The time we set our clocks back to standard time is also the time most Fire Departments suggest you replace the batteries in your smoke detectors.
Does your home have smoke detectors? If so, do you know if they’re actually working?
Most homes these days have smoke detectors. Perhaps not in every location where one should be, but usually at least one in the house.
This post is a quick overview of how to select and use smoke detectors to ensure your house and your family are protected from fires.
There are two main types of smoke detector technology: ionization and photocell.
Ionization smoke detectors are the most common and usually least expensive of smoke detectors. They have a small amount of radioactive material (not enough to be dangerous) between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, thus reducing the flow of current and activating the alarm
Photocell smoke detectors are less common, but more sensitive and more expensive. They work by aiming a light source into a sensing chamber at an angle away from the sensor. When smoke enters the chamber, it reflects light onto the light sensor; triggering the alarm
You can find smoke detectors that use both technologies, and these are probably the safest because one smoke detector can detect both active fires and fires that are smouldering and not yet active.
Smoke detectors can be powered in one of two ways: battery or hard-wired.
With battery powered smoke detectors, the advantage is that they can be placed anywhere in the house.
Hard-wired smoke alarms are wired directly into your home’s electrical circuits. They are installed using a junction box in the ceiling – the same kind of box used for lights. They also can be purchased with battery backup feature so that, if your home lost power – for example due to an electrical fire – the battery would provide enough power to trigger the alarm.
Interconnect Your Smoke Alarms
Hard-wired smoke detectors can also be interconnected so that if a detector on one floor detects a fire, it can sound the alarm on all smoke detectors in the house. This can be useful if a fire were in the basement and the alarm there might not be audible in your bedroom upstairs.
When interconnected smoke alarms are installed, it is important that all of the alarms are from the same manufacturer. If the alarms are not compatible, they may not sound.
A 2009 study done in the US shows just how much interconnection improves safety.
- When smoke alarms (interconnected or not) were on all floors, they sounded in 37% of fires and alerted occupants in 15%.
- When smoke alarms were not on all floors, they sounded in only 4% of the fires and alerted occupants in only 2%.
- In homes that had interconnected smoke alarms, the alarms sounded in half (53%) of the fires and alerted people in one-quarter (26%) of the fires.
Why didn’t the smoke alarms go off 100% of the time? One probable reason is that some of the smoke detectors had dead batteries. Another is that some of the alarms may have been rendered useless because they had accumulated dust and other materials that prevented the sensors from working properly.
Caring for Your Smoke Detectors
Smoke detectors are really only reliable up to 10 years from date of purchase (not just when you actually install them), so you should plan to replace them every ten years. Some detectors have a feature that sounds a brief chirp as the unit approaches the end of its useful life.
Yes, it’s a pain to have to replace smoke alarms, but they only cost about $30 and what price can you put on the safety of your home and family?
Fire Departments are right to suggest replacing the batteries every year, and the end of daylight savings time is an easy time to remember to do so. Fresh batteries help ensure your unit is going to sense a fire, should it break out.
Periodically, you should vacuum the housing for your smoke detector to ensure the vents that allow air to circulate to the sensors are clear of dust and other material. Use the drapery or upholstery attachment, which have soft bristles that can penetrate the vent holes and loosen up dust that may have accumulated.
Lastly, test your smoke alarm once a month to ensure it is working properly.
An excellent resource to learn more about smoke detectors is the National Fire Protection Association.
The Ontario Association of Fire Chiefs has a brochure called Working
Smoke Alarms Save Lives that you can download.