Smoke Alarms - FRFD

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Smoke Alarms


Flames are what cause the structural damage in a typical house fire, but it is smoke that is the primary danger to people. The smoke and fumes that are produced in a structural fire are highly toxic and the majority of house fires causing death are due to smoke inhalation.

Modern homes contain many materials such as wood, nylon, and plastics; when these materials burn they produce heavy smo
ke and toxic fumes such as cyanide gas and carbon monoxide. Many of these materials can smoulder and produce considerable amouts of smoke and fumes long before they burst into visible flames.

If you are sleeping when a fire starts, you may suffer from smoke inhalation before you wake up. Smoke alarms do save lives and it is not safe to rely on a barking dog, or the smell of smoke to alert you of danger and awaken you. In fact, the combination of toxic gases and smoke, along with reduced levels of oxygen, can make waking up very difficult and in some tragic circumstances, nearly impossible. It is therefore vital that working smoke alarms that will detect smoke and sound an alarm be installed and maintained in your home.

The following FAQ aims to answer questions about smoke alarms, their types, usage, installation, maintenance and regulations.


More than 90% of residential fires in Ontario are considered to have been preventable.
1 out of 17 preventable home fires results in a reported injury, and not all injuries are reported.
Fatality occurs in 1 out of every 100 preventable home fires.

Research conducted between 1995 and 2004 concluded the following facts regarding smoke alarm usage in preventable residential fires causing detah in Ontario:

In 35% of the cases - a smoke alarm was present and did operate
In 25% of the cases - a smoke alarm was present but did not operate
In 21% of the cases - no smoke alarm was present
In 19% of the cases - a smoke alarm was present but its operational status could not be determined

These figures pertain to 609 residential fire related fatalities in Ontario during the period of this study. In nearly half of these fatal home fires there was no early warning from a smoke alarm. In the majority of these cases, it was determined that a dead battery, or a smoke alarm with no battery, was the reason for the alarm failing to activate.

Statistics also reveal that the holiday season between the beginning of November and the end of January is the greatest period in which residential fire fatalities occur. Between November 1, 2004 and January 31, 2005, there were 35 fire related fatalies in ontario alone
. This highlights the need to be extra vigilant during this holiday period; ensuring that smoke alarms have fresh batteries installed at the beginning of the winter holidays could help reduce the risks involved should tragedy strike.

Are There Different Types of Smoke Alarms?

There are two types of technologies, ionization and photoelectric, used in the production of smoke alarms. These devices are designed to sound an alarm when the detection of smoke or other products of combustion occurs.
Each type of alarm has its advantages and disadvantages and available products may use one or both technologies in a single unit.

Both types of alarms will alert you to a fire and may save lives when properly installed and maintained. It is a wise practise to purchase the highest quality alarm that your buget will allow - do not select a detector solely based on its low cost.

Smoke alarms may be battery operated or hard-wired into your home's electrical system. When replacing old or worn smoke alarms, it is important that the correct type of alarm be chosen as a replacement; h
ard-wired (or direct-wired) alarms cannot be replaced with battery-powered units.

Make sure that the produt that you have chosen has been manufactured and tested to an acceptable standard; this is indicated by a marking by the Underwriters Laboratories of Canada (ULC), or Underwriters Laboratories Incorporated (cUL).

Ionization Smoke Alarms
Ionization smoke alarms work by using a small amount of radioactive material (americium 241) that ionizes the air between two electrically charged plates. When smoke enters the chamber, the current of the elctrical flow is changed; the alarm is activated when this change is detected.

This type of alarm will activate more quickly for fast, flaming fires where there may be little visible smoke.

Table 1 — Qualities of Ionization Smoke Alarms



Cheaper than other types of smoke alarms

Very susceptible to nuisance alarms due to cooking

Very good with fast flaming fires with little visible smoke

May be slow to respond to slow smouldering fires

Suitable for general use

Contains radioactive material

Less prone to false alarms caused by dust and steam

Photoelectric (Optical) Smoke Alarms
In a sence, photoelectric smoke alarms "see" the smoke. The term photoelectric does not refer to the power source for the alarm as they may be either battery-powered or direct-wired. These alarms operate on the principle of scattered light reflecting off of the large air-borne particles that make up heavier, dense smoke. The scattered light then strikes a sensor which activates the alarm.

