NEC Quick Reference
Key National Electrical Code® sections explained. Based on NEC 2023 (NFPA 70).
NEC 210 — Branch Circuits
Requirements for branch circuit conductors, outlets, and overcurrent protection. Governs general-purpose, small appliance, and individual branch circuits.
Classification — Branch circuits rated 15, 20, 30, 40, and 50 amperes.
Conductors shall have an ampacity ≥ maximum load served, and ≥ branch-circuit rating.
OCPD rating shall not be less than the non-continuous load plus 125% of the continuous load.
Dwelling unit receptacle outlet requirements — wall spacing, countertop, island, etc.
NEC 215 — Feeders
Feeder conductor sizing and overcurrent protection requirements.
Feeder conductor ampacity shall not be less than that determined by Article 220.
Feeder overcurrent protection shall comply with Part I of Article 240.
NEC 220 — Branch-Circuit, Feeder, and Service Load Calculations
Methods for calculating electrical loads — general lighting, appliance circuits, demand factors, and optional methods.
General lighting loads by occupancy — VA per square foot values (Table 220.12).
Feeder load = largest motor load × 125% + sum of all other loads.
Demand factors for general lighting (Table 220.42) applied to portion exceeding 3000 VA.
Optional calculation for dwelling unit — 100% of first 10 kVA + 40% of remainder.
NEC 240 — Overcurrent Protection
Requirements for overcurrent devices (fuses, breakers), their ratings, and conductor protection. This is the backbone of electrical safety.
Next standard size up rule — OCPD rating may be next higher standard rating for conductors 800A or less.
Small conductor protection: #14 = 15A, #12 = 20A, #10 = 30A maximum.
Standard ampere ratings: 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100...
Feeder tap rules — 10-foot, 25-foot, and unlimited length tap conductor provisions.
NEC 250 — Grounding and Bonding
Requirements for grounding of electrical systems and equipment, and bonding of electrically conductive materials.
Service equipment grounding — grounding electrode conductor connection at service.
Grounding electrodes — metal underground water pipe, concrete-encased electrode, ground ring, rod/pipe.
Grounding electrode conductor sizing (Table 250.66).
Equipment grounding conductor sizing based on OCPD rating (Table 250.122).
NEC 310 — Conductors for General Wiring
Conductor insulation types, ampacity tables, and application rules for building wiring.
Conductor types and insulation temperature ratings (60°C, 75°C, 90°C).
Ampacity table — 3 current-carrying conductors in raceway, cable, or direct buried.
Ambient temperature correction factors applied to Table 310.16 values.
Adjustment factors for more than 3 current-carrying conductors in raceway.
NEC 430 — Motors, Motor Circuits, and Controllers
Complete requirements for motor installations: FLC tables, conductor sizing, overload protection, OCPD, controllers, and disconnects.
Use tables 430.247–250 for full-load current, NOT motor nameplate.
Motor branch-circuit conductors shall have ampacity ≥ 125% of motor FLC.
Motor overload protection — maximum 125% of motor nameplate FLA (1.15 SF) or 115% (1.0 SF).
Motor short-circuit and ground-fault protection — maximum percentages by motor type.
Full-load current table for 3-phase AC motors (460V).
Disclaimer: This quick reference is provided for convenience and does not replace the full text of NFPA 70, National Electrical Code®. Always consult the most current edition for design and installation decisions. NEC® and National Electrical Code® are registered trademarks of the National Fire Protection Association (NFPA).