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NEC code map — where every rule lives

The code book is on the screen, searchable, and not yours. Open book does not mean easy — it means the exam measures how fast you find a rule. At 2:42 a question, knowing which chapter owns the answer before you start searching is most of the job. That is what this page is.

2023 NEC · the edition the exam supplies

The nine chapters

  • Ch. 1 100–110 General Definitions (100) and requirements for installations (110). Article 90, the Introduction, sits outside Chapter 1 and carries the code arrangement rule. 110.14(C) terminations and 110.26 working space are two of the most-asked rules in the book.
  • Ch. 2 200–250 Wiring and protection Branch circuits (210), feeders (215), load calcs (220), services (230), overcurrent (240), grounding and bonding (250). Article 250 is the biggest fail area — navigate it by Part, not by searching.
  • Ch. 3 300–398 Wiring methods and materials General (300), conductors and ampacity (310), boxes (314), then the raceway and cable articles. Every one of those is laid out identically, so the pattern is worth more than the individual articles.
  • Ch. 4 400–495 Equipment for general use Cords (400), switches (404), receptacles (406), panelboards (408), luminaires (410), motors (430), transformers (450). Article 430 opens with a diagram at 430.1 that tells you which Part you need — use it every time.
  • Ch. 5 500–590 Special occupancies Hazardous locations (500–506), health care (517), agricultural (547), mobile homes (550), marinas (555), temporary installations (590).
  • Ch. 6 600–695 Special equipment Signs (600), elevators (620), EV supply (625), pools and spas (680), solar PV (690), fire pumps (695). Worth real time in California: 690 and 680 are everyday work here.
  • Ch. 7 700–770 Special conditions Emergency (700), legally required standby (701), optional standby (702), interconnected sources (705), energy storage (706), fire alarm (760). Know who classifies the load and how fast power must transfer — 700 vs 701 vs 702 is a favourite.
  • Ch. 8 800–840 Communications systems Stands alone. Chapters 1 through 7 do not apply here unless a Chapter 8 rule specifically says so. Do not carry a Chapter 3 rule into a Chapter 8 question.
  • Ch. 9 Tables Tables and annexes Table 1 fill percentages, Table 4 raceway areas, Table 5 conductor areas, Table 8 conductor properties. Annex C is the biggest time-saver in the book: same-size conductors, one lookup.

Which table takes which input

14 tables

Most wrong answers on the calculation half of the exam come from running the right method against the wrong table. Table 250.66 and Table 250.122 are the pair people confuse most — one takes the size of the service conductors, the other takes the rating of the overcurrent device. This is a directory of what each table wants from you and what it hands back, which is the difference between a forty-second lookup and a four-minute hunt.

Four procedures worth running on autopilot

4 procedures

Conductor ampacity, motor branch circuits, box fill and conduit fill are each an ordered sequence, and each has one step people skip. Running them out of order produces a plausible wrong answer — which is usually sitting there as one of the four options. Each is written out step by step with the trap named.

Formulas worth memorizing

8 groups

The formulas are not in the on-screen references. This is the one part of the exam that tests recall rather than lookup, which makes it the highest-value thing to carry in with you: Ohm's law, three-phase, voltage drop, wye against delta, continuous load, transformer ratio.

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There's more below — the table directory, the four ordered procedures and the formulas worth memorizing. Create a free account for the preview: 10 flashcards, 2 formula drills a day, and the practice test. No card needed.

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Free preview · $40 for the whole thing

Free, legal sources

Both code books can be read at no cost, straight from the publishers — start there. There is nothing here worth pirating, which is the point: the free version is the whole book. Paper is a convenience, not a requirement.

If you would rather have it on paper — which edition to buy, and the one to skip.

Written by Chris Furman · last reviewed 18 September 2026

I built Electrician Cards after watching a friend prepare for this exam and discovering how much of the published advice is written for a closed-book test. I am not an electrician — everything here is researched from the candidate bulletin, the 2023 NEC's own structure, and the official content outline, and it is checked against them again whenever it changes. Always verify against the code book itself.