In normal conditions, there a a light source inside the alarm that emits a beam that shoots across to the other side without striking the sensor. It is only when smoke enters the chamber that this beam is disrupted and the light becomes scattered, thus striking the sensor which causes the alarm to sound.

Photoelectric smoke alarms are particulary more responsive to smoldering fires and the dense smoked produced by foam-filled furnishings.

Table 2 — Qualities of Photoelectric Smoke Alarms



Good for smouldering fires and dense smoke

Prone to nuisance alarms from dust and insects – must be kept clean

Not as prone to cooking nuisance alarms

More expensive

Contain no radioactive material

Suitable for general use

Ionization / Photoelectric Combination Smoke Alarms
Combination Ionization / Photoelectric alarms combine the two technologies to detect the presence of smoke or products of combustion. An alarm can be activated by either of the sensors within the unit. A combination Ionization / Photoelectric alarm gives you the benefits of both types of technologies.

Combination Smoke Alarm / Carbon Monoxide Alarm
larms that combine smoke and carbon monoxide detection capabilities are also available in a single unit. These units incorporate different sounding alarms, or in some cases voice alerting of “Fire / Fire” or “Warning Carbon Monoxide” when detecting the presence of smoke and/or carbon monoxide. If a combination smoke alarm / carbon monoxide alarm is used, it must be installed on the ceiling to ensure that it will detect smoke effectively. Follow the manufacturers instructions.

Battery-Operated Smoke Alarms and Direct-Wired or Hard-Wired (A/C) Smoke Alarms
A 9v alkaline battery powers most battery-operated smoke alarms. Some manufacturers also offer battery-operated smoke alarms powered by a long-life lithium battery.

Direct-Wired alarms are powered by a permanent connection to the household alternating current (AC) electrical supply (110v). Many of these models also offer a battery-powered backup feature to provide protection when the power goes out.

Are There Smoke Alarms Made for Individuals with Impaired Hearing?

he Ontario Building Code and the Ontario Fire Code both require the installation of smoke alarms in all residential occupancies. By definition, a smoke alarm must sound an audible alarm to alert the home’s occupants. Unfortunately, an audible alarm may not alert an individual with a hearing impairment.

There are numerous smoke alarms available that address the specialized needs of
these individuals. Some devices utilize a bright flashing strobe light, as well as an audible alarm, to alert the residents in the event of a fire. Due to the electrical supply requirements to operate these strobe lights, they must be wired directly into the home’s 110v A/C electrical system. Some models have a 9v battery backup that will ensure that the audible alarm will activate in the event of a power failure, however the battery will not activate the strobe light.

Additional options also exist that allow the individual to connect their smoke alarms to an alerting system that may, for example,
incorporate a flashing strobe light, vibrating pager and/or vibrating bed shaker to alert the resident to the emergency.

A catalogue detailing all available options for the deaf, deafened or hard of hearing is available through The Canadian Hearing Society. Visit
their website today at and click on the estore menu to browse through the available product lines.

Where and How Should Smoke Alarms Be Installed?

The Ontario Fire Code requires all single family, semi-detached and town homes in Ontario, whether owner-occupied or rented, have a working smoke alarm on every storey of the residence, including the basement and outside all sleeping areas. Smoke alarms are not required in individual bedrooms unless required by the Ontario Building Code at the time of construction. T
o help ensure ultimate protection hoowever, we encourage smoke alarms be installed in each bedroom within the residence; especially where bedroom doors are closed at night.

As illustrated below, a storey can consist of more than one level. When a home contains multiple sleeping areas, a smoke alarm must be installed to protect each separate sleeping area. This may necessitate additional smoke alarms on some levels of a split-level home. The following illustrated example of a split-level home, indicating required smoke alarm placement, is provided for clarification. Note that since smoke rises, the smoke alarm serving the 1st storey is installed in the upper level of that storey.

