What is the primary subject of Article 394?

The primary subject of Article 394 of the National Electrical Code (NEC) is indeed focused on the regulations and requirements surrounding conductor and cable assemblies that are used in specific applications. Within this context, Article 394 specifically addresses concealed knob-and-tube wiring, which involves the use of insulated conductors run through walls, ceilings, and other concealed spaces typically involving the use of knobs and tubes for physical support and protection.

This wiring method is significant in older electrical installations but is recognized with specific provisions due to safety considerations. Understanding Article 394 allows for proper compliance when dealing with these older systems and ensures that any modifications or installations meet current safety standards.

While the other topics mentioned—open wiring on insulators, fixture wires, and switches—also fall under different articles in the NEC, they do not encapsulate the primary content and intent of Article 394, which is specifically tailored to knob-and-tube wiring practices and guidelines.