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

The characteristics that define Class 1, Class 2, and Class 3 circuits, as specified in Article 725 of the National Electrical Code, relate specifically to the application and power limitations associated with these circuits. Class 1 circuits are typically used for remote control and signaling applications where higher voltage levels are acceptable. Class 2 and Class 3 circuits, on the other hand, are designed to operate at lower voltages and are primarily used for power-limited applications to ensure safety and reduce the risk of electrical shock.

Class 2 circuits are intended for low-power applications that require limited voltage and current to ensure that they are inherently safe for the user. Class 3 circuits are similar, but they are often used for control and signaling purposes, where even lower power levels can be utilized.

This classification is vital in the design and installation of electrical systems because it helps ensure that circuits are used safely and appropriately, reducing the risk of hazards. The correct answer captures the full scope of these circuits as they relate to their function in signaling and power limitation, aligning precisely with the definitions provided in the NEC.