This book sets out to provide a basic grounding in the design of electrical services for buildings. It is intended for students of building services engineering in universities and polytechnics but will also be useful to graduates in mechanical and electrical engineering who are about to specialize in building services after obtaining a more broadly based, first degree. The emphasis throughout is on the needs of a design engineer rather than on those of an installation electrician or of an architect. Engineering is one discipline, but with the increasing number of specialized first degree courses, the requirements for greater flexibility among engineers within industry have increased commensurably; many young graduates find themselves called on to work in fields not fully covered in their studies. In spite of the many opportunities which now exist for continuing professional education there is still a lack of books to bridge the gap between the theoretical texts and the unwritten experience of one’s predecessors. It was in the hope of meeting this need that I originally wrote this book, and I believe the need still exists sufficiently to justify this new edition.