7. Limitations of Smoke Alarms
WARNING: PLEASE READ CAREFULLY AND THOROUGHLY
• Fire-warning equipment for residential occupancies are capable of
protecting about half of the occupants in potentially fatal fires. Victims
are often intimate with the fire, too old or too young, or physically or
mentally impaired such that they cannot escape even when warned
early enough that escape should be possible. For these people, other
strategies such as protection-in-place or assisted escape or rescue
would be necessary.
• Smoke alarms are devices that can provide early warning of possible
fires at a reasonable cost; however, alarms have sensing limitations.
Ionisation sensing alarms may detect invisible fire particles (associated
with fast flaming fires) sooner than photoelectric alarms. Photoelectric
sensing alarms may detect visible fire particles (associated with slow
smoldering fires) sooner than ionisation alarms. Home fires develop in
different ways and are often unpredictable. For maximum protection,
the manufacturer recommends that both Ionisation and Photoelectric
alarms be installed.
• A battery powered alarm must have a battery of the specified type, in
good condition and installed properly.
• AC powered alarms (without battery backup) will not operate if the
AC power has been cut off, such as by an electrical fire or an open
fuse.
• Smoke alarms must be tested regularly to make sure the batteries and
the alarm circuits are in good operating condition.
• Smoke alarms cannot provide an alarm if smoke does not reach the
alarm. Therefore, smoke alarms may not sense fires starting in chim-
neys, walls, on roofs, on the other side of a closed door or on a differ-
ent floor.
• If the alarm is located outside the sleeping room or on a different
floor, it may not wake up a sound sleeper.
• The use of alcohol or drugs may also impair one’s ability to hear the
smoke alarm. For maximum protection, a smoke alarm should be
installed in each sleeping area on every level of a home.
• Although smoke alarms can help save lives by providing an early
warning of a fire, they are not a substitute for an insurance policy.
Home owners and renters should have adequate insurance to protect
their lives and property.
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