NEC base (US)
WireSketch’s US region applies a baseline implementation of the National Electrical Code (NFPA 70). That label is honest, and it’s also a meaningful limit: vanilla NEC isn’t enforced anywhere in the United States. Here’s what that means in practice.
What the NEC is
The NEC is published by the National Fire Protection Association as NFPA 70. It’s a model code — a recommendation. It only becomes law when a state, county, or municipality adopts it, almost always with local amendments. The NEC is updated on a three-year cycle (2017, 2020, 2023, 2026...) and jurisdictions adopt different editions at different times. NFPA 70 (NEC) 2026 Edition is now published as the current edition, and is already accumulating formal Tentative Interim Amendments (TIAs) — meaning the model code itself is a moving target between cycles.
Why “vanilla NEC” isn’t a complete answer
The most consequential amendments WireSketch does not model:
- California — 2025 California Electrical Code (Title 24, Part 3): based on the 2023 NEC with California amendments. Published 1 July 2025, effective 1 January 2026. This is now in force statewide. Pattern matches California’s 3-year-lag, 6-month-delay adoption cycle (the 2022 CEC was based on 2020 NEC).
- California Title 24, Part 6 (Energy Code) — strict lighting controls, branch-circuit dedication rules for plug loads, and EV-ready infrastructure mandates for new construction. Materially affects every California residential project, beyond what Part 3 alone covers.
- NYC Electrical Code — New York City has its own substantial amendments to the NEC, particularly around service entrance, conduit fill, and cable types. Published as a co-document by NFPA (“NFPA 70 with NYC Amendments”).
- Chicago Electrical Code (Title 14E, Municipal Code) — one of the most amended versions in the US: mandates EMT conduit for most residential installations, where baseline NEC permits NM cable.
- Massachusetts (527 CMR 12.00) — Board of Fire Prevention Regulations adopts the NEC with state amendments.
- Many local AHJ-specific rules — e.g. utility service entrance methods, grounding-electrode requirements, conduit-fill specifics — vary by municipality.
What WireSketch’s NEC base does include
- 120 V single-phase load calculation for branch circuits (nominal US residential service)
- 15 A and 20 A branch-circuit conventions for general lighting and outlets
- NM-B (Romex) cable type with standard cross-sections (#14 AWG for 15 A, #12 AWG for 20 A)
- GFCI protection rules for wet locations (kitchens, bathrooms, garages, outdoors) per NEC Article 210.8
- Dedicated circuits for major appliances (range, dishwasher, refrigerator, microwave)
- EV charger circuits per NEC Article 625 baseline (240 V, dedicated, sized to charger continuous load × 125%)
- Bathroom 20 A dedicated circuit per NEC 210.11(C)(3)
- Standard switch height (~120 cm / 48″) and socket height (~40 cm / 16″)
What WireSketch’s NEC base does NOT include
- AFCI dwelling-unit branch-circuit rules (NEC 210.12) — the single biggest US residential rule of the last decade. AFCI protection is required for most 120 V branch circuits in dwelling-unit bedrooms, living rooms, dining rooms, hallways, kitchens, laundry, family rooms, and closets. WireSketch does not auto-flag missing AFCI on these circuits. On the roadmap; not today.
- NEC year selection — the app implements one baseline; you can’t pick “NEC 2020 vs 2023” to match your AHJ’s adopted edition.
- State and city amendments — CA Title 24, CEC, NYC, Chicago, MA, all listed above.
- Service-entrance and utility-specific rules — drop point, meter base, grounding electrode method.
- Conduit fill calculations — NEC Chapter 9 tables are not applied.
- Tamper-resistant receptacle (TRR) requirements — not flagged as a fixture-level rule.
- Calculated load (NEC Article 220) — total dwelling load with demand factors for service sizing is not computed; the app does per-circuit load only.
Bottom line for US users. Use WireSketch for planning conversations, fixture placement, and material rough-out. Do not treat its outputs as permit-ready or jurisdiction-compliant. The licensed electrician you hire will translate your layout into a design that complies with your local AHJ’s adopted NEC edition and amendments — that’s their job, and it’s the only path to a passable inspection.
Canada (CSA C22.1) is not the NEC
A common confusion: Canada uses the Canadian Electrical Code (CSA C22.1), not the NEC. The two share IEC influences but differ in voltage, cable type (NMD90 vs NM-B), AFCI / GFCI rules, and breaker conventions. If you’re in Toronto, Vancouver, or anywhere else in Canada, the US selector in WireSketch will give you wrong defaults. Canada is on the roadmap as a separate selector; for now, the app is sketching-only for Canadian projects.
Practical tip
For a US homeowner planning a kitchen remodel: capture fixture placement in WireSketch, generate the Renovation Brief PDF, and walk the licensed electrician through it. They’ll add AFCI breakers per NEC 210.12, apply your jurisdiction’s amendments, size the service per Article 220 calculated load, and produce a permit-ready design. The brief saves the “what do you want where” round-trip; it does not replace the design responsibility.
Important. WireSketch produces a planning and design artefact, not a compliance document. Standards are modelled at their baseline — local amendments apply, and final certification of any installation must come from a licensed electrician operating under your jurisdiction’s adopted edition and amendments.