Which of the following is covered by the National Electrical Code?

The National Electrical Code (NEC) is a widely adopted standard for the safe installation of electrical wiring and equipment in the United States. In an amateur radio context, the NEC dictates the rules for safe AC mains wiring, proper grounding, and the general electrical safety of your station installation. The NEC is solely concerned with preventing electrical fires and shock hazards. It does not regulate radio frequency (RF) parameters. Therefore, rules regarding acceptable bandwidth limits, modulation, and RF exposure limits are completely outside its scope. Those RF-specific regulations are handled by the Federal Communications Commission (FCC) and are detailed in Part 97 of the FCC rules.