Chapters, articles, parts and sections

On her first night of study Dana does something she has never done in eleven years of using the Code: she reads the table of contents from beginning to end. It takes forty minutes. By the end she can see the book as a building with floors and rooms, instead of a pile of pages she opens at the place she happens to remember. This lesson walks through that structure, from the nine chapters down to the smallest numbered list item, so that every citation you see becomes an address you can find.

Article 90 and the arrangement of the Code

Article 90, the introduction, does more than state the purpose of the Code. Section 90.3 explains how the chapters relate to each other, and that one section saves more exam time than any other once you understand it. In the 2023 edition the arrangement works like this. Chapters 1 through 4 apply generally to all electrical installations. Chapters 5, 6 and 7 apply to special occupancies, special equipment and special conditions, and they can supplement or modify the general rules in Chapters 1 through 7. Chapter 8 covers communications systems and in the 2023 edition stood largely on its own, applying the earlier chapters only where it referred to them. Chapter 9 contains tables that apply where the rest of the Code refers to them. The informative annexes that follow are not part of the requirements at all; they are there to help you.

The practical consequence is the most important navigation habit in this course: when an installation is in a special occupancy, uses special equipment or involves a special condition, look in Chapters 5, 6 or 7 first, because a rule there can change what Chapters 1 through 4 would otherwise require. A receptacle near a swimming pool, a branch circuit in a hospital patient room, a sign outline lighting circuit or a fire pump feeder are all governed first by their own articles. If you start in Chapter 2 you may find a correct general rule and still pick the wrong answer.

The 2026 edition changed the wording of 90.3 and moved most of the old Chapter 8 material into Chapter 7, so that communications systems are no longer treated as separate from the rest of the Code, and the titles of Chapters 5, 6 and 7 now say specific rather than special. The idea is the same, general rules first and then the rules that modify them, but if your exam is on 2026 the chapter boundaries you tab will be slightly different. Lesson 10 covers the edition changes in detail.

The nine chapters

You do not need to memorize every article number, but you should know which chapter holds which kind of rule well enough to open the book within a few pages of your target on the first try. Here is the 2023 layout with the articles master candidates use most.

Look at the pattern within Chapters 2 and 3. Chapter 2 moves roughly in the order power flows backwards from the outlet: branch circuits, feeders, load calculations, outside circuits, services, then the protection and grounding that apply to all of them. Chapter 3 begins with general rules for all wiring methods in Article 300 and conductors in Article 310, then boxes and enclosures, then the individual cable and raceway articles in a fixed format. Once you see these patterns you can often guess the right article before you check the contents.

Articles and their parts

Each chapter is divided into articles, and each article covers one subject. Article 250, for example, is all about grounding and bonding. Large articles are divided into parts, numbered with Roman numerals, and the parts give you a second level of address. Article 250 has parts for general requirements, system grounding, the grounding electrode system, enclosure grounding, bonding, equipment grounding conductors and more. Article 230 has parts for overhead and underground service conductors, service-entrance conductors, service equipment, disconnecting means and overcurrent protection.

Parts matter for two reasons. First, they let you narrow your search: if a question is about the service disconnect, you can go straight to the disconnecting means part of Article 230 instead of reading from 230.1. Second, some rules apply only within their own part. A section in one part may begin by saying that the part applies only to certain systems, for example installations over a certain voltage, and that limits every rule that follows. Reading the scope statement at the start of a part is a habit worth building.

Article 430 is the classic example of a well-organized article. Its parts follow the motor circuit from the feeder down to the motor: feeder protection, branch-circuit short-circuit and ground-fault protection, conductors, the controller, overload protection, the disconnecting means. The article even includes a diagram that shows which part covers which component. Master exams lean heavily on motor questions, and candidates who know the parts of Article 430 can answer most of them in a minute or two. MELU-105 covers motors in depth.

The uniform layout of wiring method articles

The articles in Chapter 3 for individual cables and raceways all follow the same section numbering, which is one of the Code's best navigation aids. The last digits of each section number tell you the subject, whatever the article. Once you learn the pattern for one wiring method, you know where to look in all of them.

This is why an experienced candidate can answer 'What is the maximum number of quarter bends between pull points in a run of rigid PVC conduit?' without using the index. The question is about bends in one run, so the section ends in .26, and PVC conduit is Article 352, so the answer is in 352.26. The same logic finds support intervals for EMT in 358.30, or uses not permitted for nonmetallic-sheathed cable in 334.12. Dana writes the pattern on an index card and practices until she no longer needs the card.

# Build a section number from the uniform Chapter 3 layout
articles = {"RMC": 344, "IMC": 342, "PVC": 352, "EMT": 358, "NM cable": 334, "MC cable": 330}
subjects = {"uses permitted": 10, "uses not permitted": 12, "number of conductors": 22,
            "bends in one run": 26, "securing and supporting": 30}

def section(method, subject):
    return f"{articles[method]}.{subjects[subject]}"

for method, subject in [("PVC", "bends in one run"), ("EMT", "securing and supporting"),
                        ("NM cable", "uses not permitted")]:
    print(f"{method:9} {subject:24} -> {section(method, subject)}")

PVC       bends in one run         -> 352.26
EMT       securing and supporting  -> 358.30
NM cable  uses not permitted       -> 334.12

Sections and their subdivisions

Below the article and part comes the section, the basic unit of a rule. A section number has two pieces separated by a period: the article number and the section number within it. 210.8 is Article 210, section 8. Sections are then divided into lettered and numbered subdivisions, and the format is consistent across the Code.

The deeper you go, the narrower the rule. 210.8 covers ground-fault circuit-interrupter protection for personnel in general. 210.8(A) narrows it to dwelling units. 210.8(A)(6) narrows it further to one location within a dwelling unit. When an exam answer cites a subdivision, the parent text above it still applies: the conditions in 210.8 and 210.8(A) are part of the rule in 210.8(A)(6). Lesson 8 returns to this point, because forgetting the parent text is one of the most common reading errors.

Sections also have titles, usually in bold, and many subdivisions have short titles too. The titles are not rules in themselves, but they are excellent signposts. When you scan a long article, read the bold titles and skip the text until a title matches your question.

Lists, tables and figures inside articles

Within sections you will find numbered lists, tables and occasionally figures. A list may mean all of the items apply, or any one of them, and the introductory sentence tells you which: watch for words such as all of the following, any of the following or one of the following. Tables inside an article are numbered after the section that introduces them. Table 110.26(A)(1), for instance, is the table that goes with 110.26(A)(1), and Table 310.16 goes with section 310.16. This makes tables easy to find from their number alone. Figures are numbered the same way and are usually explanatory.

Chapter 9 tables are numbered differently, simply Table 1, Table 4, Table 5 and so on, and they come with notes that are part of the table. Lesson 5 is devoted to tables, including how to read the notes and footnotes that change the meaning of the numbers.

Putting the address system to work