General Electrical Knowledge, Definitions, and Code Administration
Domain 1 rewards candidates who can treat the NEC as a structured legal document instead of a pile of tables. Questions here test Article 100 definitions, the scope and arrangement rules of Article 90, and the general requirements of Article 110 that apply to every installation you will ever inspect.
How the Code is arranged
Chapters 1–4 apply generally; Chapter 5 modifies special occupancies; Chapter 6 covers special equipment; Chapter 7 special conditions; Chapter 8 communications circuits. Under 90.3, Chapter 8 stands alone - communications work need not comply with Chapters 1–7 unless a Chapter 8 article says so. Chapter 9 holds tables, and the annexes are informational only. "Shall" is mandatory, "shall be permitted" is permissive, and fine print notes explain but do not enforce.
Definitions that decide answers
- An outlet is any point where current is taken to supply utilization equipment; a receptacle is only one kind of outlet, and a switch is not an outlet.
- A multiwire branch circuit has two or more ungrounded conductors with a voltage between them and a shared grounded conductor.
- A continuous load operates at maximum current for three hours or more.
- Listed means evaluated by a nationally recognized testing laboratory; labeled means the product bears that mark; approved means acceptable to the authority having jurisdiction.
Article 110 essentials
110.26 sets working space: depth, width, and height in front of equipment, plus dedicated equipment space above switchboards and panelboards. 110.14 requires terminations rated for the conductor and tightened to the manufacturer's torque values. 110.12 requires neat and workmanlike execution, which inspectors cite more often than candidates expect.
Worked example
A 120/240 V panelboard in a garage has exposed live parts on one side and a 24 in deep storage rack in front of it. Condition 1 requires 36 in of clear depth measured from the live parts, so the rack violates 110.26(A)(1). The correction is relocating the rack, not shrinking it; the dedicated space above the panel must also stay free of ducts and piping.
Traps
Reading Chapter 8 as subordinate to Chapter 3 raceway rules; treating "approved" as a nationwide listing; checking only depth and forgetting the 30 in width and 6½ ft height; confusing GFCI with ground-fault protection for equipment.