If I had to pick out one book—NEC Handbook published by the NFPA. Second would be McPartland’s NEC Handbook published by McGraw-Hill. Don’t want to discourage anyone, but unless you have a year to prepare, it’s a tough task. The best would be to familiarize yourself with how the Code is organized and indexed—mainly to know where to find specifics. Code terminology is its own sort but critical. Even senior people have to look up details, so in a job interview the best answer may be something like, “Motor overload protection—I’d start in chapter 4 (or article 430) depending upon familiarity with the book. Having a photographic memory of technical details helps.
