What Could Cause a Wired Smoke Alarm to Go Off?

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There are several reasons that a smoke alarm goes off.
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Wired smoke alarms are integrated into a building's electrical system, which means they will go off for different reasons than battery-operated smoke alarms do. Problems with the house's electrical system can be one cause a hardwired smoke detector false alarm. Smoke alarms can be connected together, adding greater protection to the occupants of the building, but introducing the potential for errors that can cause the alarm to sound.


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A hardwired smoke alarm could go off because of a dead backup battery, power surges, improper installation, dust in the air or humidity.

Chirping Smoke Alarm Sound

Many wired smoke alarms will chirp or beep in short bursts periodically and a low battery will trigger regular chirping until the batteries are replaced. Even though the alarm is hardwired, it also uses a battery backup to avoid the alarm not working properly when the building's electricity is cut off. If the batteries are not low, but the device is chirping, they may be loose inside the compartment or not installed in the right way. Dirt inside the smoke alarm, or on the alarm's grill, may also set off chirping.


Electrical Power Surges

A change in the electrical current to the wired smoke alarm will cause the smoke alarm sound to go off when there is not smoke in the air. When the electricity in the home is cut off during a storm or other event or if the electrical current spikes, the smoke alarm can go off, causing a false alarm. A loose wire in the smoke detector can also cause it to go off as the electrical current is cut off and then restored to the alarm.


Improper Alarm Installation

Proper smoke alarm installation can prevent your system from going off when it shouldn't. The interconnect wire, which is usually colored orange, is for connecting smoke alarms together. When one alarm goes off, the other connected alarms will go off as well. Connecting smoke alarms together helps alert people of a fire in large buildings where a person may not hear a fire alarm going off in a far-flung area, or in houses where people sleep with their bedroom doors closed, blocking out the noise of a smoke alarm in another part of the house.


Grounding the interconnect wire will cause the alarm to chirp every five seconds until the problem is corrected. Connecting a series of smoke alarms with an incompatible device, including some smoke alarms, will also cause the alarms to chirp. Consult the directions that came with your alarms for a list of compatible devices.


Dust-Covered HVAC Systems

Your furnace can set off wired smoke alarms when there is no fire, especially when you first turn on the furnace when the weather starts to turn cold. The oil that coats the different parts of the furnace, which is applied by the factory, can burn off when the furnace first fires up for the season, creating some smoke that blows out of the vents in the house. This smoke will set off the alarm.


Also, during the warmer months, dust and other debris will settle in the furnace, the heat ducts and on the vents in the house. When the furnace first turns on, the dust will kick up, triggering the alarm as the dust enters the sensor area.

The Alarm's Location

Smoke alarms should not be installed in areas where false alarms are likely, such as near a cooking surface, since smoke likely will be created without a fire. Smoke alarms should also not be wired into the garage or an unfinished area of the house since dust and other debris present in the air will trigger the alarm. Fire alarms need to be located away from high-humidity areas like bathrooms and laundry rooms. The combination of humidity and smoke alarms can cause false alarms.