Which conductor can be connected to a lug that is listed for CU only?

Which conductor can be connected to a lug that is listed for CU only?

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

Answer: (B)

Copper is the conductor that can be connected to a lug listed for CU only. When a lug is marked CU only, it means the terminal is designed specifically for copper conductors and may not be suitable for aluminum due to differences in oxidation behavior, expansion rates, and connection characteristics. Using copper ensures a reliable, tight termination and proper electrical performance. Aluminum cannot be used with a CU-only lug because it requires lugs rated for aluminum (AL) or dual CU/AL ratings to handle the differences in metallurgy and connection behavior. Steel isn’t used as a current-carrying conductor for these terminations.

Copper is the conductor that can be connected to a lug listed for CU only. When a lug is marked CU only, it means the terminal is designed specifically for copper conductors and may not be suitable for aluminum due to differences in oxidation behavior, expansion rates, and connection characteristics. Using copper ensures a reliable, tight termination and proper electrical performance.

Aluminum cannot be used with a CU-only lug because it requires lugs rated for aluminum (AL) or dual CU/AL ratings to handle the differences in metallurgy and connection behavior. Steel isn’t used as a current-carrying conductor for these terminations.