Purpose
Article 100 of the National Electrical Code® (NEC®) provides clear definitions for terms used throughout the Code.
Understanding these definitions is essential because NEC requirements depend on how each term is officially defined — not just what it sounds like in everyday language.
Key Concepts
- The NEC uses precise definitions to avoid misinterpretation during design, installation, and inspection.
- When a word or phrase is defined in Article 100, that definition must be used consistently across all code articles.
- Misunderstanding a definition can lead to code violations or unsafe installations.
How the Terms Are Organized
Article 100 divides terms into two sections:
- General Definitions – Common terms used throughout the NEC.
- Part-Specific Definitions – Terms related to particular articles or systems (e.g., hazardous locations, communication circuits, renewable energy systems).
Examples of Common NEC Definitions
| Term | Definition (Simplified) |
|---|---|
| Accessible (as applied to equipment) | Equipment that can be reached without removing permanent barriers. |
| Bonding | The intentional electrical connection that ensures continuity and conductivity between metal parts. |
| Grounded (Grounding) | Connected to the earth or a conductive body that serves instead of the earth. |
| Overcurrent Device | A protective device (breaker or fuse) that automatically interrupts excessive current. |
| Panelboard | A panel that includes overcurrent devices and switches for controlling branch circuits. |
| Service Equipment | The equipment that connects the building’s wiring to the utility supply. |
| Voltage (Nominal) | A rounded value used to identify system voltage (e.g., 120V, 240V). |
| Qualified Person | Someone with the training and skills to recognize and avoid electrical hazards. |
Why It Matters
- Inspectors, designers, and electricians must interpret NEC language based on defined terms, not assumptions.
- Knowing where to find official definitions helps prevent disputes during inspection or enforcement.
⚙️ Key Takeaway
Article 100 is the dictionary of the NEC — mastering these definitions ensures consistent understanding, safer installations, and proper code compliance.
- Advertisement -
Disclaimer
This content is for informational purposes only and does not represent the official views of the NFPA or Voltage Lab. Always verify with the latest NEC edition and consult qualified professionals.
