A listing mark is not a blank check. Article 100 separates four questions that need to be answered before a product lands on a schedule, submittal, or existing-condition assessment: who accepts it, what evaluation supports it, what mark is present, and whether it fits this actual use.
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.
Plain-English Control
Approved concerns acceptability to the AHJ. Listed concerns inclusion in a published list by an organization acceptable to the AHJ after evaluation for a stated purpose. Labeled concerns the label, symbol, or identifying mark carried by the product. Identified concerns suitability for the specific purpose, function, use, environment, or application required by the Code. They overlap, but they are not synonyms.
Field and Permit Impact
For an RTU disconnect, VFD, pump package, control panel, heater, or other utilization equipment, a review limited to 'is it listed?' can miss the real problem. Check the listing basis, required mark, environmental and application suitability, compatibility with the equipment served, and whether field modification changed the evaluated configuration.
Where To Show It
M/E schedules: exact equipment and electrical characteristics. Specifications and submittals: listing, labeling, and installation basis. General notes: required coordination and AHJ verification path. Existing-condition reports: recognizable marks, modifications, damage, and unresolved suitability evidence.
Review Path
Start with the exact product and intended use. Read the listing and manufacturer instructions, compare the actual voltage, location, enclosure, controls, and connected load, then document any item that needs manufacturer evidence, a field evaluation, or AHJ direction. Do not convert an unresolved product question into a generic note.
Do / Do Not
Do verify suitability for the actual application and environment. - Do review listing and labeling in submittals and at field observation. - Do not treat a product mark as proof it is suitable for every installation. - Do not assume a modified existing assembly remains acceptable without evidence.
Field Tip
If the original mark is missing, the enclosure has been altered, or the installation differs from the evaluated arrangement, preserve photographs and product data, identify the exact unknown, and route the decision to the responsible design professional, manufacturer, qualified evaluator, or AHJ as applicable.
Masterbuild QA Lens
The valuable deliverable is not a generic 'listed equipment' note. It is a traceable product-to-application record: what is installed or proposed, what proves its evaluated use, what the drawings require, and who must close any exception before release.