Causes of a Smoke Detector Being Set off

Smoke

• Fires produce smoke, which sets off the smoke detector's alarm. Your units should go off in response to the smoke from a household fire, but cooking smoke sometimes triggers them too. Most detectors do not get triggered by cigarette smoke, but the Durham Highway Volunteer Fire Department warns that it occasionally happens if many people are smoking in the same room.

Dirt

• Smoke detectors collect dirt in their interiors, even if they look clean from the outside. Detectors near cold air returns are especially prone to dirt-related false alarms because of the dust that regularly blows out. A dirt or dust build-up eventually sets off the alarm. Prevent this by vacuuming your smoke detectors every six months, the Fire Marshall's Public Safety Council advises. Cover the detectors if you have any remodeling or other dust-generating construction work done in your home.

Insects

• Insects cause smoke detector problems if they get inside the units and block or cover the sensor area. Your unit might go off if a bug blockage develops. Vacuum out the insects, or remove them with a soft brush; then clean the detector regularly to avoid future problems.

Power Interruptions

• Hardwired smoke detectors may go off when your electricity is restored after a brief power outage, the BRK construction website warns. False alarms caused by power loss are usually short with the sound stopping within a few seconds.

Humidity

• Humidity may condense on a smoke detector's sensor and circuit board and set off the alarm, according to the Durham Highway Volunteer Fire Department. Avoid this problem by not mounting detectors near showers, laundry rooms and other potentially high humidity areas.

New Construction

• Smoke detectors in newly constructed homes may go off the first time the furnace is used even if the heat system is working correctly, according to BRK. Furnaces and ductwork naturally contain some oil residue when they are brand new as protection for their metallic surfaces. The oil temporarily generates some smoke when the system is powered up, which may trigger the detectors. Construction dust and debris can also set off the alarms if they are not cleaned out when the home is finished.