/ Field knowledge · NEC 90.7–90.9 · Sparky Edition
The listing is for the equipment as evaluated.
NEC 90.7–90.9: the listing is for the equipment as evaluated. A field-cut enclosure is a different product. Factory internal wiring generally is not re-inspected — unless it was altered or damaged.
Educational 2026 NEC 90.7, 90.8, and 90.9. Confirm the adopted edition. Distinct from approved / listed / labeled / identified and 90.2(C) adequacy. This is not a spare-capacity calculation.
- 90.7 Examination of equipment for safety: product evaluation, testing, inspection, and safety standards are a basis for approval. Factory-installed internal wiring generally does not require reinspection at installation, except where altered or damaged, when evaluated by a qualified electrical testing laboratory as addressed by the Code. Verify listing, recognition, and suitability. Respect the conditions of evaluation. Reevaluate field modifications that may affect approval.
- 90.8 Wiring planning: consider adequate raceway space, spare raceways, space for future electrical and communications circuits, and distribution equipment positioned for practical future additions. This is not permission to oversize everything. Future provisions should reflect reasonable project needs.
- 90.9 Units of measurement: SI is preferred, then inch-pound. Hard conversion changes the actual measurement; soft conversion may change only the description. Trade sizes follow recognized industry designations. Soft conversion cannot be used where safety would be affected.
Listed last year, cut last week
An added accessory, an altered enclosure, a relocated component — with no reevaluation — looks approved because it once was, not because it currently is. Do not mix measurement systems on safety-related dimensions. Do not confuse reasonable future planning with arbitrary oversizing.
Source: Sparky 90.7–90.9 · listed: listed vs labeled · arrangement: 90.3–90.6.
What to send
The nameplate photo (safe access), what was field-modified, and the listing basis on the schedule.
If the enclosure was cut after listing
Send the photo. Masterbuild will say whether 90.7 even still has a listing basis — or the equipment as installed is not the equipment as evaluated.
Send Project Background+1 (786) 398-6940 · osmany.portal@masterbuildconsulting.com
Masterbuild provides engineering services under a written scope. Nothing on this page is project-specific engineering advice, a code interpretation for your project, or a representation about permit approval. Confirm the adopted edition. Distances below are 2024 IMC / 2026 NEC model-code education from Daily Code Talk.