C-10 — Electrical

What Is a C-10 Electrical Contractor License?

A C-10 Electrical Contractor license is the CSLB classification that authorizes you to place, install, erect, or connect any wires, fixtures, appliances, apparatus, raceways, conduits, or solar photovoltaic cells that generate, transmit, transform, or utilize electrical energy for any purpose (CSLB Classification C-10; 16 CCR §832.10). In plain terms: it’s the license that lets you legally bid, contract, and pull permits for electrical work on homes, commercial buildings, and industrial sites in California — from a single panel upgrade to a full building rewire. CSLB folded solar photovoltaic installation directly into the C-10 scope, so a C-10 license also covers rooftop and ground-mount solar electrical work without a separate solar classification.

What a C-10 License Actually Covers

The classification is broad, but in practice C-10 work falls into a handful of recurring project types:

• Service and panel upgrades — replacing an aging 100-amp panel with a 200-amp service, including new grounding and bonding to current California Electrical Code (CEC) requirements.
• New construction rough-in and trim — running raceway and conductors through framing before drywall (rough wiring), then installing devices, fixtures, and covers after (finish wiring and trim).
• Solar PV and battery storage — installing rooftop or ground-mount photovoltaic arrays, inverters, and battery energy storage systems, including the interconnection wiring back to the main panel.
• Commercial tenant improvements — lighting retrofits, dedicated equipment circuits, and distribution panel work inside leased commercial space.
• EV charging circuits — dedicated 240V circuits and load calculations for Level 2 home and commercial EV chargers.
• Troubleshooting and repair — diagnosing nuisance breaker trips, failed GFCI/AFCI protection, or a dead circuit, and replacing the failed component.

C-10 Exam Breakdown

Every C-10 applicant sits for two separate exams: the Law and Business exam (required of all classifications) and the C-10 trade exam. Both are closed-book, computer-based, multiple-choice with four answer choices, and CSLB gives you a full 3.5 hours to complete each one (source: CSLB Examination FAQ). CSLB does not publicly publish the exact number of scored questions or the numeric passing score for the C-10 exam — test-prep providers commonly cite roughly 100–120 questions and a passing threshold in the high-60s to low-70s percent range, but treat those as industry estimates, not CSLB-confirmed figures.

What CSLB does publish is the official content outline in its C-10 License Examination Study Guide (current version, for exams scheduled June 1, 2024 and after), broken into five weighted sections:

• Planning and Estimating — 28% (existing system evaluation, plan/spec interpretation, electrical calculations, code requirements, material selection, solar/storage project planning)
• Rough Wiring — 27% (system layout, clearance/accessibility, raceway and panel installation, wire and equipment installation, grounding and bonding, solar/storage rough wiring)
• Finish Wiring and Trim — 11% (finish device placement, motor and equipment installation, wire/equipment labeling, trims and sealants, solar/storage finish wiring)
• Startup, Troubleshooting, and Maintenance — 16% (system energizing/testing, common electrical problems, locating and replacing inoperable wiring/components, test equipment selection, solar/storage system performance)
• Safety — 18% (lockout/tagout, PPE, tools/equipment, hazardous materials and job-site environments)

CSLB notes these percentages are approximate and that a calculator is provided for the math-based questions. Nearly half the exam (Planning and Estimating plus Rough Wiring) tests whether you can read a plan and correctly size, layout, and rough in a system before it’s ever energized — that’s where most first-time test-takers underprepare.

C-10 License Requirements

• Experience: At least 4 years of journey-level experience in electrical work within the last 10 years. Up to 3 of those years can be substituted with qualifying education (an apprenticeship completion certificate can offset up to 3 years; relevant bachelor’s degrees typically offset up to 2 years) — but at least 1 year must be hands-on practical experience.
• Application: File the Application for Original Contractor License (with Certification of Work Experience, form 13A-11) and pay the current $450 non-refundable application fee. Once your experience is approved, CSLB schedules you for the Law and Business exam and the C-10 trade exam.
• After passing: Pay the initial license fee ($200 for a sole owner, $350 for a partnership/corporation/LLC) and file your $25,000 contractor license bond (the bond amount set by SB 607, effective January 1, 2023).
• Workers’ compensation: You must have a Certificate of Workers’ Compensation Insurance or an Exemption from Workers’ Compensation Insurance on file at all times. C-10 is not one of the five classifications CSLB requires to always carry active coverage regardless of employees (that short list is C-8, C-20, C-22, C-39, and D-49) — so a C-10 licensee with no employees may file the exemption.

