What inscription on a wire connector indicates compatibility with both copper and aluminum wire?

The inscription that indicates compatibility with both copper and aluminum wire is typically "CU-AL." This designation signifies that the connector can be safely used with both types of wire materials, ensuring a good and reliable electrical connection without the risk of corrosion or other compatibility issues.

In electrical work, it is crucial to use connectors that match the type of wire being used, as using an incompatible connector can lead to poor connections, overheating, and potentially hazardous conditions. The marking "CU-AL" serves as a clear guideline for electricians to identify connectors designed for dual compatibility. Therefore, electricians can confidently use these connectors in mixed-metal applications without compromising safety or performance.

The other options do not clearly indicate compatibility with both materials. For example, "CU" only refers to copper, and "AL-CU" could imply a less standard configuration. "CU-AL FYI" suggests additional information or context but doesn't serve as an official compatibility designation. Hence, "CU-AL" is the appropriate label for connectors that accommodate both copper and aluminum wire.