Daily-use code: box fill, conductor sizing, overcurrent protection, AFCI and GFCI, tamper-resistant receptacles, working clearance, grounding and bonding
In one paragraph
The eight code questions you answer on almost every residential job, with the section numbers and the numbers themselves: how many conductors fit in a box (314.16), what wire a breaker allows and what ampacity a service needs (240.4(D), 310.16, 310.12), where AFCI and GFCI protection is required in a dwelling (210.12, 210.8), which receptacles must be tamper-resistant (406.12), how much clear space a panel needs and where it may not go (110.26, 240.24), and how the grounding electrode system and the bonding are built and sized (Article 250). Written from the 2025 California Electrical Code, which is the 2023 NEC with California amendments, in force since January 1, 2026. Paraphrased, with the section to read beside each rule.
The rule
The 2025 California Electrical Code adopts the 2023 NEC with California amendments, effective January 1, 2026 (Title 24, Part 3). The rules a residential electrician applies daily are: box volume per conductor size and the counting rules of 314.16; the small-conductor breaker limits of 240.4(D) and the 75-degree ampacity column of 310.16 with the 83 percent dwelling service rule of 310.12; the dwelling AFCI locations of 210.12(B) and GFCI locations of 210.8(A); tamper-resistant receptacles throughout dwelling units under 406.12; 3 feet deep, 30 inches wide and 6.5 feet high of working space at equipment under 110.26(A); and a grounding electrode system built and bonded under Article 250 with the grounding electrode conductor sized from 250.66.
Why it matters
These eight questions are the difference between a rough inspection that passes and one that costs you a day and a reinspection fee, and they are the same questions a homeowner's inspector will ask about your work when the house sells. Knowing the number and the section, without looking, is what lets you quote at the kitchen table and stand behind it.