This is a revised textbook for electrical installation work students pursuing City and Guilds Course 236, Parts I and II Certificates, and is also intended as a reference book for students on other electrical courses, particularly City and Guilds Courses 185, 201 and 232. First-year BTEC National Certificate students studying building services should also find areas of the book useful, as electricity in buildings is nowadays given high priority in terms of personal comfort and building management systems. The revisions incorporate changes in statutory and non-statutory regulations in respect of health and safety, up to and including the 16th edition of the IEE Wiring Regulations 1991.