How does a Class B circuit differ from a Class A circuit?

A Class B circuit is characterized by its wiring configuration, which does not include a redundant path. In a Class B circuit, devices are connected in a "loop" where the circuit terminates at both ends, but if the circuit were to be broken at any point, all devices located beyond that break would cease to function.

This design means that the failure of any single point in the circuit can result in a portion of the system becoming inoperative. Therefore, the absence of a redundant path is significant, as it ensures that a fault will disrupt the entire section of the circuit rather than enabling the system to continue functioning through an alternate route, which is a defining feature of Class A circuits.

Understanding the distinction between Class A and Class B circuits is essential, particularly in fire alarm systems, where system integrity and reliability are critical for safety. A Class A circuit’s redundancy allows it to maintain functionality even if one section becomes compromised, contrasting sharply with Class B's reliance on a single path for signal transmission.