This may well depend on just what aspects you are looking for. One of the best books I have seen is the U.S. Navy manual on basic electricity. Very good mix of practical and theoretical. I got it from Captain's Bookstore at Fishermen's Terminal in Seattle, and it might also be available on-line (??) The NEC (National Electrical Code, whichever current version) is indispensable; or its counterpart in your jurisdiction, and the Soares Book on Grounding and Bonding is also good, though a bit spendy.
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In vino veritas; in cervisia carmen; in aqua E. coli.