Electric Wiring: Domestic has for many years been acknowledged as the standard guide to the practical aspects of domestic electric wiring. It seeks to address the areas of most concern to the qualified electrician, especially design and testing. It will also be a useful addition to the resources available for students working towards NVQs or City & Guilds qualifications.
This book is also a vital reference source for many other professionals and operatives whose work demands a knowledge of electrical installations, including electrical engineers, heating engineers, architects and maintenance staff. The contents will be of value to those intending to gain a Domestic Installer Scheme Qualification which relates to Part ‘P’ of the Building Regulations. It is not intended as a DIY manual, although some non-qualified persons may find certain topics useful before calling in qualified operatives. The contents of this new edition cover current professional best practice and are fully compliant with the 17th Edition IEE Wiring Regulations.
Brian Scaddan, April 2008 Material on Part P in Chapter 1 is taken from Building Regulations Approved Document P: Electrical Safety – Duellings, P1 Design and Installation of electrical installations (The Stationery Office, 2006) ISBN 9780117036536. © Crown copyright material is reproduced with the permission of the Controller of HMSO and Queen’s Printer for Scotland.
I would like to thank Paul Clifford for his thorough technical proof reading.
The UK Generation, Transmission and Distribution System
In the early days of electricity supply, each town or city in the United Kingdom had its own power station which supplied the needs of its particular area. Standardization was not evident and many different voltages and frequencies were used throughout the country. By the time of the First World War (1914–1918), there were some 600 independent power stations in use. However, the heavy demands made by the war industry showed the inadequacies of the system and several select committees were set up to investigate possible changes.
Little was achieved until 1926, when it was suggested that 126 of the largest and most efficient power stations should be selected and connected by a grid of high-voltage transmission lines covering the whole country, and, at the same time, the frequency standardized at 50Hz. The remaining power stations would be closed down and local supply authorities would obtain their electricity in bulk from the grid, via suitable substations. The system voltage was 132 000 V (132 kV) and the supply frequency 50 Hz. On 1st April 1948, the whole of the electricity supply industry was nationalized and, in 1957, the ‘Central Authority ’ responsible for the generation of electricity was renamed the ‘Central Electricity Generating Board ’ (CEGB).
Since then, of course, the electricity industry has become privatized and the CEGB has been replaced by the National Grid Company, which buys, at the lowest price, generated electricity from such companies as National Power, PowerGen, Nuclear Electric, French Electrique and Scottish Hydro Electric. Electricity boards have become Distribution Network Operators (DNOs) and they, in turn, buy electrical energy from the National Grid Company to distribute to their own consumers.