What is the role of Signaling Line Circuits (SLCs) in a fire alarm system?

• A. SLCs connect initiating devices and notification devices to the FACP.
• B. SLCs regulate building HVAC.
• C. SLCs are wired networks for security cameras.
• D. SLCs are used to power lighting fixtures.

Answer: (D)

Signaling Line Circuits provide the communication path between the Fire Alarm Control Panel and the devices that respond to or report alarms. On most systems, the SLC carries signaling data, allows devices like smoke detectors, heat detectors, and pull stations to be connected and addressed, and lets the panel monitor their status and control notification appliances (horns, strobes) as needed. In short, the role of the SLC is to connect initiating devices and notification devices to the FACP so they can communicate signals and be supervised for faults. It is not about regulating HVAC, wiring security cameras, or powering lighting fixtures—the latter tasks involve separate systems or circuits.