Before calculating a load, sizing a feeder, or selecting a disconnect, the project team has to resolve a more basic question first: whether the installation is actually within the NEC's scope. Part 1 of this five-part Article 90 series works through NEC 90.1 and 90.2(A)(1) - the two provisions that resolve that question, and the ones most design teams assume they already know without having read them closely.
Plain-English Highlights
Section 90.1 establishes the framework for using, applying, arranging, and enforcing the NEC. It also addresses rule language - the difference between mandatory ("shall"), permissive ("shall be permitted"), and informational text - along with equipment examination, wiring planning, and units of measurement. It is the Code's operating manual, not just its scope statement. Section 90.2(A)(1) identifies the work covered by the Code, including the installation and removal of electrical conductors, equipment, and raceways; signaling and communications systems; and optical-fiber cables.
Covered installations include buildings, structures, mobile homes, recreational vehicles, and floating buildings; yards, parking areas, carnivals, and industrial substations; connections between premises wiring and the electricity supply; certain utility-used buildings outside generating plants, substations, and control centers; marina and boatyard shore-power systems, including leakage-current monitoring; and systems exporting vehicle power to premises wiring or allowing bidirectional current flow.
The detail most design teams miss: NEC scope does not stop at the exterior wall, the service equipment, or the limits of new construction. It follows the installation - site work, demolition, existing equipment being reused, and increasingly vehicle-to-building power - wherever that installation actually is.
Why It Matters
Scope gaps create design and responsibility gaps. Site power, demolition, utility interfaces, specialty systems, and vehicle-to-building power can all affect grounding, overcurrent protection, disconnecting means, equipment ratings, and available fault current - none of which can be sized correctly until the team agrees on what is actually being designed and who owns each piece of it. Unclear boundaries rarely surface as a design problem first. They surface as a permit
Scope Determination Framework
Applying 90.2(A)(1) correctly is a matter of working through the covered-installation categories systematically rather than assuming the answer. A practical sequence: 1. Identify every point where premises wiring connects to something outside the building envelope - the utility supply, a detached structure, site lighting, a marina or boatyard shore-power pedestal, or a vehicle capable of exporting power back to the building. 2.
For each connection point, confirm whether it is new work, existing work being reused, or work being demolished, since each carries different documentation and verification requirements. 3. Identify the utility's point of demarcation for every connection point - not just the main service, but any secondary utility interface (site lighting circuits fed from a utility-owned pole, a temporary service, a generator interconnection). 4.
Confirm whether any portion of the installation falls under a 90.2(A)(2) exclusion (ships, mining, railways, communications utilities, or electric utilities) before assuming NEC coverage - Part 2 of this series covers that boundary in detail. 5. Document the resulting scope determination on the drawings themselves, not only in a specification section or a meeting note, so it survives value engineering, permit revisions, and contractor substitutions.
Where To Show It
E-001: adopted code edition, project scope statement, design criteria, and AHJ amendments. Site and power plans: exterior equipment, site lighting, and distribution serving areas outside the building envelope. Demolition plans: equipment and conductors being removed, de-energized, or made safe, with clear identification of anything left energized and why. E-701: sources, service point, utility interface, and one-line distribution. Schedules: electrical characteristics, ratings, and assigned trade responsibility for every piece of equipment identified in the scope determination.
**Do** - Define the complete electrical scope early, in writing, on the drawings - not only in the specifications. - Identify every utility and premises-wiring boundary explicitly, including secondary interfaces beyond the main service. - Include demolition, site work, and specialty systems (marina/boatyard shore power, vehicle-to-premises power export) in the scope determination, not just new construction. - Coordinate power requirements with MEP equipment early enough that voltage, phase, and available fault current are known before equipment is finalized.
**Do Not** - Assume the NEC applies only inside the building envelope. - Treat "existing to remain" as a verified condition rather than a claim that still needs to be checked. - Use "by utility" on a drawing without defining exactly where the utility's responsibility ends and the premises wiring begins. - Leave a vehicle-to-premises power export system, a marina shore-power connection, or a temporary service undocumented because it does not resemble a traditional branch circuit or feeder.
Common Review Risk
The most frequent scope-related permit
Drawing / Submittal Check
Before a set goes out for permit, confirm: (1) every utility and premises-wiring boundary identified in the scope determination appears on a drawing, not only in a specification section; (2) demolition scope explicitly states what is removed, what is de-energized, and what remains energized and why; (3) any marina, boatyard, or vehicle-to-premises power export system is shown with its own one-line and equipment schedule entry rather than folded into a generic power plan note; (4) the adopted NEC edition and any AHJ amendments affecting scope are stated on E-001, not assumed.
When To Escalate
Escalate a scope determination - to the full design team, the AHJ, or a pre-application meeting - when a connection point does not clearly fit any of the 90.2(A)(1) categories, when a project includes a specialty installation this series has not yet reached (bidirectional vehicle power export, marina shore power with leakage-current monitoring, or a utility-owned structure on private property), or when an existing condition cannot be verified without opening walls or ceilings that are outside the current scope of work.
Scope questions are cheap to resolve before permit submittal and expensive to resolve after a contractor has already priced the job.
Field Tip
Trace each electrical path from source to load, on paper, before the drawings are finalized. At every transition - utility to premises wiring, existing to new, energized to de-energized, fixed installation to vehicle-exportable power - identify ownership, protection, the disconnecting means, and exactly where that information is documented on the drawings. If any one of those four items is missing at a transition point, the scope determination is not complete yet, regardless of how finished the rest of the set looks.
Masterbuild QA Lens
Most NEC scope disputes at the MEP boundary trace back to a 90.2(A)(1) question that was never resolved before design started: is this installation within NEC scope, and where does the utility's responsibility end. Confirming scope first - before site work, demolition, and specialty systems are drawn - keeps grounding, overcurrent protection, and fault-current questions from surfacing as late permit comments instead of early design decisions. Always verify the locally adopted NEC edition and applicable AHJ amendments before applying any post in this series to a real project.