Open-Book Exam: How to Use the Code Book Under a Clock
Open book is where most candidates lose. A method for deciding what to look up, how to get to the right section in seconds, and how to read an exception without missing the condition.
An open-book exam feels like a gift until you are 40 questions in with half the time gone. The book does not answer questions for you; it answers them for people who already know where to look. This post is about becoming one of those people.
Three kinds of questions
Before you touch the book, classify the question.
Recall. You know the answer or you should: how many small-appliance circuits a kitchen needs, what GFCI protection covers in a garage, the maximum distance between receptacles along a wall. Answer it and move on. Opening the book for a recall question costs a minute and tells you nothing you did not know.
Lookup. The answer lives in a table or a specific section: the ampacity of 8 AWG THHN at 75 degrees, the grounding electrode conductor for a 200 ampere service, the minimum burial depth for PVC under a driveway. Go straight to the table. If you have to hunt for which table, that is a study gap to fix before exam day.
Calculation. A formula plus one or more table values. Flag it on the first pass and come back; these take longest and are worth no more than the others.
The fast route into the book
The index is where candidates go to die. It is alphabetical, it lists every occurrence of a word, and it sends you to three places before you find the right one. The table of contents is the fast route, and it works because the code is organised by a logic you can learn in a week:
- Chapter 1, general: definitions (100) and requirements for installations (110).
- Chapter 2, wiring and protection: branch circuits (210), feeders (215), calculations (220), outside wiring (225), services (230), overcurrent protection (240), grounding and bonding (250).
- Chapter 3, wiring methods and materials: general (300), conductors (310), boxes (314), then one article per cable and raceway type.
- Chapter 4, equipment: cords (400), switches (404), receptacles (406), appliances (422), heating (424), motors (430), air conditioning (440), transformers (450).
- Chapters 5 to 7, special occupancies, equipment and conditions.
- Chapter 9, tables: conduit fill (1, 4, 5), conductor properties (8).
Know that map and a question about a dryer receptacle sends you to 210 or 406, a question about a transformer primary to 450, a question about conductor properties to Chapter 9. Open at the article, scan the section numbers at the top of each page, and land.
Read the whole section
The exam is written by people who know where candidates stop reading. A section states a rule, then an exception, then an informational note. The question is often about the exception: the rule says the receptacle must be GFCI protected, the exception says not if it is for a dedicated appliance in a specific location, and the question describes that location. If you answer from the rule you are wrong.
Read to the end of the section before you answer. When a section refers to another section, follow the reference once; the answer is often at the end of the chain.
Tabs that earn their place
Tabs are for the places you go most, not for every article. The heavy articles (100, 110, 210, 215, 220, 230, 240, 250, 300, 310, 314, 404, 406, 430, 450), the tables you use in calculations (310.16 and the correction and adjustment tables near it, 250.66, 250.122, 430.52, 430.248 to 430.250, 450.3, Chapter 9 Tables 1, 4, 5 and 8) and Annex C. Place the tabs yourself even if they came pre-printed; placing them is a full pass through the book and the position of each one goes into your hands.
Check your state's bulletin for what is allowed: permanent tabs and highlighting nearly everywhere, handwritten notes in some states and not others, loose paper nowhere.
The drill
Twenty terms a day, with a timer. Pick them at random from the index of a study guide: working space, bonding jumper, continuous load, tap conductor, readily accessible, ampacity adjustment. Find the governing section, write down the number and the time. The first week you will average over a minute. By the third week you should be under 30 seconds, and you will notice that you no longer need the index for most of them.
On exam day
First pass: answer every recall question, flag the rest. Second pass: lookups, with a budget of two minutes each. Third pass: calculations. Last ten minutes: close the book, make sure every question has an answer. The book is a tool for the middle of the exam, not a comfort blanket for the start of it.