7. LIMITATIONS OF SMOKE ALARMS
WARNING: PLEASE READ CAREFULLY AND THOROUGHLY
• NFPA 72 states: Life safety from fire in residential occupancies is based primari-
ly on early notification to occupants of the need to escape, followed by the
appropriate egress actions by those occupants. Fire warning systems for
dwelling units are capable of protecting about half of the occupants in poten-
tially fatal fires. Victims are often intimate with the fire, too old or 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 are neces-
sary.
• Smoke alarms are devices that can provide early warning of possible fires at a
reasonable cost; however, alarms have sensing limitations. Ionization sensing
alarms may detect invisible fire particles (associated with fast flaming fires)
sooner than photoelectric alarms. Photoelectric sensing alarms may detect visi-
ble fire particles (associated with slow smoldering fires) sooner than ionization
alarms. Home fires develop in different ways and are often unpredictable. For
maximum protection, Kidde recommends that both Ionization and
Photoelectric alarms be installed.
• A battery powered alarm must have a battery of the specified type, in good
condition and installed properly.
• A.C. powered alarms will not operate if the A.C. 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 chimneys, walls, on
roofs, on the other side of a closed door or on a different floor.
• If the alarm is located outside the bedroom 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.
