Class 2 and Class 3 circuits used for signaling and control are covered by which NEC article?

• A. Article 450
• B. Article 517
• C. Article 725
• D. Article 800

Answer: (C)

Class 2 and Class 3 signaling and control circuits are power-limited circuits, meaning they are restricted in voltage and power to reduce shock and fire hazards in control and signaling applications. The NEC assigns these to Article 725, which defines what qualifies as Class 2 and Class 3, and lays out how they must be installed, including limits on voltage and power, wiring methods, and equipment requirements. This article ensures that devices like signaling, remote-control, and automation components operate safely with the restricted power they need.

Other articles cover different areas: motors and motor circuits are addressed separately, health care facility systems have their own provisions, and communications systems fall under another article. So for signaling and control circuits that are power-limited, Article 725 is the authoritative source.