General Requirements, Definitions, and Inspection (NEC Articles 100, 110)
Article 100: the definitions carry points
Article 100 punishes candidates who read fast. Learn the near-pairs: a grounded conductor is the current-carrying neutral; a grounding conductor is the equipment grounding conductor that carries no current except during a fault. Bonding joins metal parts into a conductive path; grounding connects to earth. A receptacle is an outlet device; a switch is a device but not an outlet. Utilization equipment does mechanical, chemical, heating, or similar work - not information processing.
Article 110: rules that always apply
110.3(B) makes listing and labeling instructions enforceable. 110.12 requires workmanlike installation. 110.14 covers terminations: torque values, no shared terminals for grounded and grounding conductors, and the 75°C limitation where terminations are unmarked. 110.16 arc-flash labeling and 110.24 available-fault-current labeling at services appear often as one-line items. Article 110 also covers examination, mounting, and the integrity of electrical equipment.
The working-space trap
Table 110.26(A)(1) clear depth depends on voltage and on the condition of the space, not on equipment rating. Condition 3 (exposed live parts on both sides of the aisle) adds depth over Condition 1. Width is 30 in or the width of the equipment, whichever is greater; height is 6½ ft; dedicated equipment space extends 6 ft above the equipment and to its full width and depth.
Worked rule: a 480 V panel facing a blank wall is Condition 1 → 36 in. If another 480 V panel with exposed live parts faces it across the aisle, you are in Condition 3 → 48 in. Questions offering 36 in as a universal answer are testing exactly this.