John Whitfield 
Electrical Craft Principles, Volume 1 [PDF ebook] 

This is the first of a two-volume work covering the electrical principles syllabuses of all of the major examining bodies including the City & Guilds of London Institute”s electrical craft courses. It is also suitable for a wide range of other courses, including the first three years of the BTEC electrical series. Great care has been taken to ensure that the text fully covers the content of the syllabuses concerned, both as published and as interpreted by the examiners in the past.