What Does the NEC Mean by a Neat and Workmanlike Manner?
Section 110.12 says electrical equipment shall be installed in a neat and workmanlike manner. Three words, no definition, and an inspector who wants to write you up can lean on them hard. It is the single most subjective sentence in the Code, and knowing what backs it up is how you argue a call.
What the Code itself provides
Section 110.12 has three subsections that turn the general statement into something enforceable. 110.12(A) covers unused openings: openings in boxes, raceways, cabinets, and equipment enclosures must be effectively closed with fittings or plugs that provide protection substantially equivalent to the wall of the equipment. That is the missing knockout seal and the empty breaker space. 110.12(B) covers integrity of electrical equipment and connections: internal parts must not be damaged or contaminated by foreign material such as paint, plaster, cleaners, abrasives, or corrosive residues, and there must be no damaged parts that may adversely affect safe operation, including cracked or deteriorated insulation and parts damaged by corrosion, heating, or overheating. That is the painted panel interior and the burned lug. 110.12(C) in the 2023 Code addresses cables and conductors, requiring that they be installed in a neat and workmanlike manner and supported by the building structure so the cable or raceway is not damaged by normal building use.
The informational note under 110.12 points to accepted industry practices as described in ANSI/NECA 1, Standard for Good Workmanship in Electrical Construction, and other ANSI approved installation standards. NECA 1 is not adopted by reference and is not enforceable on its own, but it is the document an inspector will cite when asked to define the term, and it covers things like straight and level raceway runs, uniform support spacing, conductors dressed and trained inside enclosures, and equipment mounted plumb.
How to keep the conversation short
The realistic answer is that inspectors rarely write 110.12 by itself. They write it alongside a specific section because the specific section is what makes it stick. Loose cable in a panel gets 110.12 plus 314.17 or 312.5(C). Sagging Romex across a basement gets 110.12 plus 334.30. An unlabeled panel directory gets 110.12 plus 408.4(A). If you get cited under 110.12 alone with no supporting section, it is fair to ask which specific requirement the work fails, and a reasonable inspector will name one.
On the install side, four habits cover almost everything: seal every unused opening as you go rather than at the end, keep raceway runs parallel and perpendicular to building lines with consistent strap spacing, dress conductors in enclosures so they radius cleanly to their terminals with the free conductor length 300.14 requires, and mount equipment plumb and level. None of that costs meaningful time on a job that is already being built carefully, and it removes the discretionary part of the inspection entirely.