Frequently Asked Questions

The Signaling Line Circuit

• 1 Just What Is a Signaling Line Circuit (SLC)?
• 2 Are Addressable Fire Alarm Systems Different from Conventional Systems?
• 3 What is the Difference Between an Addressable System and a Conventional System?
• 4 What is the Difference Between Electricity Flow and Signal or Power Flow?
• 5 NFPA's 7 Classes of Fire Alarm Paths

Supervision & T-Taps on the SLC

• 6 What Is Addressable Supervision?
• 7 Is an EOL Resistor Needed for an Addressable System?
• 8 How many T-Taps are allowed on a Signaling Line Circuit (SLC)?

Programming and Addressing the Devices

• 9 How do You Use the Switches for Addressing?
• 10 Can a Control Module & Pull Station Address be Sequential?
• 11 It's the Volunteer Firefighter that Reads the Panel

Signals and Multiplexing

• 12 What are the Signals on the SLC?
• 13 Is the Signaling Line Circuit (SLC) a Data-Power Bus?
• 14 How Does Multiplexing of the Signaling Line Circuit Work?
• 15 How does an SLC Carry Both Signals and Power?

Modules and Devices

• 16 How Does the Panel Know the Address?
• 17 Why are Modules Needed in a Fire Alarm System?
• 18 What is Voltage Free Interfacing?
• 19 Can I use an Addressable Detector on a Conventional Panel?

Connecting Panels and Devices

• 20 Can an SLC Power a Horn or Strobe?
• 21 Can the Input and Output Wires on a Speaker be Reversed?

Troubles on the SLC

• 22 What Happens to the SLC when a Device is Disconnected?
• 23 Why Can't You Reset a Trouble on a Fire Alarm Panel?
• 24 Why Can't I Reset the Panel After Disconnecting the SLC?
• 25 Why Won't the Panel Show the Detectors?
• 26 How do I Fix a Damaged Loop?

Wire Length and Capacitive Lag

• 27 How does Capacitance and Shielding Affect Wiring?