NEC Practice Test

Code questions on ampacity, overcurrent protection, grounding, conduit fill, GFCI and working space — each citing the article it comes from.

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Every question cites its article so you can look it up
No NEC table is reproduced, only values you need to work a problem
Instant feedback with the reasoning behind each answer

Which code edition these questions use

Code-specific questions here are written to the 2017 edition of the National Electrical Code, because that is the most recent edition published as a citable public document, through Public.Resource.Org's publication of standards incorporated by reference. Every such question is tagged with its edition and cites the article or table it comes from.

Your examination may use a different edition. Texas examinations have been referenced to the 2026 NEC since 1 September 2026, and the North Carolina Board publishes the 2020 NEC for its exams. Confirm the edition in your licensing authority's candidate bulletin, and verify any value you intend to rely on against that edition.

How much does the edition actually change?

Most of what is tested here has been stable across recent editions: ampacity, standard device ratings, conduit fill percentages, box fill allowances and motor full-load currents. Article numbering and specific requirements do change, and we do not claim otherwise. No NEC table is reproduced on this site; where a question needs a table value, that single value is supplied in the question itself.

How the National Electrical Code is organised

The Code has nine chapters, and knowing how they relate to one another is what lets you find a rule in seconds instead of minutes. Chapters 1 through 4 apply generally. Chapters 5, 6 and 7 deal with special occupancies, special equipment and other special conditions, and they may supplement or modify the general chapters — so a rule for a swimming pool or a health care facility can override what Chapter 2 says. Chapter 8 covers communications systems and stands apart from Chapters 1 through 7 except where a Chapter 8 rule specifically references them. Chapter 9 is tables, applicable where they are referenced.

The practical consequence on exam day is that a question about a dwelling kitchen receptacle is answered from Chapter 2, while the same question about a marina sends you to Chapter 5 — and the Chapter 5 answer wins.

Chapters of the National Electrical Code
Chapter	Covers	Applies
1 — General	Definitions, requirements for electrical installations	Generally
2 — Wiring and Protection	Branch circuits, feeders, services, overcurrent, grounding	Generally
3 — Wiring Methods and Materials	Conductors, raceways, cables, boxes	Generally
4 — Equipment for General Use	Cords, switches, receptacles, luminaires, motors, transformers	Generally
5 — Special Occupancies	Hazardous locations, health care, marinas, mobile homes	May modify 1-7
6 — Special Equipment	Signs, lifts, pools, solar, fuel cells	May modify 1-7
7 — Special Conditions	Emergency systems, standby, fire alarm, fibre optic	May modify 1-7
8 — Communications Systems	Telephone, radio, TV, network cabling	Independent of 1-7
9 — Tables	Conduit fill, conductor dimensions, conductor properties	As referenced

The code areas that carry the most marks

Across the published outlines, these are the areas worth the most. Each links to a page that explains the method before testing you on it.

Branch circuits and conductors. The single largest block on the Texas journeyman knowledge portion at 10 of 56 items. Ampacity tables, termination temperature limits, correction and adjustment factors, and the small-conductor overcurrent limits. Practise wire sizing and ampacity.
Wiring methods and materials. Tied for largest at 10 items, and 26 percent of the National Standard journeyman outline — the biggest single area there. Burial depths, raceway types, box fill, flexible cord rules.
Services, service equipment and separately derived systems. Dominant on the master exam, at 11 of 70 knowledge items and 8 of 30 calculations items. Load calculations, service disconnects, the main bonding jumper. Practise load calculations.
Grounding and bonding. Two different sizing tables that candidates routinely confuse, plus the electrode requirements and the effective ground-fault current path. Practise grounding and bonding.
Equipment and devices. Receptacles, switches, luminaires, HVAC equipment, appliances and working space clearances.

How to use your code book in an open-book exam

1. Tab the tables you will use every time. The ampacity table, the standard device rating table, the equipment grounding and grounding electrode conductor tables, the motor full-load current tables, and the Chapter 9 conduit and conductor tables. Check your jurisdiction's rules on binding first — Texas permits any soft-bound NEC but bars loose-leaf, spiral and ring-bound copies.
2. Learn the index and the table of contents, not just the tabs. When a question uses unfamiliar wording, the index is faster than guessing which article it belongs to.
3. Read the question for scope words. "Dwelling unit", "continuous load", "not more than three current-carrying conductors" and "over 100 amperes" each change which rule applies. These words are in the question for a reason.
4. Know your exam's conventions. Texas tells candidates to assume copper unless stated and not to apply exceptions or optional calculation methods unless the question directs them to. That second instruction prevents a lot of second-guessing.
5. Answer, flag, move on. At roughly two minutes per item there is no time to fight a hard question. Flag it, finish the ones you can do, and return with whatever time is left.

Code topics to practise

These topics are where the code questions come from.

NEC questions and answers

What does NEC stand for?

NEC is the National Electrical Code, published by the National Fire Protection Association as NFPA 70. It is revised on a three-year cycle and adopted, often with amendments, by states and local jurisdictions. Because adoption is a state matter, the edition in force where you work may be several cycles behind the newest published one.

How is the National Electrical Code organised?

The Code has an introduction and nine chapters. Chapters 1 through 4 apply generally. Chapters 5, 6 and 7 cover special occupancies, special equipment and other special conditions, and may supplement or modify the earlier chapters. Chapter 8 covers communications systems and is not subject to Chapters 1 through 7 except where specifically referenced. Chapter 9 is tables, applicable as referenced. Knowing this structure is what makes the book navigable under time pressure.

Are Informational Notes enforceable?

No. Informational Notes are explanatory material and are not enforceable as requirements. This is why the familiar 3 percent branch-circuit voltage drop figure is a recommendation rather than a rule for general branch circuits — it lives in an Informational Note. Exceptions, by contrast, are part of the rule and are enforceable.

Which NEC edition should I study for my exam?

The one your licensing authority names in its candidate bulletin, and no other. Texas examinations have been referenced to the 2026 NEC since 1 September 2026. North Carolina publishes the 2020 NEC. Buying the wrong edition is a common and avoidable mistake, and article numbering does move between editions.

Why does this site not reproduce NEC tables?

NEC text and tables are copyrighted by NFPA, which operates a formal permissions process. We cite article and table numbers, which are facts rather than protected expression, and we state requirements in our own words. Where a question needs a table value to be answerable, that single value is supplied in the question itself rather than reproduced as a table.

Is there free access to the National Electrical Code?

NFPA offers a free read-only access programme through its own portal, which requires a free account and a real browser session. Separately, Public.Resource.Org publishes editions of standards that have been incorporated by reference into law, including the 2017 NEC, as page scans at the Internet Archive. That 2017 scan is the source our code questions cite.

How much of the exam is code lookup versus memory?

Less lookup than candidates expect. The Texas journeyman NEC Knowledge portion allows about 2 minutes 20 seconds per item, which is not enough to look up more than a handful of answers. The practical approach is to know the common tables and multipliers outright and use the book to confirm the rest.