Wire connectors marked only with the wire size should be used on what type of conductors?

Wire connectors that are marked only with the wire size are specifically designed for use with copper conductors. This is because they have been tested and rated to ensure reliable connections and performance with copper wiring, which has different characteristics compared to aluminum or other metals.

Copper has better conductivity and lower resistance, which can affect the choice of connectors used. The materials and construction of connectors designed for copper ensure compatibility with the physical and electrical properties of copper conductors.

Connectors, in contrast, intended for aluminum conductors often need to accommodate the different expansion rates and conductivity characteristics of aluminum. When a connector is marked solely with wire size, it indicates it has been evaluated under standards that pertain exclusively to copper, emphasizing safety and effectiveness in connections made with that specific type of conductor.

Multi-stranded conductors, while they can use connectors marked with wire sizes, also have types of connectors specifically designed for them, so the generalization that is only for copper conductors is more precise in this context.