C-10 Electrical Contractor License: Complete Exam Guide
The C-10 is California's electrical contractor classification. It covers wiring, lighting, power distribution, and electrical apparatus.
Exam blueprint
CSLB's 2026 C-10 outline weights:
- Planning and estimating — 18%
- Service and distribution — 22%
- Branch circuits and feeders — 20%
- Special systems (low voltage, fire alarm) — 14%
- Code compliance (NEC + Title 24) — 16%
- Safety — 10%
High-leverage study topics
- NEC Article 250 (grounding & bonding) — appears in ~12% of questions
- Voltage drop calculations
- Conduit fill and ampacity tables
- GFCI/AFCI requirements (heavily updated 2023 NEC)
- Title 24 lighting controls
Common mistakes
- Memorizing tables instead of understanding ampacity adjustments
- Skipping low-voltage / fire alarm questions (still ~14% of the exam)
- Ignoring California Title 24 amendments to the NEC
Study plan (6 weeks)
| Week | Focus |
|---|---|
| 1 | NEC fundamentals + diagnostic |
| 2 | Service & distribution |
| 3 | Branch circuits |
| 4 | Special systems + safety |
| 5 | Code review + Title 24 |
| 6 | Full-length practice exams |