Which NEC article covers Class 2 and Class 3 circuits used for security and fire alarm signaling?

• A. Article 400 (Flexible cords)
• B. Article 725 (Class 2 and 3 circuits)
• C. Article 110 (General safety)
• D. Article 520 (Theatrical)

Answer: (B)

Article 725 is the NEC section that covers Class 2 and Class 3 circuits used for signaling in security and fire alarm systems. These circuits are energy-limited by design to reduce shock and fire hazards, so they have a dedicated set of rules that govern conductors, installation methods, overcurrent protection, and listed power sources for signaling devices. This focused coverage is what makes it the right reference for security and fire alarm signaling circuits. The other articles mentioned address different topics—flexible cords, general safety, and theater lighting—and don’t apply to these low-energy signaling circuits.