C-10 vs C-7 vs C-45: Which California Electrical License Do You Need?
Most people searching for a California electrical contractor license land on the C-10 and never look further. That is usually correct, but not always. California licenses contractors by classification, and there are three that touch electrical work directly plus one general classification that keeps showing up in the confusion.
Here is how they actually differ, and how to figure out which one belongs on your application.
The short version
- C-10 Electrical — the broad electrical classification. Power wiring, distribution, devices, equipment. This is the default for an electrical contracting business.
- C-7 Low Voltage Systems — communication and signal systems. Data, telephone, sound, intercom, some alarm and control work.
- C-45 Sign — electrical signs: the sign itself, its supports, and the electrical work that feeds it.
- B General Building — not an electrical classification at all, but it comes up constantly because generals run projects that include electrical work.
Scope comparison
| C-10 Electrical | C-7 Low Voltage Systems | C-45 Sign | |
|---|---|---|---|
| Core focus | Electrical systems generally: generation, transmission, distribution, utilization | Communication, signal, and low-energy systems | Electrical signs and their supporting structures |
| Typical work | Service upgrades, panels, branch circuits, feeders, lighting, motor circuits, EV charging, commercial and industrial power | Structured cabling, telephone and data, sound and intercom, certain alarm and control systems | Channel letters, pylon and monument signs, illuminated cabinets, sign supply circuits and disconnects |
| Trade exam content | Broad NEC-based electrical: load calcs, ampacity, overcurrent, grounding and bonding, boxes and raceways, motors and transformers | Low voltage and communication systems focus | Sign fabrication, erection, and the electrical work supplying signs |
| Who it fits | Anyone selling electrical work as their business | A company that only does comm and signal work and does not want the full electrical exam | A sign shop that builds, installs, and services signs |
| Law and Business exam | Required | Required | Required |
| Four-year experience requirement | Required | Required | Required |
All three specialty classifications sit on the same foundation: journey-level or higher experience in the classification you are applying for, the Law and Business exam, the trade exam, a contractor bond, and a workers compensation policy if you have employees. Read the full C-10 requirements for how that experience is documented and certified.
When the C-10 is obviously the answer
If you are wiring services, pulling feeders, setting panels, running branch circuits, installing lighting, terminating motor circuits, or doing EV charger installs, you want the C-10. It is written broadly enough to cover the electrical systems side of a normal electrical contracting business, and it is the classification building departments and general contractors expect to see on an electrical sub.
The trade exam reflects that breadth. Expect real calculation work — load calculations, conductor ampacity and sizing, overcurrent protection, and grounding and bonding all carry weight. Trade content is governed by the 2025 California Electrical Code, which adopts the 2023 NEC with California amendments, so study from the California edition rather than a plain NEC.
When the C-7 makes more sense
The C-7 exists for companies whose entire business is low-energy signal work. If you install structured cabling, phone and data systems, sound and intercom, nurse call, or similar communication systems — and you have no intention of touching general power wiring — the C-7 is a shorter path to a license that matches what you sell.
The trap is growth. Plenty of low voltage companies eventually get asked to add a circuit, move a panel, or provide power to the equipment they just installed. At that point you either sub it out to a C-10 or you go get the C-10 yourself. If you can already see that coming, sitting for the broader exam once is usually cheaper than doing it twice.
One thing that trips people up: contractor licensing and electrician certification are two separate systems in California. The CSLB licenses the business; the Division of Labor Standards Enforcement certifies individual electricians who work for C-10 contractors. That distinction is worth understanding before you plan a career path — see contractor license vs electrician certification.
When the C-45 is the right call
The C-45 Sign classification is genuinely specialized. Sign work is a package deal: the cabinet or channel letters, the structural support and mounting, and the electrical supply, disconnect, and internal wiring. A shop that fabricates and erects signs is doing structural and electrical work at the same time, and the C-45 is scoped for exactly that combination.
If signs are your business, the C-45 is the efficient license. If signs are one line item inside a broader electrical company, the C-10 is likely the better fit — but confirm the current scope language with the CSLB rather than relying on a summary, including this one.
Where the B general contractor fits
The B General Building classification covers projects that require at least two unrelated building trades — the classic ground-up or full-remodel job. A B typically subcontracts the electrical scope to a licensed electrical contractor.
What the B does not do is act as a workaround. A general contractor cannot simply decide to take standalone electrical jobs because they hold a B. If electrical work is what you are selling, the electrical classification is what you need. The line between "project involving multiple trades" and "electrical job" is exactly the kind of thing CSLB enforcement looks at, so if you are near it, ask before you bid. Our overview of when a license is required for electrical work walks through the practical boundaries.
Can you hold more than one?
Yes. Contractors add classifications to an existing license routinely — a C-10 holder who starts doing significant sign volume can pursue the C-45, and vice versa. Each added classification generally requires its own trade exam and its own qualifying experience, though the Law and Business exam is not something you retake for every classification once you have passed it. Application fees, renewal timing, and exam scheduling change from time to time, so verify the current numbers and process on cslb.ca.gov before you budget.
How to decide
Ask one question: what will you put on a customer invoice?
- Electrical systems and power work → C-10
- Communication and signal systems only → C-7
- Signs, start to finish → C-45
- Multi-trade construction projects where electrical is a sub → B, with a licensed electrical sub
If the honest answer is "mostly one, sometimes the other," lean toward the broader classification and sub out the edges. It is easier to narrow your work than to turn down a job you are not licensed for.
Then comes the exam
Whichever classification you pick, the licensing path ends the same way: two exams, both of which people underestimate. The Law and Business exam catches contractors who assume years in the field will carry them, and the trade exam rewards people who have done the calculations under time pressure rather than just read about them.
The single most reliable predictor of passing is not how many hours you studied — it is whether you have worked enough timed practice questions to know your pace and to recognize where you are still guessing. Build that habit early, and exam day stops being a mystery. If you want a structured start, our C-10 study guide lays out a workable sequence.