Code Reference & Box Fill
NEC article summaries and a quick box fill calculator. Always verify with the latest NEC and local amendments.
NEC Article Reference
Working clearances must be maintained around electrical equipment for safe access.
Equipment must be installed and used in accordance with listing or labeling instructions.
AFCI requirements for dwelling unit branch circuits, including bedrooms and other areas.
General receptacle outlet placement requirements, including spacing and wall-counter rules.
A 125V receptacle may be required within 25 ft of HVAC equipment.
GFCI requirements for dwelling units and other locations such as bathrooms, kitchens, garages, and outdoors.
All conductors of the same circuit, including grounding and bonding conductors, must be contained in the same raceway or cable.
Box fill calculations and volume requirements for conductors, devices, and clamps.
NM cable supports and protection from physical damage.
Replacement receptacles must be listed, tamper-resistant where required, and GFCI/AFCI protected where required.
Overcurrent protection must be provided in panelboards and meet listing and interrupting ratings.
Air conditioning and refrigeration equipment must comply with Article 440 and other applicable articles.
Box Fill Calculator
Each conductor counts as its volume; each device yoke counts as two conductor volumes; the largest ground wire counts as one volume; and internal clamps count as one volume.