Navigating the NEC (2026 Article 90 and how the book is built)

In 50 minutes, your students learn how the code book is built and how to find a rule in it: which chapters apply everywhere, which ones change the others, how articles break into parts and sections, what a list, an exception, and an informational note each do, and where the definitions are. They also see how a rule moves between the 2023 and 2026 books. You teach it from this page: a class plan by minutes, a code book scavenger hunt in place of a simulation, and three questions to ask.

At a glance

Level: First-year apprentices
Time: 50 minutes, with a 90-minute variant
Sections: 90.1, 90.3, 90.4(A), 90.4(B), 90.5(A), 90.5(B), 90.5(C), 90.5(D), 90.7, 110.30, 110.31(A)(5), 120.1, 120.6, 210.1, 210.8, 210.8(A), 300.1(A), 300.6(E), 300.19(A)
Students need: Their own 2026 code book and a pencil
Edition: 2026 NEC
Last checked: October 2026

Class plan by minutes

0 to 5 minWarm-upAsk: where would you look for the rule on how many wires fit in a conduit? Take guesses by chapter and leave them on the board.
5 to 20 minBoard workTeach how the book is built on the board, through the steps to find a rule. After you cover lists and exceptions, ask students to find 210.8 and point out the rule, the exception, and the note.
20 to 35 minCode book huntPairs find six answers in their books and write the chapter, article, and section for each: the GFCI locations in a dwelling, the raceway fill rule, the definition of readily accessible, the roof deck clearance rule, the rule on loads that do not run together, and the scope of Article 210. Pairs say the path they took before they say the number.
35 to 45 minQuestionsAsk the three quiz questions below, one at a time. Students write an answer alone, then you give the answer and its section. They can use the code book.
45 to 50 minWrap-upCheck the warm-up guesses against the hunt. Ask: which step in finding a rule did you skip when you guessed?

For a 90-minute block, give the hunt 30 minutes. Add a round where each pair picks a job they did on site, finds the rule for it, and shows the class the path: chapter, article, section, then any list, exception, note, or table it pointed to.

What students learn

By the end of the period, each student can say which chapters apply generally and which can change them, tell an article from a part and a section, say what a list, an exception, and an informational note each do, find a defined word, and use the steps to find a rule they have not seen before.

90.1: Article 90 covers how the code is arranged, how its wording works, and how it is enforced.
90.3: The book is the introduction and nine chapters. The first four chapters are the general rules, Chapters 5 to 8 can add to or change the rules in Chapters 1 to 8, Chapter 9 is tables, and annexes are background only.
90.4(A): The code is written for governments to adopt and enforce.
90.4(B): The authority having jurisdiction makes the interpretations and approves equipment.
90.5(A): Mandatory rules are the ones that require or prohibit.
90.5(B): Permissive rules are options, not requirements.
90.5(C): Informational notes explain, but you cannot enforce them.
90.5(D): Informative annexes are help, not rules you must follow.
90.7: A note in this section sends you to Article 100 for the meaning of two terms it uses.
110.30: A rule can point to one part of an article and then to sections that change that part.
110.31(A)(5): A rule can point to a part of another article.
120.1: An article's scope can tell you how it splits into parts.
120.6: Where the loads-that-do-not-run-together rule sits in 2026. Per Ask Shorty's draft change list, it was 220.60 in the 2023 book.
210.1: Every article opens with a scope, and Article 210 covers branch circuits.
210.8: One section can hold a rule, an exception, and an informational note.
210.8(A): A rule can end in a list of places.
300.1(A): Other Chapter 3 articles can change Article 300.
300.6(E): Where the roof deck clearance rule sits in 2026. Per Ask Shorty's draft change list, it was 300.4(E) in the 2023 book.
300.19(A): The raceway fill rule, which sends you to a table in Chapter 9. Per Ask Shorty's draft change list, it was 300.17 in the 2023 book.

Section numbers only. Read the full text in your code book.

