Manual calculations are still extensively used and in particular are necessary for checking and verifying various software calculation design packages. It is highly recommended that users of such software familiarise themselves with the rudiments of these calculations prior to using the software packages.This essential book fills the gap between software and manual calculations. It provides the reader with all the necessary tools to enable accurate calculations of circuit designs. Rather than complex equations, this book uses extensive worked examples to make understanding the calculations simpler. The focus on worked examples furnishes the reader with the knowledge to carry out the necessary checks to electrical cable sizing software programmes.Other key features include:Updated information on 230 volt references and voltage drop under normal load conditions New sections on buried cables that take into account soil thermal conductivity, trenches and grouping, allowing readers to carry out accurate cables sizing Information and examples of steel wired armour cables, new to this edition. This includes sufficiency during short circuits and, for cables with externally run CPCs, gives unique fault conditions. Covers calculations of cross-sectional areas of circuit live conductors Earth fault loop impedances Protective conductor cross-sectional areas and short circuit conditions Short circuit protection. The last chapter combines all of the calculations of the previous chapters to enable the reader to complete an accurate design of an installation circuit under all conditions.A unique tool for detailed electrical installation trade, Electrical Installation Calculations, Fourth Edition is invaluable to electricians, electrical designers, installers, technicians, contractors, and plant engineers. Senior electrical engineering students and technical colleges, junior engineers, and contracts managers will also find this text useful.
Author(s): Mark Coates, Brian Jenkins
Edition: 4
Publisher: Wiley-Blackwell
Year: 2010
Language: English
Pages: 214
Electrical Installation Calculations: for Compliance with BS 7671:2008, Fourth Edition
......Page 5
About the authors......Page 9
Preface......Page 11
Acknowledgements......Page 13
Symbols......Page 15
Definitions......Page 17
1 Calculation of the cross-sectional areas of circuit live conductors......Page 23
General circuits......Page 26
Circuits in thermally insulating walls......Page 27
Circuits in varying external influences and installation conditions......Page 28
Circuits in ventilated trenches......Page 30
Circuits using mineral-insulated cables......Page 31
Circuits on perforated metal cable trays......Page 32
Circuits in enclosed trenches......Page 33
Circuits buried in the ground......Page 36
Grouped circuits not liable to simultaneous overload......Page 40
Circuits in low ambient temperatures......Page 46
Grouped ring circuits......Page 48
Motor circuits subject to frequent stopping and starting......Page 49
Circuits for star-delta starting of motors......Page 51
Change of parameters of already installed circuits......Page 52
Admixtures of cable sizes in enclosures......Page 55
Grouping of cables having different insulation......Page 61
The simple approach......Page 62
The more accurate approach taking account of conductor operating temperature......Page 65
The more accurate approach taking account of load power factor......Page 77
The more accurate approach taking account of both conductor operating temperature and load power factor......Page 80
Voltage drop in ring circuits......Page 81
Voltage drop in ELV circuits......Page 84
3 Calculation of earth fault loop impedance......Page 87
The simple approach......Page 92
The more accurate approach taking account of conductor temperature......Page 97
Calculations taking account of transformer impedance......Page 103
Calculations concerning circuits fed from sub-distribution boards......Page 104
Calculations where conduit or trunking is used as the protective conductor......Page 109
Calculations where cable armouring is used as the protective conductor......Page 116
4 Calculations concerning protective conductor cross-sectional area......Page 123
Calculations when the protective device is a fuse......Page 126
Calculations when an external cpc is in parallel with the armour......Page 133
Calculations when the protective device is an mcb......Page 135
Calculations when the protective device is an RCD or RCBO......Page 141
5 Calculations related to short circuit conditions......Page 148
a.c. single-phase circuits......Page 149
The more rigorous method for a.c. single-phase circuits......Page 157
a.c. three-phase circuits......Page 163
6 Combined examples......Page 175
Appendix: The touch voltage concept......Page 197
Index......Page 211
