Introduction

An Emergency Light is an essential electrical device that automatically turns ON during a power failure and provides illumination using a battery-powered light source. Emergency lighting systems are widely used in homes, offices, hospitals, schools, and public buildings to ensure safety during power outages.

This project demonstrates how an automatic emergency lighting system works using basic electronic components.

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Objective of the Project

The main objectives of this project are:

• To provide automatic lighting during power failure.
• To eliminate the need for manual switching.
• To understand battery charging and power switching concepts.
• To design a reliable backup lighting system.

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Working Principle

The emergency light operates based on mains power detection and battery backup.

Normal Power Supply Condition

• When mains power is available, the battery gets charged.
• The emergency light remains OFF.
• The relay or transistor stays in a normal state.

Power Failure Condition

• When mains power fails, the relay changes its state.
• The battery supplies power to the LED or lamp.
• The emergency light automatically turns ON.

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Components Required

Basic Emergency Light Circuit

• Rechargeable Battery (6V / 12V)
• LED / LED Panel
• Relay (SPDT)
• Diodes
• Resistors
• Transformer
• Bridge Rectifier
• Capacitors
• Power Supply

Arduino-Based Emergency Light (Optional)

• Arduino Uno
• Relay Module
• Battery
• LED
• Jumper wires

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Circuit Diagram

Basic Emergency Light Circuit

AC Mains
   |
Transformer
   |
Bridge Rectifier
   |
Battery Charging Circuit
   |
Relay (SPDT)
   |-------- AC Available → Light OFF
   |-------- Power Fail → Battery → LED ON

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Arduino-Based Circuit

Mains Detect ---- Arduino D2
Relay ---------- Arduino D8
LED ------------ Battery + Output
GND ------------ Common Ground

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Arduino Code for Emergency Light

int mainsDetect = 2;
int relayPin = 8;

void setup() {
  pinMode(mainsDetect, INPUT);
  pinMode(relayPin, OUTPUT);
}

void loop() {
  if (digitalRead(mainsDetect) == LOW) { 
    // Power failure detected
    digitalWrite(relayPin, HIGH);
  } else {
    // Mains power available
    digitalWrite(relayPin, LOW);
  }
}

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Advantages

• Automatic operation
• Reliable backup lighting
• Easy to use
• Enhances safety
• Low maintenance

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Applications

• Homes and apartments
• Hospitals and clinics
• Schools and colleges
• Emergency exits
• Offices and commercial buildings