How prepared is your home for fire? A lot of people think of an engulfing house fire as a killer but it’s really important to remember that smoke is just as dangerous. Smoke from a fire can render someone unconscious by limiting their oxygen supply, making it impossible to escape without assistance. A smoke detector is your early warning system to wake up, take your loved ones and get out of a property before the flames take hold.

What a smoke detector does

All Australian standard home smoke detectors come with two functions; a smoke detection system and a very loud alert to wake people up and draw attention to danger.

While typical home smoke detectors are connected to an internal 9-volt battery, these will need regular changing in order to get a fast and reliable response. Unfortunately, many cases of fatal home fires have been because smoke detector batteries were allowed to run flat or had been disabled. A way to avoid the constant need to refresh batteries is to have an electrician hard-wire smoke detectors to your home electricity current.

The two types of smoke detectors

Some fires smoulder and some flame. To cater to these different types there are two types of smoke detector technologies that are specialised to detect different fire types, photoelectric smoke detectors and ionisation smoke detectors.

How a photoelectric smoke detector works

Usually, photoelectric sensors use a light beam and sensor to trigger a sound when there is a disruption to the light. When no light reaches the sensor, even momentarily, it can sound and alert, however, for smoke to be able to cut off a light beam, you’d need a significant amount of it before getting a result, which might be too late to limit damage or save lives.

Rather than having continual contact with a light source, photoelectric smoke detectors have an internal chamber that sets a light source and sensor at 90-degree angles to each other. Rather than hit the sensor, the job of the light is to miss, leaving the sensor in the dark. This distance enables the chamber to sense even small changes in the atmosphere. Any smoke, even small amounts, in the chamber will cause the light to scatter in different directions, alerting the sensor and triggering the alarm.

The technology is simple and cheap to produce and very effective as an early warning system for smouldering fires.

How an ionisation smoke detector works

Ionisation detectors have an ionisation chamber that works with two plates (one positively charged, the other negatively charged). A minuscule amount of radiation is used to offset the electron particles and start a current. Any smoke entering this space disrupts the process and reduces the current, setting off the alarm.

Pros & cons

A photoelectric is best suited to slow fires that fester without much flame, while the ionisation smoke detector is best for times when there is very little smoke and a raging flame. To cover both these scenarios it’s best to choose a smoke detector that offers both technologies in one. You can find out what type of smoke detector works best for you by talking to a professional electrician about types, installation and benefits.

Having a smoke detector on its own is not enough, the smoke detector you have needs to be reliable. The wrong location, a flat battery, removed battery or faulty device offers a false sense of security and no protection to you or your home. Make sure you test the alarm frequently, keep the sensor free from dust and change the battery once a year.