Before applying a Code requirement, the project team has to understand what its terms actually mean. Article 100 is not a dictionary exercise; it is where words that sound interchangeable can establish different electrical concepts, responsibilities, and review outcomes.
Technical Basis and Scope
This is NEC Article 100 terminology education based on the owner-supplied NEC 2026 source. It is not a project-specific code determination. Confirm the locally adopted NEC edition, amendments, AHJ interpretation, equipment listing, and actual installation before using it on a permit set or in the field.
Series Focus
This series groups foundational Article 100 terminology around how electrical systems are actually designed, reviewed, coordinated, built, inspected, and maintained. The focus is equipment approval and suitability; distribution terminology; services, feeders, and branch circuits; grounding and bonding; fault current and protection; voltage and load terminology; and equipment access and location conditions.
Why It Matters
A terminology error can become a design error when it reaches the one-line, panel schedule, equipment schedule, specification, submittal, field note, or inspection response. Approved is not the same as listed; accessible is not the same as readily accessible; a feeder is not a branch circuit; an outlet is not automatically a receptacle.
Where It Shows Up
One-lines and risers; panel and equipment schedules; service and feeder design; grounding and bonding diagrams; fault-current and equipment-selection studies; HVAC and motor coordination; existing-building investigations; permit review; and inspection records.
How To Use This Series
Read each term as a decision tool. Ask what it requires the drawings to identify, what a submittal must prove, what condition the field team must verify, what evidence must be retained, and whether the adopted code or AHJ has a project-specific requirement beyond the model-code concept.
Do / Do Not
Do use the NEC term that matches the actual condition. - Do verify adoption, amendments, AHJ interpretation, product listing, and manufacturer instructions before project use. - Do not substitute familiar trade language for a defined term when the requirement turns on that distinction. - Do not use a broad code-education article as a project-specific design decision.
Field Tip
When a word appears in a review comment, do not answer from memory. Locate the definition, then locate the operative requirement that uses it. The definition frames the word; the applicable project requirement determines the decision.
Masterbuild QA Lens
Definitions are most valuable when they make the permit proof chain clearer: condition, applicable requirement, drawing location, product or field evidence, responsible reviewer, and closeout record.