Wire connectors labeled with only the wire size should ONLY be used with what type of conductors?

• A. Copper
• B. Aluminum
• C. Steel
• D. Plastic

Answer: (A)

Connectors labeled only with a wire size are intended for copper conductors. The internal clamp and sizing are designed around copper’s properties—its ductility, oxidation behavior, and how it crimps to form a reliable electrical and mechanical connection at the specified torque. Using those same connectors with aluminum can lead to poor contact and loosening due to differences in expansion, contraction, and corrosion, so special AL/Cu or all-aluminum connectors are required for aluminum conductors. Steel isn’t used as a typical residential conductor, and plastic isn’t a conductor, so they wouldn’t be appropriate here. Copper is the suitable conductor type for these labeling conventions.