Electrical Installation Calculations

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.

Manual calculations are still extensively used and in particularare necessary for checking and verifying various softwarecalculation design packages. It is highly recommended that users ofsuch software familiarise themselves with the rudiments of thesecalculations prior to using the software packages.This essential book fills the gap between software and manualcalculations. It provides the reader with all the necessary toolsto enable accurate calculations of circuit designs. Rather thancomplex equations, this book uses extensive worked examples to makeunderstanding the calculations simpler. The focus on workedexamples furnishes the reader with the knowledge to carry out thenecessary checks to electrical cable sizing softwareprogrammes.Other key features include:* Updated information on 230 volt references and voltage dropunder normal load conditions* New sections on buried cables that take into account soilthermal conductivity, trenches and grouping, allowing readers tocarry out accurate cables sizing* Information and examples of steel wired armour cables, new tothis edition. This includes sufficiency during short circuits andfor cables with externally run CPCs, gives unique faultconditions.* Covers calculations of cross-sectional areas of circuit liveconductors* Earth fault loop impedances* Protective conductor cross-sectional areas and short circuitconditions* Short circuit protection.The last chapter combines all of the calculations of theprevious chapters to enable the reader to complete an accuratedesign of an installation circuit under all conditions.A unique tool for detailed electrical installation tradeElectrical Installation Calculations, Fourth Edition isinvaluable to electricians, electrical designers, installerstechnicians, contractors, and plant engineers. Senior electricalengineering students and technical colleges, junior engineers, andcontracts managers will also find this text useful.

About the authors viiPreface ixAcknowledgements xiSymbols xiiiDefinitions xv1 Calculation of the cross-sectional areas of circuit live conductors 1General circuits 4Circuits in thermally insulating walls 5Circuits totally surrounded by thermally insulating material 6Circuits in varying external influences and installation conditions 6Circuits in ventilated trenches 8Circuits using mineral-insulated cables 9Circuits on perforated metal cable trays 10Circuits in enclosed trenches 11Circuits buried in the ground 14Grouped circuits not liable to simultaneous overload 18Circuits in low ambient temperatures 24Grouped ring circuits 26Motor circuits subject to frequent stopping and starting 27Circuits for star-delta starting of motors 29Change of parameters of already installed circuits 30Admixtures of cable sizes in enclosures 33Grouping of cables having different insulation 392 Calculation of voltage drop under normal load conditions 40The simple approach 40The more accurate approach taking account of conductor operating temperature 43The more accurate approach taking account of load power factor 55The more accurate approach taking account of both conductor operating temperature and load power factor 58Voltage drop in ring circuits 59Voltage drop in ELV circuits 623 Calculation of earth fault loop impedance 65The simple approach 70The more accurate approach taking account of conductor temperature 75Calculations taking account of transformer impedance 81Calculations concerning circuits fed from sub-distribution boards 82Calculations where conduit or trunking is used as the protective conductor 87Calculations where cable armouring is used as the protective conductor 944 Calculations concerning protective conductor cross-sectional area 101Calculations when the protective device is a fuse 104Calculations when an external cpc is in parallel with the armour 111Calculations when the protective device is an mcb 113Calculations when the protective device is an RCD or RCBO 1195 Calculations related to short circuit conditions 126a.c. single-phase circuits 127The more rigorous method for a.c. single-phase circuits 135a.c. three-phase circuits 1416 Combined examples 153Appendix: The touch voltage concept 175Index 189