What characteristics define Class 1, Class 2, and Class 3 circuits as specified in Article 725?

The classification of circuits as Class 1, Class 2, and Class 3 according to Article 725 of the National Electrical Code (NEC) is based on their intended use, voltage, and the level of power they can handle. These classifications specifically pertain to remote-control, signaling, and power-limited circuits, which encompasses a wide variety of applications such as fire alarm systems, security systems, and low-voltage control circuits.

Class 1 circuits are defined as those that operate at higher voltages and are typically used for control and non-power limited applications. Class 2 circuits are designed to operate at lower power levels and include the low-voltage signaling used in various types of communication devices and alarms. Class 3 circuits are similar to Class 2 but typically operate at slightly lower voltages, making them very safe for low voltage applications where the risk of electric shock is minimized.

Thus, the correct characterization relates directly to their differences in operation and safety features, aligning with the descriptive purpose of remote-control and signaling functions. This classification is essential for ensuring the proper installation and protection of electrical systems in compliance with safety standards, which is why A is the correct answer. The other options do not encompass the full range of applications and safety