NFPA 70, National Electrical Code (NEC), is the authoritative document addressing electrical installations in residential, commercial, and industrial settings.\u202FThe NEC is\u202Frevised every three years to stay in sync with industry practices, emerging trends, and the development and introduction of technologies to provide comprehensive rules for designers, installers, inspectors, engineers, electricians, and anyone else who works in the electrical industry. The code is organized for ease of use.