NOTE: Both the upper and lower levels of the 2nd storey require smoke alarm installation
due to separate sleeping areas contained on both levels. However, only one smoke alarm
is required to service both the upper and lower levels of the 1st storey since neither level
contains a sleeping area. Also note that since smoke rises, the smoke alarm serving the
1st storey is installed in the upper level of the 1st storey.

Read and familiarize yourself with the manufacturer’s instruction manual. Always follow the manufacturer’s instructions for
installing, testing, and maintaining smoke alarms.
Smoke, heat and combustion products rise to the ceiling and spread horizontally. In order for the smoke alarm to properly
sense the presence of smoke, the ideal location is on the ceiling in the centre of the room. Ceiling mounting is preferred
in ordinary residential construction.
When installing the smoke alarm on the ceiling, ensure it is a minimum of 10cm (4 inches) from any wall.
If wall mounting is necessary, use an inside wall, ensuring it is a minimum of 10cm (4 inches) below the ceiling, but no
lower than 30.5cm (12 inches) below the ceiling.
If the hallway serving the bedrooms is more than 9 metres (30 feet) long, install smoke alarms at both ends of the hallway.
Install smoke alarms at both ends of a room if it is more than 9 metres (30 feet) long.
In stairways with no doors at the top or bottom, install smoke alarms anywhere in the path of smoke moving up the stairs.
However, always install smoke alarms at the bottom of closed stairways, such as those leading to the basement. Dead air
trapped near the closed door at the top of the stairway could prevent smoke from reaching the smoke alarm if installed at
the top of the stairway.

While choosing the location to install an alarm, it is also important to consider the areas in which an alarm should not be installed:

Do not install smoke alarms in “dead air pockets”, for example within 10cm (100mm - 4 inches) of where a ceiling meets a
wall or a corner of a room.

Do not install a smoke alarm within 1 metre (3 feet) of a doorway to a kitchen or bathroom, forced air ducts used for
heating or cooling, ceiling or ventilation fans, air conditioner units or other high airflow areas.
Do not install the smoke alarm where drapes or other objects may block the sensor.
Do not install in the peaks of vaulted ceilings, “A” frame ceilings or gabled roofs. For “A” frame type ceilings, install the
smoke alarm 10cm (4 inches) below the peak. See the illustration below for clarification.

When installing a smoke alarm in a room with a sloped ceiling, position it 90cm (36 inches) horizontally from the highest
point, as illustrated below, since dead air at the peak may prevent smoke from reaching the unit.

Electronic “noise” may cause nuisance alarms. Install smoke alarms at least 30 cm (12 inches) away from fluorescent
Avoid excessively dusty, dirty, greasy or insect-infested areas. Dust particles and insects may cause nuisance alarms or
failure to alarm.
Do not install in areas where the temperature is colder than 4.4ºC (40ºF) or hotter than 37.8ºC (100ºF). Extreme
temperatures may adversely affect the sensitivity of the alarm, as well as diminish the lifespan of the battery, if so
Do not install in areas where the relative humidity is greater than 85% or within 3 metres (10 feet) of showers, saunas,
dishwashers or any other steam-producing appliance. Very humid areas along with steam can cause unwanted
nuisance alarms and adversely affect the battery, if so equipped.
Do not install smoke alarms in your garage. Combustion particles produced when you start your automobile will cause
unwanted nuisance alarms.

Building Code and Fire Code Requirements for Smoke Alarms in Ontario

The Ontario Building Code
has required direct-wired smoke alarms be installed in all new home construction since 1986, with amendments and additional requirements over the years.

When smoke alarms are being replaced, the replacement unit must not reduce the level of detection required by the Building Code in effect at the time of construction of the residence, or by municipal by-laws in effect before the Fire Code adopted this requirement. This requirement is contained in Sentence the Fire Code. In other words, existing direct-wired or hard-wired smoke alarms or electrically interconnected smoke alarm installations must be maintained to provide the same level of protection as originally required. Any replacement smoke alarms must be of a type comparable to the original or better. Any smoke alarms installed in addition to the requirements of Section 2.13 of the Fire Code are permitted to be battery powered.

