| Publisher | NFPA |
|---|---|
| Type | Code (model installation code) |
| Scope | Requirements for the safe installation of electrical conductors, equipment, raceways, signaling and communications systems in public and private premises. |
| Who uses it | Electrical engineers, electricians, contractors, electrical inspectors, building officials, designers and facility owners across the United States. |
| Edition note | NFPA revises the NEC on a three-year cycle (for example, the 2020, 2023 and 2026 editions). The enforceable edition depends on what each state or local jurisdiction has adopted; refer to NFPA and the authority having jurisdiction. |
What It Is
NFPA 70, the National Electrical Code, is the most widely adopted electrical installation code in the United States. It is written by NFPA code-making panels made up of manufacturers, installers, inspectors, insurers, engineers and other interests, and its purpose is the practical safeguarding of persons and property from hazards arising from the use of electricity. It is not a design manual or an instruction guide for untrained persons; it sets minimum requirements.
The code is organized into an introduction (Article 90), nine chapters and informative annexes. Chapters 1 through 4 apply generally: definitions and general requirements, wiring and protection (including branch circuits, services, overcurrent protection and grounding and bonding in Article 250), wiring methods and materials, and equipment for general use. Chapters 5, 6 and 7 cover special occupancies, special equipment and special conditions and may modify the general rules. Chapter 8 covers communications systems, and Chapter 9 contains tables such as conduit fill and conductor properties.
Why It Matters
The NEC is a model code. It becomes law when a state, county or city adopts it, often with local amendments, and it is then enforced through permits and inspections by the authority having jurisdiction. Because adoption dates differ, two jurisdictions may enforce different editions at the same time, which affects design and installation decisions.
Compliance has practical consequences beyond inspection approval. Insurers, owners and courts look to the NEC as the benchmark of safe installation, OSHA's general industry electrical design rules are closely based on it, and product listing and labeling practices are built around its requirements.
Key Concepts
- Authority having jurisdiction (AHJ) — the organization, office or individual responsible for enforcing the code and approving equipment, installations and procedures.
- Listed and labeled equipment — equipment evaluated by a qualified testing organization and identified as suitable for a specific purpose, a central basis for AHJ approval.
- Grounding and bonding — Article 250 rules that establish an effective ground-fault current path and limit voltage on conductive parts so protective devices operate.
- Overcurrent protection — requirements for fuses and circuit breakers to protect conductors and equipment from overloads, short circuits and ground faults.
- Wiring methods — permitted cable and raceway systems and the conditions under which each may be used, supported and protected.
- Working space — clear space requirements around electrical equipment that allow safe operation and maintenance.
- Special occupancies and equipment — later chapters adapt the general rules for situations such as hazardous locations, health care facilities, solar photovoltaic systems and emergency systems.
Who Should Know It
- Electrical engineers and designers preparing construction documents
- Electricians, foremen and electrical contractors
- Electrical inspectors and plan reviewers
- Facility engineers managing modifications and expansions
- Students preparing for licensing or certification examinations
Related Standards
- NFPA 70E — addresses safe work practices on installations built to the NEC.
- NEC Articles 500-506 — the hazardous location articles within the NEC.
- NFPA 72 — the fire alarm and signaling code that works with the NEC's fire alarm wiring rules.
- IEC 60364 — the international counterpart for low-voltage installations used outside North America.
How ASEEE Uses It
ASEEE electrical installation programs map learning outcomes and assessments to NEC concepts such as grounding and bonding, overcurrent protection, wiring methods and working space, emphasizing the reasoning behind requirements. See related ASEEE programs.
ASEEE Programs Referencing This Standard
- Electrical Installations Level 1
- Electrical Installations Level 2
- Electrical QA/QC Inspector
- Fire & Gas Detection and Alarm Systems (FGDS)
- Modern Power System Protective Relaying
- NFPA Fire Protection Specialist
- Substation Design: Main Equipment
Educational summary only. ASEEE is not the publisher of this document and this page does not reproduce or replace it. Always consult the current official edition from NFPA for requirements.