C-10 Trade Exam vs. Law and Business Exam: The Two Tests You Must Pass
Almost everyone applying for a C-10 thinks about one exam: the electrical trade test. Then they find out there are two — and the second one, the Law and Business exam, is where a surprising number of skilled electricians stumble. If you want the license, you pass both. Here is exactly how the two tests differ, why the CSLB requires each, and how to prepare for them without wasting time.
Everything here explains the process to help you plan and study. Fees, formats, and rules change, so confirm the current specifics with the CSLB at cslb.ca.gov.
Two exams, one license
When the Contractors State License Board (CSLB) approves your application, it schedules you for two separate examinations:
| Exam | Scope | Who takes it |
|---|---|---|
| Law and Business | Running a contracting business legally | Every CSLB classification |
| C-10 Trade | Electrical work and the California Electrical Code | C-10 applicants only |
Both are closed-book, multiple-choice, and computer-based at a CSLB testing center. You do not bring a code book to either one. And critically: you must pass both before your license issues. For the full path from application to license number, see how to get your C-10 license.
The Law and Business exam: the same test everyone takes
Here is the part that surprises people. The Law and Business exam is identical for every contractor classification — a C-10 electrician, a B general builder, and a C-36 plumber all sit the same test. It has nothing to do with wiring. It is about running a compliant business in California.
It covers contracts and how to write and enforce them, the mechanics of a California mechanics lien and preliminary notices, employment and payroll and workers' compensation rules, business finance and bookkeeping basics, licensing law, bonds and insurance, and jobsite safety administration.
For a working electrician, this is the unfamiliar half. You use the code every day; you may have never written a change order or thought about lien deadlines. That gap is exactly why people who breeze through the trade exam get caught here. The Law and Business exam guide breaks the topics down in detail.
The C-10 trade exam: your home turf
The trade exam is the one built on the C-10 blueprint and the 2025 California Electrical Code. It leans on the fundamentals you use in the field, tested as calculations you have to do without the book in front of you: dwelling load calculations, conductor ampacity and wire sizing, overcurrent protection, and grounding and bonding. For the full topic weighting, see what is on the C-10 electrical exam.
This is your strength if you have real field experience — but experience alone does not carry it. The exam rewards speed and precision on calculations most electricians have not done by hand since their apprenticeship. Timed practice is what closes that gap.
Key differences at a glance
- Content: Law and Business is business and legal; the trade exam is technical and code-based.
- Reuse: the Law and Business exam is shared across all classifications; the trade exam is C-10 only.
- Familiarity: field electricians know the trade material and often underestimate the law.
- Scheduling: you can take them on different days. If you fail one, you re-sit only that one. See the exam format and passing score for the mechanics.
How to prepare for both without wasting time
The mistake is spending most of your study time on the trade exam because it feels productive, then walking into the Law and Business exam cold. Split your prep deliberately:
- Trade exam: drill calculations under a clock until the load calcs and ampacity lookups are automatic. Reps build the speed the exam demands.
- Law and Business exam: treat it as new material to learn, not review. Study the lien deadlines, contract rules, and employment law the same way you would study code you had never seen.
A good prep course covers both exams — trade and law — so you are not stitching together a trade study guide and a separate business book. Working full practice questions for each, until both feel routine, is how you pass on the first attempt instead of paying to re-sit the one you neglected.
The bottom line
Two exams, one license, and you control both. The trade exam is where your experience shows; the Law and Business exam is where your discipline shows. Prepare for the one you know less about with the same seriousness as the one you know cold, and you walk out licensed.