Wired smoke alarms are integrated into a building's electrical system, which means they will go off for different reasons than smoke detectors, which depend solely on battery power. Problems with the house's electrical system will cause false alarms, but smoke alarms can be connected together, adding greater protection to the occupants of the building.
Many wired smoke alarms will chirp in short bursts periodically at certain times. A low battery will trigger regular chirping until the batteries are replaced, helping avoid the alarm not working properly in a situation where the building's electricity is cut off. If the batteries are not low, they may be loose inside the compartment or not installed in the right orientation. Dirt inside the smoke alarm, or on the alarm's grill, will also set off a chirping.
A change in the electrical current to the wired smoke alarm will cause problems with the smoke alarm going 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.
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 an 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.
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.
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 also need to be located away from high-humidity areas like bathrooms and laundry rooms.