How a Smoke Detector Works

When you see smoke, you know there’s a fire somewhere. At night, and when you are sleeping, detecting and seeing smoke is impossible. The consequences can be fatal. It’s therefore important to install a smoke detector in your home. But the first question is, how do smoke detectors work?

In this blog post, we will answer this question, look at the types of smoke detectors, and discuss their advantages and disadvantages. Read on to learn more.

What a Smoke Detector Does

Smoke detectors are designed to sense smoke and alert people to a possible fire. They are fitted with a sensor and an electronic alarm system. Using an in-built technology, the sensor will sense smoke through little traces of it in the air. 

Once it senses the small traces to the required degree, a signal is transmitted to an electronic alarm. This alarm will then be set off and alert you. 

Smoke detectors save lives. The leading cause of death by fire is smoke inhalation and exploding fires that catch you unawares. These devices not only save lives but also reduce the number of deaths by fire by a large percentage.

The Two Types of Smoke Detectors

There are two well-known types of smoke detectors – photoelectric and ionization.

Ionization smoke detectors detect tiny smoke particles in the air through a safely designed radioactive material. When the device senses the tiny particles to the degree it’s created to detect, the alarm goes off.

Photoelectric smoke detectors have a light beam inside the sensor. When the beam senses smoke, it reflects onto a sensor and the alarm goes off.

How a Photoelectric Smoke Detector Works

Photoelectric smoke detectors have a light source that can be found inside a sensing chamber. When the chamber detects a smoke, the light will be reflected onto the sensor, thus causing the alarm to be triggered.

There are two types of photoelectric smoke detectors. For the first type, smoke can block the in-built light beam. With reduced light reaching the photocells, it sets off the alarm. For the second type, which is the most popular type, light is distributed by the smoke fragments into the photocell, triggering the alarm.

How an Ionization Smoke Detector Works

Ionization smoke detectors contain two of both electrically charged plates and chambers. One chamber is the ionization cell, while the other is the place for ionizing radiation that helps sense the smoke. The radioactive material used in this device is safely designed to protect you from the dangers of radioactive materials.

When the device senses smoke, the flow of ions between the two charged plates is disrupted. This reduces the flow and sets off the alarm.

Pros and Cons

Photoelectric Smoke Detectors

This type of detector is perfect for fires that burn slowly but with large amounts of smoke. Such fires are caused by cigarettes, electric shorts and fireplace embers. These fires take place in carpeting, bedding and stuffed furniture.

The benefits of photoelectric smoke devices are:

  • They are highly sensitive to fires that burn slowly. They will alert you early before the fire bursts into flames. This allows you to run for safety before it’s too late.
  • Fewer false alarms especially around the kitchen

The cons include:

  • It takes a huge amount of smoke to trigger the alarm

Ionization Smoke Detectors

This device is more sensitive to fires that burn faster but with less smoke. Such fires are caused by flammable liquids, cleaning products, gasoline, cooking grease and newspapers.

The pros of ionization smoke detectors include:

  • Sensitive to flaming fires

The drawbacks are:

  • Can trigger false alarms from the kitchen and bathroom’s steam
  • Respond slowly to slow-burning fires


Smoke detectors can make the difference between losing your home and even life and death. They are therefore a must-have safety device in your home. You’ll need a licensed electrician to help install your new smoke detector.