Defines core electrical terms used throughout the NEC: accessible, ampacity, branch circuit, conductor, conduit, dwelling unit, raceway, service, and more.

General installation requirements: working clearances in front of electrical equipment, headroom in electrical rooms, illumination, dedicated space above panels, and examination/approval of equipment.

Rules for branch circuits: minimum sizes, AFCI/GFCI requirements by location, small appliance circuits in kitchens, 20A receptacle circuits, and laundry circuits.

Load calculation methods for sizing service entrances and feeders, including standard and optional calculation methods for dwelling units.

Overcurrent protection rules: breaker and fuse sizing, locations where overcurrent protection is required, and conductor protection.

Complete requirements for system grounding, equipment grounding, bonding of metal parts, and grounding electrode systems.

General rules governing all wiring methods: protection from physical damage, securing and supporting cable and conduit, underground installation depths, and penetrations through fire-rated assemblies.

Conductor types, sizes, ampacity tables (Table 310.15(B)(16)), temperature ratings, and correction factors for ambient temperature and bundled conductors.

Box fill calculations, box depth and size requirements, support of boxes, and accessibility requirements.

Permitted uses, support and securing requirements, and protection rules for NM cable in residential wiring.

Switch installation requirements including height, location, type ratings, and AFCI requirements.

Requirements for receptacle installation: GFCI and AFCI protection, height requirements, outdoor receptacles, tamper-resistant receptacles in dwelling units.

Requirements for panelboard installation, labeling, circuit identification, and dedicated space.

Installation requirements for appliances including dishwashers, disposals, cooking equipment, electric water heaters, and HVAC equipment.

Motor circuit conductor sizing, overcurrent protection, controllers, and disconnects for motors and HVAC equipment.

Specific rules for air-conditioning and refrigeration equipment, including hermetic motor compressors.

Requirements for emergency electrical systems in buildings where failure of normal power could jeopardize human life.

Installation requirements for photovoltaic systems including inverters, dc circuits, rapid shutdown, and arc fault protection.

Installation of telephone, data, cable TV, and low-voltage communication wiring, including separation from power wiring and fire-stop requirements.

Structural design loads: live loads, dead loads, wind loads, snow loads, seismic categories, and soil bearing capacity requirements.

Egress requirements: stair width, riser/tread dimensions, handrails, landings, doors, and emergency escape openings (windows) from sleeping rooms.

Foundation footing requirements: minimum depth below frost line, minimum width, bearing capacity, and concrete strength.

Dimensional lumber floor joist sizing, span tables (Table R502.3.1), bearing requirements, notching and boring rules, and cantilever limits.

Prescriptive requirements for attached and freestanding decks: ledger connections, post sizes and heights, beam spans, and joist spans.

Wall stud sizes, heights, spacing, top plate requirements, header spans, corner framing, and balloon framing.

Weather-resistive barriers (WRB), flashing, lap siding installation, stucco, EIFS, and masonry veneer attachment requirements.

Rafter sizing and span tables, ridge board and ridge beam requirements, collar ties, rafter ties, ceiling joist spans, and hip and valley framing.

Minimum installation requirements for asphalt shingles, wood shakes, tile, metal roofing, and low-slope roofing materials.

Masonry chimney dimensions, height above roof, liner requirements, clearances to combustibles, and flashing.

Fire separation requirements between dwelling units, between garages and living spaces, and exterior wall construction near property lines.

Minimum natural light and ventilation requirements for habitable rooms, bathroom ventilation, and minimum heating standards.

Guard height requirements, opening limitations (no sphere greater than 4 in), and structural loading requirements.

Foundation requirements including soil investigation, frost protection, and design load criteria.

Crawl space ventilation, vapor retarder requirements, access opening size, and clearances to grade.

Window installation, impact resistance in high-wind zones, safety glazing locations, and garage door requirements.

Gypsum board installation requirements, nail/screw spacing, minimum thickness for walls and ceilings, corner bead, and water-resistant backing in wet areas.

Access requirements for mechanical equipment including furnaces, air handlers, and water heaters.

Fixture unit values for sizing cold and hot water supply piping. Assigns WSFU values to common fixtures (toilets, lavatories, showers, bathtubs, etc.).

Fixture unit values for sizing drain, waste, and vent (DWV) systems. Each fixture type is assigned a DFU value based on its discharge rate.

Maximum drainage fixture units allowed on horizontal drain pipe and vertical stacks at various pipe diameters and slopes.

Minimum slope requirements for gravity-flow horizontal drain pipes: 1/4 in per foot for pipes 2.5 in and smaller, 1/8 in per foot for 3 in and larger.

Sizing and requirements for main vent stacks through the roof, minimum stack diameter, and extension above the roof.

Permits and restrictions for air admittance valves (Studor vents) as alternatives to individual or branch vents.

Pipe size selection tables for cold and hot water supply based on water supply fixture units (WSFU) and pipe material.

Requirements for shutoff valves at service entrance, each fixture, water heaters, and other appliances.

Minimum hot water temperature requirements (120°F at fixtures), recirculation system requirements for long runs, and thermal expansion relief.

Backflow prevention requirements, air gaps, reduced pressure zone (RPZ) assemblies, and irrigation system backflow protection.

Requirements for grease interceptors (grease traps) in commercial food service, oil separators in automotive facilities, and sand interceptors.

Approved pipe and fitting materials for water supply, DWV, and gas systems by application type.

Natural gas and propane pipe sizing tables based on pipe diameter, run length, and BTU/hr demand (from the International Fuel Gas Code, which IPC references).