Smoke Detector Information

Smoke alarms that are installed and maintained play a vital role in reducing fire deaths and injuries. Smoke alarms save lives. If there is a fire in your home, smoke spreads fast, and you need smoke alarms to give you time to get out. Having a working smoke alarm cuts the chances of dying in a reported fire in half.

Almost two-thirds of home fire deaths resulted from fires in homes with no smoke alarms or no working smoke alarms.

Be sure that the smoke detectors you buy carry the label of an independent testing laboratory. Several types of detectors are available. Some run on batteries, others on household current. Some detect smoke by using an "ionization" sensor, others use a "photoelectric" detection system. All approved smoke detectors will provide protection as long as they are installed and maintained properly.

There are two types of sensors: Ionization smoke detection is generally more responsive to flaming fires. Ionization-type smoke alarms have a small amount of radioactive material between two electrically charged plates, which ionizes the air and causes current to flow between the plates. When smoke enters the chamber, it disrupts the flow of ions, which reduces the flow of current and activates the alarm.

Photoelectric smoke detection is generally more responsive to fires that begin with a long period of smoldering. Photoelectric-type alarms aim a light source into a sensing chamber at an angle away from the sensor. Smoke enters the chamber, reflecting light onto the light sensor; triggering the alarm. Some new alarms are powered by sealed, long-lasting lithium batteries, others can use a 9v lithium, both types have a life of 10 years. For the best protection, buy interconnected smoke alarms for the home. When one sounds, they all sound. Make sure the model you choose is listed by UL (Underwriters Laboratory).

Every home should have a smoke detector outside each sleeping area and on every level of the home, including the basement. The National Fire Alarm Code, developed by NFPA, requires a smoke detector in each sleeping room for new construction. On floors without bedrooms, detectors should be installed in or near living areas, such as dens, living rooms, or family rooms. Be sure everyone sleeping in your home can hear your smoke detectors' alarm. If any residents are hearing-impaired or sleep with bedroom doors closed, install a detector inside the sleeping areas as well. There are special smoke detectors for the hearing-impaired; a light flashes as well as an audible alarm. For extra protection, NFPA suggests installing detectors in dining rooms, furnace rooms, utility rooms, and hallways. Smoke detectors are not recommended for kitchens, bathrooms, or garages. Cooking fumes, steam, or exhaust fumes could set off false alarms. Smoke detectors are also not recommended for attics and other unheated spaces. Humidity and temperature changes might affect a detector's operation.

 

Because smoke rises, mount detectors high on the wall or on the ceiling. Wall-mounted units should be mounted so that the top of the detector is 4 to 12 inches from the ceiling. A ceiling-mounted detector should be attached at least 4 inches from the nearest wall. In a room with a pitched ceiling, mount the detector at or near the ceiling's highest point. In stairways with no doors at the top or bottom, position smoke detectors anywhere in the path of smoke moving up the stairs. But always position smoke detectors at the bottom of closed stairways, such as those leading to the basement, because dead air trapped near the door at the top of a stairway could prevent smoke from reaching a detector located at the top. Don't install a smoke detector too near a window, door, or forced-air register where drafts could interfere with the detector's operation.

 

Most battery-powered smoke detectors and detectors that plug into wall outlets can be installed using only a drill and screwdriver by following the manufacturers' instructions. Plug-in detectors must have restraining devices so that they cannot be unplugged by accident. Detectors can also be hard-wired into the building's electrical system. Hard-wired detectors should be installed by a qualified electrician. Never connect a smoke detector to a circuit that can be turned off by a wall switch. If "nuisance alarms" persist, do not disable the detector; replace the smoke detector.