Guidance Note 5: Protection Against Electric Shock (IEE Guidence Notes) (No. 5)

CONTENTS......Page 3
ACKNOWLEDGEMENTS......Page 6
PREFACE......Page 7
INTRODUCTION......Page 8
1.2 Electric shock......Page 10
1.3.2 Electricity at Work Regulations 1989......Page 11
1.4 Philosophy of shock protection......Page 12
1.5 Protection against both direct and indirect contact......Page 13
2.1 Introduction......Page 14
TABLE 2.2 Summary of Prescribed Measures for Direct Contact Protection......Page 15
2.3 Insulation of live parts......Page 16
2.4 Barriers or enclosures......Page 18
2.5 Obstacles......Page 20
2.6 Placing out of reach......Page 21
2.7 Supplementary protection by residual current devices......Page 22
2.8 Other measures and precautions......Page 23
System......Page 25
Extraneousconductivepart......Page 26
3.2 Summary of prescribed measures......Page 27
TABLE 3.2  Summary of Prescribed Measures for Indirect Contact Protection......Page 28
3.4 Earthing......Page 29
3.5 Equipotential bonding......Page 30
3.6 Main equipotential bonding......Page 31
Fig 3.6  Illustration of main equipotential bonding......Page 32
3.7 Automatic disconnection of supply......Page 33
3.7.1 Automatic disconnection in a TN system......Page 34
3.7.2 Mixed disconnection times......Page 36
Fig 3.7.2  Final circuits having 'mixed' disconnection times (Regulation 4130213)......Page 37
3.7.3 Automatic disconnection in a TT system......Page 39
TABLE 3.7.3  Maximum values of earth electrode resistance for TT installations......Page 40
Fig 3.7.3  RCDprotected circuit in a TT system......Page 41
3.7.5 Automatic disconnection in a reduced low voltage system......Page 42
3.7.6 Automatic disconnection and portable equipment outdoors......Page 43
3.8 Use of Class II equipment or equivalent insulation......Page 44
Fig 3.8  Types of insulation......Page 45
3.8.2 Installations where Class II equipment is the sole means of protection against indirect contact......Page 47
3.9 Nonconducting location......Page 48
3.10 Earthfree local equipotential bonding......Page 50
3.11 Electrical separation......Page 51
Fig 4.1  Approximate calculation of permissible ripple content of nominal d.c. voltages......Page 54
4.2 General......Page 55
Fig 4.2  Extralow voltage systems......Page 56
4.4 PELV......Page 58
4.5 FELV......Page 59
4.6 Calculation of loop impedance PELV and FELV circuits......Page 60
5.1 Connections to earth......Page 61
Fig 5.1  System earthing arrangements......Page 62
5.2 Earth electrodes......Page 65
5.4 Main earthing terminals or bars......Page 66
5.5 Functional earthing......Page 67
5.6 Combined protective and functional arrangements......Page 68
6.1 General......Page 69
6.2 Sizing of circuit protective conductors......Page 70
7.1 Main equipotential bonding......Page 73
Fig 7.1  Main bonding of structural steelwork......Page 74
7.2 Supplementary equipotential bonding......Page 75
Fig 7.2.1  Illustrating the application of supplementary equipotential bonding in a particular location......Page 76
Fig 7.2.2  Supplementary bonding in a bathroom - metal pipe installation......Page 77
Fig 7.2.3  Supplementary bonding in a bathroom - plastic pipe installation......Page 78
TABLE 8.1  Part 6: The Increased Risks......Page 80
8.2 Supplementary and modified requirements......Page 81
8.4 Equipotential bonded floor grids......Page 82
TABLE 8.2  Special Locations - Summary of Regulations......Page 85
Fig 9.1  PME earth terminal......Page 88
Special risk outside buildings......Page 89
Fig 9.3  Schematic of a PME system with an open circuit PEN conductor......Page 90
TABLE 9.3  Additional electrode maximum resistance to earth, RA, necessary to reduce the touch voltage to 50 and 100 V......Page 91
9.4.4 Agricultural and horticultural premises......Page 92
9.4.5 Livestock/ dairies......Page 93
9.4.8 Petrol filling stations......Page 94
9.4.10 Supply terminating in a separate building......Page 95
9.4.13 High rise buildings......Page 96
APPENDIX A: MAXIMUM PERMISSIBLE MEASURED EARTH FAULT LOOP IMPEDANCE......Page 97
TABLE A1  Maximum measured earth fault loop impedance (in ohms) when overcurrent protective device is a semi-enclosed fuse to BS 3036......Page 98
TABLE A2  Maximum measured earth fault loop impedance (in ohms) when overcurrent protective device is a fuse to BS 88......Page 99
TABLE A3  Maximum measured earth fault loop impedance (in ohms) when overcurrent protective device is a fuse to BS 1361......Page 100
TABLE A4  Maximum measured earth fault loop impedance in ohms (Note 1) when overcurrent protective......Page 101
TABLE A5  Ambient temperature correction factors......Page 102
APPENDIX B: RESISTANCE OF COPPER AND ALUMINIUM CONDUCTORS......Page 103
TABLE B2  Ambient temperature multipliers(() to ......Page 104
Standard overcurrent devices......Page 105
TABLE B3  Conductor temperature factor F for  standard devices......Page 106
TABLE C1  Minimum separation distance between internal and external electricity supply cables carrying voltages in excess of......Page 108
TABLE C3  Minimum separation distance between internal low voltage electricity supply cables......Page 109
C......Page 110
F......Page 111
O......Page 112
S......Page 113
W......Page 114
Tables & figs......Page 0