How Many Questions Are on the C-10 Exam?
The short answer
CSLB does not publish how many questions are on either exam. Not on its Examination FAQ, not in the C-10 study guide, not in the Law and Business study guide. What it does publish is enough to plan with:
| C-10 Electrical Trade | Law and Business | |
|---|---|---|
| Time allowed | 3-1/2 hours | 3-1/2 hours |
| Format | Multiple choice, four choices, one best answer | Multiple choice, four choices, one best answer |
| Reference material | None, closed book | None, closed book |
| Calculator | Provided | Provided |
| Guessing | No penalty | No penalty |
Sources: the CSLB Examination FAQ for the time, and the CSLB study guides for everything else. You have to pass both exams. Passing one does not get you a license.
If you see a precise question count quoted somewhere, ask where it came from. The one place you will see your own numbers is a failing score report, which CSLB says shows your overall score and how many questions you answered correctly and incorrectly in each section.
Closed book means closed book
Both study guides say it plainly: "This is a closed-book examination." You do not bring a code book, notes or a phone, and a calculator is provided. This matters more than any question count, because it changes how you have to study. You are not learning where to look things up. You are learning to recognize the answer.
Our walkthrough of what exam day actually looks like covers check-in, ID requirements, and the tutorial screen.
How the trade exam is weighted
The C-10 study guide splits the trade exam into five sections, and CSLB marks the percentages as approximate:
| Section | Weight |
|---|---|
| Planning and Estimating | 28% |
| Rough Wiring | 27% |
| Safety | 18% |
| Startup, Troubleshooting, and Maintenance | 16% |
| Finish Wiring and Trim | 11% |
Planning and estimating plus rough wiring is 55 percent of the exam by itself. That is where load calculations, service and feeder sizing, conductor ampacity, overcurrent protection, raceway and box fill, and wiring method selection live. If you are budgeting study hours, more than half of them belong in those two areas.
Safety at 18 percent is not a throwaway section, and troubleshooting questions ask you to reason about a circuit rather than recall a table value. Our breakdown of what is on the C-10 electrical exam goes section by section.
The trade exam is written against the 2025 California Electrical Code, which adopts the 2023 NEC with California amendments; the C-10 study guide lists it as a reference. Make sure the material you study is on that edition.
Pacing without a question count
You do not need the count to pace yourself. You need the clock.
- First pass. Answer everything you know cold. Mark anything that needs paper and math and move on.
- Second pass. Come back for the calculation questions with the time you banked.
- Third pass. Answer every remaining blank. The study guides say there is no penalty for guessing, so a blank is strictly worse than a guess.
- Checkpoints. Note how many questions the exam shows you when it starts. At the halfway mark on the clock you should be at or past the halfway mark on the questions.
CSLB's own study guides say "plenty of time is provided to answer all examination questions." Use it to read every question and all four choices completely.
Both exams, two results
You get a printed pass or fail report when you finish. A pass report does not show your score. A failing report shows your overall score and your section-by-section results, and CSLB says you can retake after 21 calendar days. Our overview of exam format and scoring explains the rest.
If you fail one and pass the other, only the failed exam is retaken. Many candidates take the Law and Business exam first, since the material is more finite; others go trade-first while their field knowledge is sharpest. Our comparison of the trade exam versus Law and Business lays out the tradeoff.
What actually moves the needle
Not a question count. Sitting with a timer, working questions on the same section weighting, and reading every explanation until the calculation methods are automatic. Timed practice questions are what turn a person who knows the trade into a person who passes the test.