Dear Barry,

We are currently remodeling our home and would like to upgrade the smoke alarm system to comply with current fire safety standards. This may not be required for an older home, but we’d like to do it anyway. Additionally, we want to install carbon monoxide detectors. What can you tell us regarding these upgrades? – Raymond

Dear Raymond,

Retrofitting a modern smoke alarm system in an older home can become quite involved, since current standards require the interconnection of all alarms. This means that a network of wires will be needed, enabling each smoke alarm to activate the other alarms in your home. If smoke is detected by one fixture, then each component of the system should sound the alarm.

Required locations for smoke detectors in a single-family dwelling include one in each bedroom, one outside of each separate sleeping area, and at least one on each additional story of the dwelling, including basements and cellars. In most locales, alarms are not required in sub-areas and attics.

The power source for smoke alarms should include direct wiring to the primary electrical system, plus battery back-up in case of a power failure during a fire.

Although not yet a requirement in most municipalities, carbon monoxide (CO) detectors are highly recommended to prevent asphyxiation by faulty fuel-burning appliances. Some manufacturers of smoke detectors produce combination fixtures that react to smoke or carbon monoxide. But smoke detectors work best near ceilings, since smoke rises, while carbon monoxide detectors are best when located near the floor, since CO is heavier than air. Therefore, separate fixtures are advised. Accordingly, you can buy CO alarms that plug into standard wall outlets, typically located within a foot of the floor.

To ensure proper installation of your smoke alarm system, have the wiring installed by a licensed electrician. And be sure to consult your local building department regarding specific requirement that may differ from the general standards listed here.

Dear Barry,

In the middle of the night, my hard-wired smoke detector went off, sounding for about a minute, waking everyone in the house, and finally shutting off. Then in the morning, this happened twice again. What could be causing this malfunction? Is the detector simply old and in need of replacement? What do you recommend? – Herbert

Dear Herbert,

If your smoke detector is hard-wired, without battery backup, then we can rule out the possibility of a battery in need of replacement. As you suggest, the problem could be that the fixture is old and in need of replacement.

However, it is also possible that there is a small creature living in the device, a spider for example. This is a common cause of false alarms with smoke detectors. Every smoke alarm contains a small isolated chamber in which a stream of radioactive particles is projected against a specialized receptor. If any objects interrupt this transmission, such as smoke molecules or a resident arachnid, the alarm is thereby activated. Regardless of the cause, replacement of the device is recommended.

To write to Barry Stone, please visit him on the Web at


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