What size wire requires a lug to fasten to an electrical device?

The correct answer, indicating that a size #8 wire and larger requires a lug to fasten to an electrical device, is based on the need for secure connections in electrical systems. Using a lug provides a robust mechanical and electrical connection which is critical for maintaining safety and performance in high-current applications.

When it comes to wire sizes, as the gauge number decreases, the diameter of the wire increases. A lug helps accommodate this increased diameter and ensures that the connection is tight and resistant to vibrations, which can come from normal operation or environmental conditions. This prevents overheating, potential arcs, and ensures continuous electrical integrity.

Wires smaller than #8 are typically flexible enough to be connected using standard terminals without the additional mechanical support that a lug would provide, making lugs unnecessary for those sizes. Thus, requiring a lug only for #8 wire and larger creates a balance between safety and practicality, enabling efficient energy transmission without compromising connection quality.