IoT-Based Multi-Sensor Fire Detection and Automated Suppression System with Electrical Isolation

Abstract

This article describes the creation of an Internet-of-Things (IoT)-based system to automate the detection and extinguishing of fire in multi-story buildings to make them reliably safe from fires in real-time. The system uses three sensors, DHT11, MQ2, and IR; a fire will only be identified as having occurred if all three sensors have simultaneously detected an abnormal condition. The real-time monitoring of the three-sensors will be performed by an ESP32 microcontroller, which will disconnect the electrical load through the use of an electrical relay and activate a water-spray system for fire suppression. A prototype building was constructed with four floors, including eight electrical loads connected in parallel and powered by a battery. When a fire is detected, the ESP32 will disconnect the electrical supply using a relay (to avoid the chance of a short circuit) and turn on a motorized water pump to put out the fire. The system allows for real-time monitoring of the situation by using the Adafruit IO dashboard; notification systems, including email, are utilized to alert the user via IFTTT webhooks. Electrical isolation will prevent an electrical short circuit and ensure personnel are not harmed while the water is dispensed. Testing the performance of the entire system resulted in an average response time of less than 1.5 seconds and zero false alarms. The proposed system can be used as an automated, reliable, and low-cost approach to protecting smart building from fire.

Introduction

The text presents an IoT-based multi-sensor fire detection and automated suppression system designed to improve fire safety in residential and industrial environments.

Traditional fire detection systems often rely on a single sensor (smoke or heat), which leads to false alarms and unreliable detection. To solve this, the proposed system uses a multi-sensor approach combining a DHT11 temperature sensor, MQ2 smoke sensor, and IR flame sensor. Fire is confirmed only when all three sensors detect abnormal conditions simultaneously using an AND-based decision logic, which significantly improves accuracy and reduces false alarms.

The system is built around an ESP32 microcontroller, which continuously processes sensor data and triggers responses when fire is detected. Once confirmed, the system:

• Activates a buzzer alarm
• Cuts off electrical power using a relay (electrical isolation for safety)
• After a short delay, activates a water pump for fire suppression

It also integrates IoT connectivity (Adafruit IO and IFTTT) to enable real-time remote monitoring and alert notifications.

The architecture consists of:

• A sensing layer (temperature, smoke, flame sensors)
• A processing layer (ESP32 decision-making and control)
• An electrical load system (multi-floor controlled power distribution)
• A suppression mechanism (relay-controlled water pump)

A key safety feature is sequential operation, where power is disconnected before water is released to prevent electrical hazards. The system is also battery-backed to ensure continuous operation during power failures.

Conclusion

This paper presents a multi-sensor fire detection and automated suppression system using multiple sensors that communicates over the Internet of Things(IoT). The Fire Detection and Suppression System utilize temperature, smoke, and flame sensors along with logic to verify that there is indeed a fire present, which reduces false alarms and eliminates the need for human verification. The system detects fires in less than 1.5 seconds. To enhance the reliability and safety of the utility supply to the fire protection equipment, we designed the system to disconnect the supply before powering up the water suppression system. The water suppression system can be powered from battery-backed parallel loads, ensuring that it operates during a power failure as long as the battery backup is functional. Also, since the two circuits (control and suppression) use separate power sources, when one fails, it provides continuity to the other. The integration of Adafruit IO and IFTTT into the system provides the ability to monitor in real-time and send alerts outside of the facility with limited infrastructure that can improve situational awareness during an emergency. The proposed system represents a reliable, cost-effective, and scalable solution to smart fire safety applications. Additionally, future enhancements for the proposed system could include increasing the number of nodes in the system, adding gas detection devices such as CO and CO?, and implementing advanced data techniques for detecting a fire with greater accuracy.

References

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Copyright

Copyright © 2026 Dr. Y. Mastanamma, Sadiya Shiraz, Karishma Naaz, R. Dharani Divyashree. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.