How does the National Electrical Code (NEC) best define a structure?

The National Electrical Code (NEC) defines a structure fundamentally as a building or constructed entity. This definition encompasses various forms of construction, including residential homes, commercial properties, and industrial facilities. The emphasis on "building or constructed entity" reflects the NEC's focus on ensuring electrical installations are safe and effective in environments where people live and work.

Understanding this definition is crucial because the NEC provides regulations that specifically pertain to how electrical systems should be designed, installed, and maintained in these physical structures. Proper adherence to these codes helps prevent electrical hazards, ensuring safety for occupants.

In contrast, the other choices do not capture the essence of what a structure is according to the NEC. A type of equipment refers to tools or devices rather than buildings; a system of wiring pertains to the electrical components within a structure, not the structure itself; and a non-permanent installation indicates a temporary arrangement that doesn’t align with the NEC's focus on permanent constructions where compliance with safety standards is essential.