Direct-wired smoke alarms can be “interconnected” or linked to one another, which means that should one smoke alarm activate in the home it will automatically sound the alarm on all smoke alarms within the home that are connected. People who sleep with their bedroom doors closed or may have difficulty awakening to a smoke alarm sounding outside the sleeping area should strongly consider installing interconnected direct-wired smoke alarms in their home.

Remember, smoke alarms connected directly to your home's electrical power supply (A/C) will not work during hydro outages unless they have a battery backup feature. Some older models of these alarms do not have an internal battery backup. Find out what type of alarms you have in your home and ensure you are protected by battery operated smoke alarms in the event of a power failure in your home.

The Ontario Fire Code
requires all single family, semi-detached and town homes in Ontario, whether owner-occupied or rented, have a working smoke alarm on every storey of the residence and outside all sleeping areas. Failure to comply with the Ontario Fire Code smoke alarm requirements could result in a ticket of $235 or a fine of up to $50,000 for individuals or $100,000 for corporations. The Ontario Fire Code specifies that “no person shall intentionally disable a smoke alarm so as to make it inoperable”. This includes, but is not limited to, removing the battery. A tenant, or any other person, who intentionally disables a smoke alarm is guilty of a provincial offence and may be subject to a fine.

Homeowners are responsible for installing and maintaining smoke alarms.

Landlords are responsible for ensuring their rental properties comply with the law. They must also provide tenants with a copy of the smoke alarm manufacturer’s maintenance instructions. You may download a copy of the
Smoke Alarm Maintenance Checklist” supplied by the Office of the Ontario Fire Marshal here.

Tenants of rental properties should contact their landlord immediately if their occupancy does not have the required number of smoke alarms, or if there are any problems or concerns with the alarms. You may download a copy of the “Smoke Alarm Maintenance Information for Tenants and Occupants in Rental Units
” information sheet supplied by the Office of the Ontario Fire Marshal here.

Using the "Hush" Control Feature on a Smoke Alarm

Occasionally, cooking vapours and steam may cause a smoke alarm to activate even when there is no fire emergency present. These are considered as nuisance alarms and are the principle reason leading to people disabling
their smoke alarms by either removing the battery or disconnecting an alarm from its power supply. This practice if disabling a smoke alarm is extremely dangerous however, and it is against the law.

The Office of the Ontario Fire Marshal has introduced a website,
, that provides detailed instructions on ways to help prevent or eliminate nuisance alarms. Additionally, manufacturers of smoke alarms offer some models that incorporate a "HUSH" or "PAUSE" feature which allows the resident to temporarily silence the nuisance alarm. The HUSH feature will generall silence the alarm for about 7 miutes and then automatically reset itself. The smoke alarm will indicate that it is in HUSH mode by use of a periodic “chirp” or a visual indicator, such as a flashing LED light.

NOTE: Dense smoke will override the “HUSH” control feature and sound a continuous alarm to alert you to a fire emergency.

CAUTION: Before using the “HUSH” feature, identify the source of the smoke and be certain a safe condition exists.

Handling Nuisance Alarms

A nuisance alarm is when your fire alarm is activated although no immediate danger of fire is present. There are a number of conditions that may lead to nuisance alarms, and all of them are avoidable. Some of the more common conditions include vapours created while cooking food, steam from the shower, toasters, dusty conditions, and insects. Should you encounter persistant false, or nuisance alarms, attempt to isolate and resolve the condition by following these simple steps:

Avoid installing smoke alarms in or near kitchens and bathrooms where steam or cooking are present
If a smoke alarm is installed within 6 metres (20 feet) of a cooking appliance it should be a photoelectric (optical) smoke
alarm or one that incorporates a “HUSH” silencing feature
Keep ovens and stovetop burners clean to eliminate minor smoke flare-ups
Clean out accumulated crumbs from the bottom of toasters and/or toaster ovens and turn down the timer setting
Use the kitchen vent hood fan, that exhausts to the outside, when cooking to remove steam and smoke during cooking
Use bathroom ventilation fans, that exhaust to the outside, to remove steam build-up
Relocate the smoke alarm from the ceiling to a spot on an adjacent wall
Move the alarm further away from the source of the nuisance alarm
Replace ionization type alarms with photoelectric (optical) alarms
If your alarm does not have a “HUSH” feature, use a towel or newspaper to fan the alarm to dissipate the smoke or steam.

