General Code Requirements, Definitions, and Wiring Design
Reading the Code the way the exam does
Article 90 sets the scope: the NEC is a minimum installation standard, not a design manual. Chapters 1–4 apply generally, 5–7 cover special occupancies, conditions, and materials, Chapter 8 covers communications, and Chapter 9 holds the tables. Annexes and Informational Notes are explanatory, not enforceable. Watch the wording: shall is mandatory, shall be permitted is permissive, and many questions turn on that distinction alone. Article 100 definitions settle arguments - an outlet is any point where current is taken to supply utilization equipment, a receptacle is one type of outlet device, and a device carries or controls but is not utilization equipment. Approved means acceptable to the authority having jurisdiction; listed means evaluated by a recognized testing laboratory.
Design requirements you must recognize
Article 110 requires listed equipment installed per its instructions (110.3(B)) and terminals rated for the conductor; the 60°C column applies to 14, 12, and 10 AWG unless terminations are marked otherwise. Working space at equipment (110.26) is at least 30 in wide, 36 in deep for the common condition, 6 ft 6 in high, with dedicated equipment space above. Know where the branch-circuit rules (210), overcurrent rules (240), grounding rules (250), and wiring-method rules (300) live so you can locate a rule quickly under time pressure.
Trap: ampacity adjustments for temperature and conductor count are applied before you compare the result to the overcurrent device.
Worked example: a 30 A continuous load requires 125% sizing - 30 × 1.25 = 37.5 A. Conductors need at least 37.5 A ampacity and the next standard rating (240.6) is 40 A.