What is a Class B circuit in fire alarm wiring?

What is a Class B circuit in fire alarm wiring?

• A. A loop that returns to the panel with redundancy.
• B. A star topology.
• C. A single continuous loop that ends at the control panel; a fault may disable devices along that loop.
• D. A wireless circuit.

Answer: (C)

In fire alarm wiring, Class B uses a single continuous circuit that runs from the control panel and ends back at the panel, without a redundant return path. Because there’s only one path for current, a fault anywhere along that run can disable devices beyond the fault since there’s no second route to bypass it. This is why a fault may affect multiple devices on the loop. Compared to Class A, which uses a looped path that provides redundancy, Class B is simpler and cheaper but less fault-tolerant. Wireless circuits and a star-style hardwired layout don’t describe Class B behavior, which is rooted in that single, non-redundant path.

In fire alarm wiring, Class B uses a single continuous circuit that runs from the control panel and ends back at the panel, without a redundant return path. Because there’s only one path for current, a fault anywhere along that run can disable devices beyond the fault since there’s no second route to bypass it. This is why a fault may affect multiple devices on the loop. Compared to Class A, which uses a looped path that provides redundancy, Class B is simpler and cheaper but less fault-tolerant. Wireless circuits and a star-style hardwired layout don’t describe Class B behavior, which is rooted in that single, non-redundant path.