Limitations of Fire Alarms
Fire Alarms have significantly helped to reduce the number of fire fatalities in countries
where they are widely installed. However independent authorities have stated that they may
be ineffective in some circumstances. There are a number of reasons for this:
• The Alarms will not work if the mains power is off and the battery back-up is depleted.
NOTE:
Constant exposure to high or low temperatures or high humidity may reduce the
life of the battery.
• Alarms will not detect fire if sufficient smoke / heat does not reach the Alarm. Smoke / Heat
may be prevented from reaching the Alarm if, for example, the fire is too far away, if the
fire is on another floor, behind a closed door, in a chimney, in a wall cavity, or if the
prevailing air draughts carry the smoke / heat away. Installing Alarms on both sides of
closed doors and installing more than one Alarm as recommended in the '
INSTALLER
SECTION
' of this booklet, significantly improves the probability of early detection. Installing
an LD1 system gives the best coverage.
• The Alarm may not be heard.
• The Alarm may not wake a person who has taken drugs or alcohol.
• Alarms may not detect every type of fire to give sufficient early warning.
• Alarms don’t last indefinitely. For example if there is a build up of contamination then the
performance of the Alarm will be impaired.
It is recommended that Alarms are replaced after 10 years as a precaution (see ‘replace by’
date on the side of the Alarm).
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