Best Cable Types for Addressable Fire Alarm Loops: FRLS vs Shielded Twisted Pair
Addressable fire alarm systems depend entirely on the reliability of communication loops. Every detector, module, and sounder communicates back to the Fire Alarm Control Panel (FACP) over a two-core cable. If the cable is not chosen correctly, it can lead to data loss, loop errors, false alarms or complete failure in emergencies. In India, two cable types are most commonly used in addressable fire alarm loops: This article compares both options in detail, from signal performance and attenuation tests to compliance with BIS/ISI standards, so you can confidently choose the right cable for your project. Why Cable Selection Matters in Addressable Fire Alarm Systems Conventional fire alarm systems only trigger signals, but addressable systems transmit digital data over communication loops. These loops carry: Any drop in signal quality can cause: So, selecting the correct core type, conductor size, insulation and shielding is critical. Cable Standards & Compliance in India Indian fire alarm cabling must comply with: Local AHJ (Authority Having Jurisdiction) may also demand ISI marking and CE compliance. What is FRLS Cable? FRLS (Flame Retardant Low Smoke) cables are widely used in fire detection systems across India. Features: Common Uses: What is Shielded Twisted Pair (STP) Cable? Shielded Twisted Pair is designed to reduce electromagnetic interference (EMI) and signal attenuation, which makes it ideal for digital data transmission used in addressable systems. Features: Common Uses: FRLS vs Shielded Twisted Pair – Feature Comparison Feature FRLS Cable Shielded Twisted Pair (STP) EMI Resistance Low High Smoke Emission Low Very Low (if FRLS-STP) Flame Spread Controlled Highly controlled Attenuation (over 1km) Higher Lower Use in Addressable Loops Limited Ideal Loop Stability Moderate Excellent Cost Low Slightly higher Compliance ISI/BIS BIS/UL/NBC compliant Accessibility in India High Moderate but growing Why Addressable Panels Prefer STP Addressable fire alarm systems transmit digital address signals that require clean communication without distortion. STP cables: Signal Attenuation Explained Signal attenuation refers to the loss of data strength as it travels along a cable. Factors that affect attenuation: Fire alarm loops often exceed 1 km, especially in hotels, malls, IT parks, airports and hospitals. At these distances, FRLS cables can cause data distortion. Signal Attenuation Tests – FRLS vs STP To compare both cables, a typical attenuation test setup involves: Test Parameters: Test Observation Table Parameter FRLS Shielded Twisted Pair Signal Loss @ 500m 4–6 dB 1–2 dB Signal Loss @ 1200m 8–12 dB 3–4 dB EMI Interference High Very Low Loop Fault Alerts Frequent Rare Device Drop-off Yes No False Alarms Possible Unlikely Interpretation: STP maintains cleaner signals over long loops, especially in electrically noisy environments. FRLS is adequate only for short runs below 300m with low EMI. Recommended Cable for Different Projects Small Buildings (< 10 devices per loop) Medium Commercial Projects Large Complexes / Malls / Airports Misconception: “FRLS is always enough” Many Indian installers use standard 1.5 sqmm FRLS cables even for addressable loops, but panel manufacturers like GST, Honeywell, Ravel and Siemens recommend: Improper cabling may pass initial testing but will fail during commissioning or event conditions. NBC and IS Standards Recommendation The National Building Code 2016 states that: “Cables for fire detection and alarm systems must ensure uninterrupted operation under fire and mechanical stress.” For addressable systems, additional shielding is now preferred, especially in: Cost Comparison (Per Meter – India Market) Cable Type Cost Range (₹/meter) FRLS 1.5 sqmm ₹25–₹35 STP FRLS 1.5 sqmm ₹40–₹60 Shielded Twisted Pair (UL Listed) ₹60–₹90 Note: Prices vary by brand, copper purity and ISI/UL certification. The difference of ₹15–₹20 per meter is justified when compared to: Installation Tips for Long-Term Reliability If you’re installing an addressable fire alarm system in India, follow this rule: For Loop Wiring: For Power & Sounder Circuits: Both FRLS and Shielded Twisted Pair cables are used in fire alarm wiring, but their suitability depends on the system type, EMI conditions and loop length. ✅ FRLS is fine for small, conventional, or short-range systems.✅ Shielded Twisted Pair (STP) is the best choice for addressable loops, especially in: With signal attenuation tests proving superior performance, STP ensures uninterrupted data transmission, regulatory compliance and life safety which is the ultimate goal of any fire protection system. Read Also: Top 10 Common Programming Mistakes Engineers Make in GST Addressable Panels Read Also: Can You Integrate GST Fire Alarm Panel with PLC / SCADA?
Can You Integrate GST Fire Alarm Panel with PLC / SCADA?
