Electrical shock hazard.
Isolate mains electricity supply at distribution board
Clean your alarm regularly, particularly in dusty locations.
Use the narrow nozzle attachment on your vacuum cleaner to
remove cobwebs, dust and insects from around the aperture
where the smoke enters.
To clean outer case, wipe with a damp cloth and dry thoroughly
with a lint free cloth.
In cases of extreme contamination remove unit by depressing
button on side and rotating 90° deg. anticlockwise.
Check that the openings in the sensing chamber are not clogged
by inspection through the aperture.
If they are clogged (an extremely rare occurrence) then
the unit must be replaced.
All alarms are prone to insect and dust contamination which
can cause false alarms or failure to alarm. Therefore regular
cleaning should be a priority.