NEC is the National Electrical Code (NFPA 70), published by the National Fire Protection Association. It covers all aspects of electrical installation in building structures. Of particular interest to the CB community is Article 520 of the NEC: Theaters, Audience Areas of Motion Picture and Television Studios, and Similar Locations. Link to website of NFPA.
Note: 2008 National Electrical Code® Softbound is $85; 2008 NEC Handbook on CD-ROM is $210. Either is a worthwhile investment, but for the financially-challenged, an online reader for all NFPA documents is available at http://www.nfpa.org/freecodes/free_access_document.asp?id=7008SB.