General Electrical Knowledge and Code Administration
How the code is organized
The NEC is arranged in nine chapters. Chapters 1 through 4 contain general rules that apply unless another article modifies them. Chapters 5 through 7 address special occupancies, special equipment, and special conditions. Chapter 8 covers communications systems, and Chapter 9 contains tables and annexes. Article 90 states the scope and enforcement framework, Article 100 defines terms used throughout, and Article 110 gives general installation requirements. Kentucky adds licensing, permit, and inspection requirements enforced by the authority having jurisdiction.
Reading the language carefully
A rule using shall is mandatory. A rule using shall be permitted is permissive. Informational notes explain or give examples but are not enforceable requirements. Listed or labeled equipment must be installed according to its listing and instructions under 110.3(B). Questions often test whether a rule is mandatory or permissive, whether a definition changes ordinary meaning, and whether manufacturer instructions add a requirement.
Trap and worked example
A common trap is ignoring product instructions because a general code rule seems more permissive. If a listed luminaire is marked for 90°C supply conductors, the branch-circuit conductors at the luminaire must be rated at least 90°C even when the panel terminals are rated 75°C. The conductor ampacity must still be limited by the lower terminal rating for the circuit. Rule of thumb: shall means mandatory, permitted means optional, and a note is guidance only.