What is the primary subject of Article 394?

Article 394 of the National Electrical Code (NEC) focuses specifically on "Concealed Knob-and-Tube Wiring." This type of wiring method was common in the early 20th century but has largely been phased out in modern electrical installations due to safety concerns. The article provides guidelines and requirements governing the use of this wiring method to ensure electrical safety.

The section covers various aspects, including installation practices and safety considerations that are essential for those working with older electrical systems. This is critical in managing safety hazards associated with aging wiring, which may not meet current standards due to deterioration and increased electrical demands of contemporary appliances.

In contrast, the other choices pertain to different subjects. Open Wiring on Insulators deals with wiring methods that are visible and may not be suitable for modern applications. Fixture Wires refer to the specific types of wires used to connect lighting fixtures but do not encompass general wiring practices. Switches are covered under different articles that focus more on devices for controlling electrical circuits rather than wiring methods specifically. Overall, Article 394 is distinctly about the rules and considerations for safely using knob-and-tube wiring, solidifying its position as the primary subject of this article.