What material is type letter THHN primarily made of?

Type THHN wire is primarily made of copper, which is known for its excellent conductivity and is widely used in electrical applications. The wire is insulated with a coating of polyvinyl chloride (PVC), which protects against environmental factors and provides electrical insulation. However, the primary conductive material, which is crucial for understanding the wire's performance in electrical circuits, is copper.

While polyvinyl chloride is indeed part of the wire's structure, it is not the main material that defines the type THHN wire's functionality, which revolves around its ability to conduct electricity efficiently. Thus, it is essential to recognize that the primary component is the conductive material rather than the insulation.