C-10 vs. Similar Classifications

C-10 vs. C-7 (Low Voltage Systems): C-7 covers energy-limited systems that don’t exceed 91 volts — phone systems, sound systems, cable/CCTV, satellite dishes, and low-voltage landscape lighting (fire and burglar alarm systems are excluded from C-7 entirely). If the work runs on standard 120/240V branch circuits or involves the main panel, that’s C-10, not C-7. Many electricians hold both so they can quote a job’s line-voltage rough-in (C-10) and its low-voltage cabling (C-7) under one contract.

C-10 vs. C-45 (Sign): C-45 covers fabricating, installing, and wiring electrical and non-electrical signs — channel letters, monument signs, illuminated cabinets. A C-45 contractor can wire the sign itself, but the C-10 is the classification for the building’s electrical service and circuits feeding that sign. Sign contractors doing only sign-specific electrical stay in C-45; anyone extending or modifying a building’s electrical system needs C-10.

C-10 vs. B (General Building): A B General Building contractor can only perform electrical work when it’s incidental and subordinate to an overall construction project involving at least two unrelated trades (16 CCR §831). A B contractor can’t legally take a standalone electrical job — a panel upgrade, a rewire, a solar install with no other trade attached — without a C-10 (or a properly licensed C-10 subcontractor).

Who Needs a C-10 License

Journeyman electricians going out on their own, solar installation crews (since C-10 absorbed solar PV scope), low-voltage or sign contractors who want to bring line-voltage work in-house, and general contractors who want to self-perform electrical instead of subcontracting it out all typically pursue C-10. Clients range from homeowners doing a panel upgrade or EV charger install, to property managers handling tenant-improvement electrical, to solar sales companies that need a licensed electrical arm to pull permits and sign off on installs.

C-10 Electrical FAQ

Does a C-10 license cover solar panel installation?
Yes. CSLB’s C-10 classification explicitly includes projects that generate, transmit, transform, or utilize electrical energy for any purpose, which covers rooftop and ground-mount solar PV and battery storage wiring. There is no separate CSLB solar classification.

Can I do low-voltage cabling work with just a C-10?
Yes — C-10 is broader than C-7 and legally covers low-voltage work too, but most electricians who regularly do standalone low-voltage jobs (no line-voltage scope) also carry a C-7 since it’s the classification specifically written for that trade.

How many questions are on the C-10 trade exam?
CSLB does not publish an exact figure. You’ll have up to 3.5 hours to complete it, and industry test-prep sources commonly estimate 100–120 questions — treat that as an estimate, not an official CSLB number.

What’s the passing score for the C-10 exam?
CSLB does not publish a fixed passing percentage for this exam. Your score report shows pass/fail, not the specific threshold used.

Can I substitute my apprenticeship for the 4-year experience requirement?
A completed apprenticeship certificate can offset up to 3 years of the 4-year requirement, but CSLB still requires at least 1 year of actual practical experience — you can’t substitute your way to zero hands-on time.

Do I need workers’ comp insurance to get a C-10 license?
You need either an active Certificate of Workers’ Compensation Insurance or a filed exemption on record with CSLB before your license issues. If you have no employees, you can file the exemption — C-10 is not one of the five classifications CSLB requires to always carry coverage.

Is the C-10 trade exam open-book?
No. Per CSLB’s official study guide, the C-10 trade exam is closed-book — no code books or reference materials are allowed in the exam room, though a calculator is provided for the math-based questions.

How much does a C-10 license cost overall?
Budget for the $450 CSLB application fee, the initial license fee ($200 sole owner / $350 for other entity types), and your $25,000 contractor bond (typically $145–$225/year in premium) — on top of whatever you spend preparing for the two exams.