth Electrodes 66
Concrete Foundations, Structural Steel Pilings, and Other Underground Metal Works 68
Soil Treatment for Earthing Electrodes 68
Earthing Electrodes for TT Systems 69
Earthing Conductors 69
Author's Note on the Selection of Earthing Conductors 70
Earthing and Bonding 70
Protective Conductors 72
Types of Protective Conductors 78
Preservation of Electrical Continuity of Protective Conductors 80
Combined Protective and Neutral Conductors 81
Earthing Arrangements (or Combined Protective and Functional Purposes 81
Earthing Arrangements for Protective Purposes 81
Earthing Requirements for the Installation of Equipment Having High Protective Conductor Currents 81
Protective Bonding Conductors 83
Main Protective Bonding Conductors 84
Supplementary Bonding Conductors 85
Chapter 7 Part 6: inspection and Testing 87
Earth Electrode Resistance 88
Earth Loop Impedance Test-General 89
Earth Loop Impedance Test (Zs) 89
External Earth Loop Impedance Test (Ze) 90
Consideration for the Increase in Resistance of Conductors with the Increase in Temperature 91
Appendix B Tables 91
Circuit Breakers 95
Minimum Protective Conductor (PE) Size 96
Temperature Correction Factors 97
Chapter 8 Electrode Calculations 99
Introduction 99
Basic Calculation Process 100
Background 102
Calculating the Estimated Resistance to Ground of Vertical Grounding/Earthing Electrodes 108
Vertical Rods in a Hollow Square (Earthing Ring) 119
Vertical Rods in a Hollow Rectangle (Earthing Ring) 121
Estimating the Resistance/Impedance of Complex Grounding Electrode Systems 126
Calculating an Estimated Ground Potential Rise of an Electrode System (Ground Grid) 130
Electrode Calculations Conclusion 132
Computer Modelling Software 132
Chapter 9 Below-Grade Earthing 135
Introduction 135
Zone (or Sphere) of Influence 136
Earthing Electrodes 137
Example Electrode Installations from the U.S. National Electrical Code (NEC) 139
Sample Protective Bonding Requirement from the U.S. National Electrical Code (NEC) 152
Earth Potential Rise 165
The Effects of Lightning on an Earthing System 176
Standards for Lightning Protection Systems 180
Chapter 10 Economic and Legal Analysis 183
Economic Considerations 183
Legal Considerations 185
Chapter 11 Managing a Grounding and Earthing Project 189
The Story 189
Lessons Learned 192
References 195
Index 197
