Smoke Alarm Buyers Guide
Although it’s not always a pleasant consideration, thinking about the risk of fire is important. Having a functioning smoke alarm installed is one of the easiest and most effective ways of protecting your property against fire. However, you may have to look at a range of fire safety systems before you find the best one for your needs.
Statistics on smoke alarms and house fires in Australia
Serious house fires can result in extensive property damage and even death. According to the Australian Bureau of Statistics, more than half the number of deaths caused by accidental fires or flame injuries occurred in a home fire. While the total number of fatalities caused by fire fell by about 47 percent from 1968 to 1998, those resulting from residential fires dropped by 20 percent only.
House fires are more prevalent during the colder months and account for 1.5 percent of preventable deaths in Australia. Approximately 44 percent of residential fires occurred in the kitchen, 30 percent of which resulted from cooking.
With an increase in the number of deliberately set fires, suspicious and incendiary fires are becoming more common. Unfortunately, these two generally cause more damage than accidentally ignited fires.
According to statistics, 90 percent of separate houses have a fire safety measure while only 68 percent of units, flats, and apartments had one installed. However, fires that occur in units, flats, and apartments have a greater potential for fatality due to proximity. As such, installing a fire safety measure in higher density areas is just as important as it is in separate homes.
Compared to privately owned properties or those rented from a public housing authority, properties rented from real estate agents or private landlords were less likely to have a type of fire safety measure installed.
Smoke alarm laws in Australia
In Victoria, the law mandates that smoke alarm systems must be installed in residential properties. Although the exact requirements may vary per state, the smoke alarm installed has to meet every fire safety requirement applicable to the property’s year of construction.
Properties constructed before February 1998 can have smoke detectors that feature a replaceable battery. On the other hand, those built after 1998 must have either a mains powered smoke alarm system or one driven by a non-removable battery. However, the battery needs to have a lifespan of ten years. Smoke alarms have to be a permanent installation.
Only licensed electricians may install smoke alarms, and they must have the permission of local authorities. It’s illegal for homeowners to perform any electrical installation or repair work in their homes. Non-compliance with smoke alarm laws might lead to criminal charges or civil penalties.
How smoke alarms work
Optical smoke alarms: Also known as photo-electric smoke alarms, this type applies the light scatter principle. They comprise of a pulsed infra-red LED that checks for smoke particles by pulsing a ray of light into the sensor chamber after every 10 seconds. In the absence of smoke, this beam keeps passing in front of the sensor. Once a fire breaks out, smoke enters the optical chamber through vents. As the smoke crosses over the ray of light, its particles scatter some of the infra-red light onto the photodiode light receptor, which triggers the alarm by sending a signal to the integrated circuit.
Ionization smoke alarms: This type ionizes the air between two oppositely charged electrodes as the alpha particles pass through the chamber, creating a small constant electric current. When there is a fire, the smoke particles that enter the chamber absorb the alpha particles, charging the balance of current. This change in current will only occur if enough smoke enters the chamber. The uninterrupted electric current sends a signal to the integrated circuit, causing the alarm to sound.
High-quality smoke alarms feature insect screens to keep bugs from entering the chamber, reducing the likelihood of false alarms.
Types of smoke alarms
There are about five different types of smoke alarm systems, these are:
- Ionization smoke alarms
- Photoelectric smoke alarms
- Combination smoke alarms
- Projected beam smoke detectors
- Aspirating smoke detectors
Residential homes only use the following three smoke alarms.
Ionization smoke alarms:
In general, this type consists of a radioactive source that emits alpha particles, and an ionization chamber. They are highly sensitive, and prone to false alarms. They are not recommended to be installed in kitchens.
Photoelectric smoke alarms:
This type is a nephelometer or scattered light sensor that consists of a light source, a lens for focusing light into a projected beam, and a sensor angled to the beam. Thanks to the optical technology, photoelectric smoke alarms are not as prone to false alarms as their counterpart.
Combination smoke alarms:
This type includes the features of both the ionization and photoelectric alarm systems. While the photoelectric technology responds to smoldering, low-energy fires, the ionization technology responds to rapid, high-energy fires.
Smoke detectors are also classified in two categories, namely:
Hard-wired smoke alarms: This type is wired to your household’s main electrical circuit.
Battery operated smoke alarms: This type is generally powered by a 9V detachable or non-removable battery. Lithium batteries are long-lasting and can last as much as 10 years.
Which is best?
Ionization smoke alarm:
The thought of radioactive isotopes hanging in your home frightens some people. Quick death by fire might not sound as bad as a slow death by radiation. You should, however, rest easy since the alpha particles contained have very little penetrative power and cannot get through the plastic. Furthermore, if the alpha particles escaped by any chance, they cannot travel far. Because of the alarm’s design and the amount of Americium contained, your health is not at risk. This will, however, depend on whether you tinker with the chamber and inhale or ingest the particles. The disadvantage is that old ionization detectors call for proper disposal because of the radioactive isotope. Additionally, the alarm is extremely sensitive, and therefore prone to false alarms.
Photoelectric smoke alarms:
These smoke alarms are not nearly as sensitive as the ionization smoke detectors. They do not contain any radioactive isotope and therefore not a health hazard. Unlike the ionization smoke alarms, you can install a photo-electric smoke alarm in the kitchen area.
If you are not sure about the best smoke alarm to get, having a professional assess your building might help. Regardless of the type you select, you must have your smoke alarms professionally installed, and adhere to all testing and maintenance instructions. If you would like to ask a question contact Pro Electrician Melbourne for professional non biased advice.
What to look for
When it comes to choosing a smoke alarm, compliance with Australian Standard 3786 is the most important feature. Make sure the Australian Standard’s logo is clearly displayed on the package. Here are some of the other features to look for:
- Long-life lithium batteries (10-year lifespan)
- Low battery level warnings
- Integrated emergency exit lights
You can get a basic ionization smoke alarm for as little as $10, and the photoelectric type for $20. However, more advanced photoelectric units can cost up to $100. For standalone smoke detectors:
- A 9V battery-powered dual sensor photoelectric smoke alarm costs about $55.00
- A 9V battery-powered ionization smoke alarm costs around $9.98.
- A lithium battery-powered photoelectric smoke alarm that features an escape light costs $58.50.
On average, setting up one smoke alarm costs around $150, but the price might vary depending on factors such as access and whether you need the alarms interlinked.
Other cost variations include:
- Type of ceiling
- Size of the home
- Whether the structure is concrete or timber
- Whether it’s single-story or multi-story
Getting quotes from different technicians might help you get a better sense of the current market rates. Remember, every price listed above is indicative, subject to market forces, and may vary locally.
Tips from the Pro
When choosing a smoke alarm system, there are other factors to consider besides the type of sensor. These variables include:
Location: Smoke can set off ionization alarms, so photoelectric alarms are the best choice for the kitchen. You need to place a smoke alarm near the kitchen because cooking is the leading cause of residential fires.
The size of your property: Most houses need to have a smoke alarm installed in every room, attics and basements included. You may need to place smoke detectors in both ends of the stairways and hallways near bedrooms.
You can determine the fire risks to your property and the most suitable type of smoke alarm to install by conducting a complete fire-risk assessment. As such, engaging the services of a professional might be the best option. Remember, smoke alarms are key to life safety.