Some good books for electricians starting out in the trade include "Applications of Electrical Construction," the annually released "National Electrical Code Handbook" and "Practical Electrical Wiring." Each of the books covers a range of topics necessary to understand the electrician trade.
The "National Electrical Code Handbook" explains the legal codes to which electricians must adhere while working in most jurisdictions, as well as the basics of the trade.
"Applications of Electrical Construction" dives further into the theory of electricity than the handbook but also includes directions for everyday electrical tasks.
"Practical Electrical Wiring" provides examples and guidelines for residential and commercial electrical wiring tasks, along with an overview of the National Electrical Code.