The NEC is not intended to be used as an instruction manual for untrained persons.

This means the NEC cannot be used by people who don't already have some basic understanding of the technical language used in the code.

This would include understanding the theoretical language of electrical systems, such as "current" and "voltage" and what makes up a circuit, as well as familiarity with the parts and pieces of an electrical installation.

The NEC is not intended to be used as a design specification.

Although many design specifications would require an installation to meet the National Electrical Code, such specifications are really intended to spell out other details of expected use, perhaps even restrictions on the use of the NEC.

Examples might be specific types of wiring methods to be used, a specific level of workmanship, or specific ways of doing things.