Quiz questions

1. You are wiring a special occupancy and find a rule in Chapter 5 that differs from a general rule in Chapter 2. What does the book say Chapters 5 to 8 can do?
Answer. They can add to or change the general rules, so the special chapter's rule can change the general one. (90.3)
2. A section ends with a line that starts with the word Exception. Where does that line fit with the rule?
Answer. It follows the rule it changes. For example, the exception in 210.8 relaxes the access rule for rooftop receptacles: they only have to be reachable from the roof. (210.8)
3. A job needs a check on how full a raceway can be. Which section holds the general raceway fill rule in the 2026 book, and where does it send you?
Answer. 300.19(A). It sends you to the fill limits in Chapter 9, Table 1. (300.19(A))

Teaching notes

Before class

Students need their own 2026 code book. Open this page on your teaching computer, and write the scavenger hunt questions from the class plan on the board. Keep the lesson to how the book is built and how to look things up. It does not teach any one rule in depth. No simulation fits this lesson, so the hands-on part is a code book hunt. For more practice with a real topic after class, send students to the simulations hub at askshorty.app/simulations.

Two discussion questions

1. Your boss quotes a rule number from memory, and it does not match what you find in your book. What do you do?
Look for: Look for students who say the book may be a different edition, and who search by topic and scope instead of by number. Per Ask Shorty's draft change list, rules move between editions (300.17 to 300.19(A), for example). The code is written for governments to adopt (90.4(A)), and the authority having jurisdiction makes the interpretations (90.4(B)).
2. You find a general rule in Chapter 2, but the job is a special occupancy. How do you know the rule is the whole story?
Look for: They should say Chapters 5 to 8 can add to or change the general chapters (90.3), so they check the special chapter before they decide.

Mistakes to watch for

Reading only the rule and skipping its exception and informational note.
Treating an informational note or an annex as a requirement.
Stopping at a general rule without checking Chapters 5 to 8 for a special place or equipment.
Reading a rule that gives a choice as if it were a requirement.
Using a rule number from an old book without checking where it went.
Skipping a pointer to a table, a part, or another article.
Guessing what a word means instead of looking it up in Article 100.

If a student’s book is a different edition

This lesson follows the 2026 NEC. The change that matters most here is in 90.3: in the 2023 book, Chapter 8 stood apart from Chapters 1 through 7 (per Ask Shorty's draft change list). In the 2026 book, Chapters 5 to 8 can all add to or change the rules in Chapters 1 to 8. Rules also moved. Raceway fill went from 300.17 to 300.19(A), roof deck clearance from 300.4(E) to 300.6(E), and the loads-that-do-not-run-together rule from 220.60 to 120.6. This comparison comes from Ask Shorty's 2023 to 2026 changes list, which is still a draft that a licensed electrician has not reviewed, so check each move in your own book. If a student has an older book, tell them to search by topic and scope, and to check which edition your authority having jurisdiction enforces.

Questions people ask

Which chapters of the NEC apply to every job?

The first four chapters are the general rules. Chapters 5 to 8 can add to or change the rules in Chapters 1 to 8 for special places and equipment, so check those chapters too (90.3).

How do you find a rule in the code book?

Name the job, pick the chapter, find the article, and read its scope (for example 210.1 for branch circuits). Then read the whole section, including any list, exception, and note, and follow every pointer to a table, part, or other article.

What is the difference between an exception and an informational note?

An exception follows a rule and changes it (the rooftop exception in 210.8). An informational note only helps you understand the rule and is not enforceable (90.5(C)).

What does shall be permitted mean?

It gives you a choice, so you may do it but do not have to. Rules that require or prohibit something are the mandatory ones (90.5(A), 90.5(B)).

Where are the definitions in the NEC?

Article 100 is where the code defines terms. Article 90 sends you there for the meaning of two terms it uses (90.7). Look up any word that matters to the rule.

Why can't I find a section number from an older code book?

Rules move between editions. Per Ask Shorty's draft change list, the raceway fill rule that was 300.17 in 2023 is 300.19(A) in 2026. Search by topic and scope, then confirm the edition your area adopted (90.4(A)) and ask your authority having jurisdiction about any interpretation (90.4(B)).

Ask Shorty is independent and is not affiliated with NFPA. Check every answer against your adopted code and your authority having jurisdiction. This lesson follows the 2026 NEC and was last checked October 2026. See something wrong? Tell us and we will check it against the code.