Which industrial cover/box combination violates the NEC®?

The National Electrical Code (NEC) provides guidelines on the appropriate sizes for electrical boxes and covers depending on their dimensions and the number of conductors, devices, or fixtures they accommodate.

In the case of the cover/box combinations listed, the correct answer is one that demonstrates an insufficient volume for the box's dimensions and intended use. A 4 x 1.5 square box typically accommodates a certain number of conductors and devices, and it has a specific volume needing to be met according to the NEC.

The 4 x 1.5 square box combined with a 5.0 in³ cover likely falls short of the required volume needed for safe installation, especially when considering the total number of conductors or devices. When the volume is inadequate for the intended electrical usage, it can lead to overheating, restricted air flow, and potentially hazardous conditions.

The other combinations either meet or exceed the volume requirements based on their respective dimensions and are therefore compliant with NEC guidelines. This is crucial for ensuring safe and efficient electrical installations that comply with code regulations.