Photoelectric Versus Ionisation Technology: What’s the Difference?

The smoke alarm is an essential safety device for every business and home, so it’s crucial to purchase a model that provides adequate warning in the event of an emergency. Not only is having an effective smoke alarm important for safety, it’s also a mandated legal requirement throughout Australia.

If you’re in the market to purchase a new smoke alarm for your rental property, business, or home, you might be wondering which variety is best: photoelectric or ionisation.

In this post, we’ll explain the difference between the two and outline why photoelectric is the safest bet. We’ll also cover what to look for when making a purchase so you can identify the ideal smoke alarm solution for your needs.

What’s the difference between a photoelectric and ionisation smoke alarm?

Both these common smoke alarm types are designed to provide the occupant with an early warning in the event of a fire, giving them sufficient time to vacant the premises—however, the two function in distinct ways.

The ionisation alarm incorporates a radioactive element that produces a low level of radiation, which is harmless to humans. When air molecules come into contact with radiation, they become electrically charged in a process we call ionisation. The system analyses the electrical charge in the air, which heightens when smoke is present. And should the charge be higher than usual, the device will trigger an alarm.

Photoelectric alarms, on the other hand, incorporate an electric component to create a beam of light and analyse how effectively it illuminates the air. When smoke starts to infiltrate a room, its heavy particles inhibit the ability of light to pass through the air. Once the light beam dims to a predetermined level, the system will trigger an alarm.

What’s better: a photoelectric or an ionisation smoke alarm?

Most fire safety professionals agree the photoelectric system is superior in the family home. More importantly, all of the relevant Australian authorities recommend photoelectric alarms as the standard smoke detection type across the country. In addition, Queensland now mandates the use of photoelectric alarms on newly constructed or renovated homes.

Ionisation smoke alarms are especially sensitive to the tiny particles produced by strong blazing flames. In rare situations where a large area should catch on fire rapidly, ionisation may yield better results. However, they have been, or are gradually phasing out in Australia and old ones need to be disposed of safely.

Photoelectric alarms perform better at detecting larger particles that come from slow, smouldering flames. Because the vast majority of house fires smoulder for some time before erupting into blazing flames, photoelectric smoke alarms typically provide more warning than ionisation models.

Another major advantage of photoelectric units is they produce fewer nuisance alarms from everyday activities like cooking. Excessive nuisance alarms often tempt the householder to turn off the smoke alarm system, which can be a deadly mistake.

What to look for in a smoke alarm?

Now you know why photoelectric is best, it’s time to delve into some of the other features that make for a good smoke alarm.

  • Mains powered: Australian law dictates all newer homes should have at least one mains powered smoke alarm with a backup battery.
  • A long back up battery life: The ideal smoke alarm comes with a 10-year backup battery, preferably one that’s permanently fixed in place. Although cheaper, a system with a shorter battery life will have to be changed manually—and let’s face it, chances are you’ll forget.
  • An accessible test button: Fire safety professionals recommend you check your alarm is functioning correctly every month by pressing the test button. Because most smoke alarms are positioned on the roof or some other hard-to-reach place, you may prefer one you can test via torchlight or remote control.
  • A hush button: If you’ve got a tendency to burn toast, you’ll quickly grow tired of dealing with all those nuisance alarms (especially if you’re running an ionisation model). A hush button lets you instantly deactivate the noise for a set timeframe, usually around 30 minutes or so. Again, choosing a model with a remote control will make the process easier.
  • An escape light: If a house fire causes a blackout—which it often does—then an escape light will help you navigate through the darkness towards safety. Because escape lights run off batteries, the feature will still function after your 240V electrical system fails.
  • Interconnectivity: If you’ve got a large property spread over a substantial area, not everyone will hear an alarm sounding at the other end—the same logic applies to small houses with soundproof rooms. An interconnected smoke alarm will trigger all other devices within the same system to ensure everybody gets the message loud and clear.
  • Insect screens: An insect screen will prevent bugs from crawling into the device and setting off a nuisance alarm. Be sure to vacuum clean it every year, so dust doesn’t accumulate and inhibit the sensitivity of the unit.

What regulations govern smoke alarms in Australia?

The Building Code of Australia mandates that all homes built or renovated, since 1997, must have a 240V mains powered smoke alarm with a backup battery. Furthermore, each state has additional requirements that apply on top of the federal code.

  • NSW: Photoelectric recommended. At least one per level or apartment, and at least one in every corridor connected to a bedroom.
  • QLD: Photoelectric mains-powered alarm with backup battery required for houses built or renovated since January 2017. Alarms under 10 years old must be replaced as they expire.
  • VIC: Photoelectric recommended. At least one alarm per home.
  • SA: Many homes require a mains-powered alarm with a 10-year backup battery. At least one alarm must be installed per home.
  • WA: Many homes require a mains-powered alarm with a 10-year backup battery. At least one alarm must be installed per home.
  • TAS: All homes renovated or built from 1997, and all rental properties, regardless of age, must have at least one mains-powered alarm with a 10-year backup battery.
  • NT: At least one alarm must be installed per home. New installations must be photoelectric mains-powered or 10-year battery alarms.
  • ACT: Photoelectric recommended. All homes renovated or built from 1997 must have at least one mains-powered alarm.

Now we’ve covered the relevant specifications, features, and regulations, we invite you to peruse the high-quality selection here at PSA Products, Australia’s leading smoke alarm supplier. We recommend you take a look through our popular Lifesaver smoke alarm and HomeGuard smoke alarm range to find the perfect model for your rental property, business or home.