When the Code refers only to a conductor size without specifying material, which material is intended?

When the code refers to conductor size without specifying the material, it is understood to imply copper. This is a widely accepted standard in electrical engineering and industry practices. Copper is favored for its excellent electrical conductivity, durability, and resistance to corrosion, making it the default material in many specifications and guidelines.

While aluminum is also a common conductor material, it is distinct from copper in terms of size and performance characteristics, often requiring larger conductor sizes to achieve similar conductivity levels. Steel and silver are less frequently referenced for general wiring purposes, with steel primarily used as a structural support or conduit material and silver being more costly and used in specialized applications due to its superior conductivity but impractical for standard wiring. Therefore, when no material is specified, referencing copper aligns with industry norms and standards.