Class 2 and Class 3 circuits are regulated under which NEC section?

• A. NEC 725
• B. NEC 500
• C. NEC 300
• D. NEC 400

Answer: (A)

Low-voltage, energy-limited circuits used in most alarm systems are regulated by NEC section 725. This article is dedicated to Class 2 and Class 3 circuits, defining their energy limits and the specific safety and wiring requirements that apply to them. The reason this is the right section is that alarm system wiring typically operates at low power and is designed to be inherently safer, which is exactly what Class 2 and Class 3 classifications address.

Other NEC sections cover different topics: general wiring methods are in the section that governs most electrical installation practices, flexible cords have their own section, and hazardous locations are addressed in a section focused on locations with special risks. Since alarm system circuits fall under energy-limited, low-voltage categories, NEC 725 is the appropriate reference.