Industrial facilities today demand more than standalone safety systems. Engineers increasingly look for ways to integrate GST addressable fire alarm panels with PLC (Programmable Logic Controllers) and SCADA (Supervisory Control and Data Acquisition) platforms. The goal is clear: achieve centralized monitoring, automated plant responses and faster emergency handling. But is this integration possible?Yes – GST fire alarm panels can be integrated with PLC/SCADA systems, provided the correct communication protocols, hardware interfaces and programming logic are used. This detailed guide explains how the integration works, step-by-step, along with real-world methods, signal mapping, wiring options and best practices. Why Integrate GST Fire Alarm Panels with PLC and SCADA? Industrial plants with complex operations need interconnected safety, production and monitoring systems. Integration enables: Centralized Monitoring SCADA operators can view fire alarms directly from their HMI screens or control rooms. Automated Emergency Responses Your PLC can trigger shutdowns, ventilation systems, gas suppression or alarms based on fire panel signals. Real-Time Alerts Alerts can be logged, analyzed and shared with remote teams or BMS (Building Management Systems). Better Compliance Integrated reporting simplifies safety audits and insurance documentation. Reduced Human Error The system acts automatically without waiting for manual intervention. Common Integration Scenarios in Industries Here are real-use cases that automation engineers typically implement: Scenario Trigger from GST Panel PLC/SCADA Response Smoke detected Fire zone alarm Shut down AHU/fans automatically Heat sensor active Alarm relay output Stop conveyor belts or motors Manual call point Local activation Trigger hooters and SCADA pop-up Fault condition Fault relay Notify maintenance team Fire suppression Panel output Lock elevators, close fire dampers Available Interfaces on GST Fire Alarm Panels GST addressable panels (like GST-200, GST-100, GST-IFP8) offer multiple integration options: 1. Potential-Free Relay Outputs These dry contacts can be connected directly to PLC digital inputs. 2. RS-485 Communication (MODBUS / GST Protocol) Many panels support GST protocol over RS-485. Some models allow conversion to MODBUS RTU using interface modules. 3. Ethernet / TCP/IP (via gateways) A protocol converter or Bacnet/IP/Modbus TCP gateway can forward data to SCADA or BMS. 4. Signal Interfaces Integration Methods: Which One Should You Use? 1. Relay-Based Integration (Simplest & Widely Used) Best for basic automation requirements. How It Works: ✔ Pros: Fast, low-cost, no programming in panel✖ Cons: Limited to basic signal info Example Wiring: 2. RS-485 to MODBUS PLC Integration Used when detailed device-level communication is needed. Requirements: Benefits: 3. Integration Through Protocol Converters / Gateways Ideal when SCADA or BMS uses BACnet, OPC, or TCP/IP. Example Devices: These enable cloud monitoring or SCADA integration over networks. Step-by-Step Integration Guide (For Relay + PLC + SCADA Setup) Step 1: Identify Panel Outputs Locate terminals for: Step 2: Select Input Type in PLC Use either: Step 3: Wiring Connections Step 4: Create PLC Logic Example conditions: Step 5: SCADA Tag Configuration Map the PLC inputs to SCADA HMI tags: Use color codes, audible alerts and popups. Step 6: Testing & Validation Example Use Case: AHU Shutdown During Fire Objective: Stop AHU when fire alarm is detected. Flow: This prevents smoke spread and meets NFPA norms. Integrating with MODBUS RTU over RS-485 If deeper monitoring and control are needed, this method is ideal. Steps: ✔ Suitable for plants with multiple zones and fire loops✔ Less wiring compared to relay logic What About SCADA Platforms? GST panels can be integrated with: Protocols supported via gateway or PLC: Tags You Can Map in SCADA Tag Name Source Function FIRE_ALARM_ACTIVE Relay / MODBUS Main alarm trigger ZONE_1_STATUS MODBUS / Gateway Detects zone fire PANEL_FAULT Relay Panel malfunction MCP_TRIGGERED Digital input Manual call point activated LOOP_SHORT Register Wiring fault SUPERVISORY Relay Maintenance alert Safety and Compliance Considerations While integrating, never compromise the standalone integrity of the fire alarm system. Recommended Hardware Accessories Component Use 24V DC Power Supply PLC module power Signal Isolator Protection between systems Relay Interface Module Prevents overloading Protocol Converter For MODBUS/BACnet/IP Shielded Cable Reduces noise on RS-485 Limitations to Keep in Mind Who Should Implement the Integration? Coordination between safety and automation teams is essential. Final Verdict: Is Integration Worth It? Absolutely, integrating GST fire alarm panels with PLC and SCADA is not only possible but highly beneficial in industrial environments. You Gain: Whether you choose relay-based connection or MODBUS communication, the system remains reliable and compliant if implemented correctly. Read Also: Buy GST Conventional Detectors & Devices for Enterprises Read Also: Top 10 Common Programming Mistakes Engineers Make in GST Addressable Panels