Visit the O.F.M. "MAKE IT STOP" website at to learn more about nuisance alarms

Testing and Maintaining Smoke Alarms

Read and familiarize yourself with the manufacturer’s instruction manual. Always follow the manufacturer’s instructions for
installing, testing, and maintaining smoke alarms.
Ensure the smoke alarm is secure and unobstructed.
Test all smoke alarms monthly by pressing the “TEST” button. Pick a familiar, meaningful date to help remind you each month,
such as a birth date or anniversary. A broom handle or cane can be used to depress the test button eliminating the need to
climb a ladder or stand on a chair.
Test all smoke alarms after being away from home for more than 7 days. The low battery “chirp” may have activated while you were
away from home and the battery is dead, leaving you without protection.
Once a year test your smoke alarms with smoke from a smouldering incense stick or a smouldering cotton string placed in an
ashtray or other suitable noncombustible container. CAUTION: Smouldering materials used in this test should be disposed of in
a manner that does not create a fire hazard. No open flames from matches, lighters or candles should never be used to test
smoke alarms. Doing so may damage the smoke alarm as well as start a fire in your residence.
Install a fresh battery in your smoke alarms at least once a year or whenever the low-battery warning sounds. Fire Prevention
Week, which is the week of Thanksgiving, is an ideal time of year to replace your batteries annually.
For proper operation, smoke alarms must be kept clean and free of dust, cobwebs, etc. Never clean your smoke alarms using water,
solvents or cleaners as they may damage the unit. Be sure to follow the manufacturer's cleaning instructions at all times. Clean your
smoke alarms by gently vacuuming them using the soft brush attachment on your vacuum. Smoke alarms should be vacuumed from
the outside only; do not try to open the unit. Test your smoke alarm after cleaning to ensure it’s working. (OFM SITE - AC powered
   smoke alarms should only be vacuumed externally and no attempt should be made to open the case. Be sure to follow
   the manufacturer's instructions at all times. If specifically recommended by the manufacturer, open the battery cover
   on battery operated smoke alarms and gently vacuum the circuit board.)

Clean the exterior of the smoke alarm to remove dirt and grease following the manufacturer’s instructions. Most manufacturers suggest
using a damp cloth only.
Never paint a smoke alarm. Paint can seal the vents and interfere with the sensor’s ability to detect smoke, hampering its proper operation.
Replace smoke alarms if they fail to operate properly when tested.
Replace smoke alarms every 10 years from the date of manufacture. The date of manufacture is noted on the smoke alarm.

Disposal of Expired Smoke Alarms

Residential ionization smoke alarms contain an extremely small amount of radioactive material, americium 241 (33 kilobecquerel – kBq). This is comparable to the background radiation already present in many materials.

The Canadian Nuclear Safety Commission has confirmed that individual smoke alarms containing americium 241 may be disposed of in the regular garbage. However, if the smoke alarm contains radium or if there are large numbers of smoke alarms to be disposed of, more than 10 units, they should be shipped to the Low Level Radioactive Waste Management Office for disposal. Visit the LLRWMO website at for contact details and inquiries.

Windsor Fire & Rescue Services, Smoke Alarm Guidelines. URL:

Office of the Fire Marshal, MAKE IT STOP! Advice for dealing with nuisance alarms. URL:

Office of the Ontario Fire Marshal.

Low Level Radioactive Waste Management Office.

The Canadian Hearing Society. URL:

Safe At Home. URL:

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