Fittings and connectors shall be used only with specific wiring methods. What must they be?

Fittings and connectors must be specifically designed and listed for the wiring methods they are to be used with to ensure safety and compatibility in electrical installations. When a fitting or connector is "designed," it indicates that it was created with certain features that allow it to function safely and effectively within particular wiring methods. This includes aspects such as physical characteristics, insulation properties, and mechanical strength.

Being "listed" means that the fittings and connectors have been tested and certified by a recognized testing laboratory, confirming that they meet specific safety standards and performance criteria for the intended use. Therefore, using fittings and connectors that are both designed and listed for a specific wiring method guarantees compliance with electrical codes and enhances the overall safety and reliability of the electrical system.

In contrast, choices that reference just being "approved," "designed only," or "listed only" imply a limitation in meeting the comprehensive requirements necessary for safe installation. They do not encompass the full spectrum of criteria an electrical installation must adhere to for safety and effectiveness. Thus, the combination of being both designed and listed is essential for ensuring that fittings and connectors are appropriate for their designated applications.