UPDATED July 1, 2020:

Smoke Alarm Program

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Smoke Detective

Hey there!  I'm a smoke alarm and I want to inform you on
the importance of installing me in your home.  It's a
dangerous place out there and I want to keep you as safe as
possible by notifying you if your home was to catch on fire!
I know you have many questions so I have compiled a few
and answered them for you.  If I haven't answered a question
please feel free to call my friends at the Williamsburg Fire
Department.  You can reach them at (757) 220-6220.


Why do I need a smoke alarm? How do they work?
Where in my home should I install them? What powers a smoke alarm?
How much do they cost? Where can I purchase them?
Are they designed for the hearing impaired? What is a carbon monoxide detector?


Why do I need a smoke alarm?
According to the United States Fire Administration, approximately 2,600 Americans die in home fires every year. Over half of these deaths (52%) occur between the hours of 10:00pm and 7:00am, when residents are typically sleeping. Smoke and toxic gases from a home fire are as deadly as heat and flames. Just two or three breaths of toxic smoke can render you unconscious. The majority of fire victims die or are injured from exposure to smoke and toxic gases, such as carbon monoxide, not actual burns. In addition, smoke obscures vision, decreasing your ability to escape.

Smoke alarms save lives, prevent injuries, and minimize property damage by detecting fires early and alerting residents, allowing crucial time to escape. The risk of dying from a fire in a home without working smoke alarms is twice as high as in a home that has working smoke alarms.


How do they work?
Smoke alarms are designed to detect the presence of smoke as it passes through the device.  Once smoke is detected the alarm will sound.  There are many types of alarms, but they are generally broken up into two categories:  Photoelectric and Ionization.

  • Photoelectric:  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.
  • Ionization:  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, thus reducing the flow of current and activating the alarm.

Both types of alarms have their strengths, and it is up to you to decide which type of alarm you prefer.  To make the decision easy, alarm manufacturers have created dual sensor smoke alarms that have photoelectric and ionization detecting capabilities.  The United States Fire Administration recommends that every residence and place where people sleep be equipped with:

  • Both ionization AND photoelectric smoke alarms
  • Dual sensor smoke alarms

After you have decided on what type of alarm you would like, there are a variety of sounding mechanisms to choose from.  Some devices simply loudly beep, while others will talk to you and direct you to evacuate.  If you are hearing impaired, manufacturers have designed detectors that use strobe lights and/or vibrate in order to alert the occupant.  Smoke alarm technology has come a long way and there are many alarms on the market today to suit the needs of every customer.


Where in my home should I install them?
smoke alarms
Install smoke alarms on every level of your home, including the basement. Many fatal fires begin late at night or early in the morning, so the U.S. Fire Administration recommends installing smoke alarms both inside and outside of sleeping areas.

Since smoke and many deadly gases rise, installing your smoke alarms at the proper level will provide you with the earliest warning possible. Always follow the manufacturer’s installation instructions.


What powers a smoke alarm?
There are two types of power sources for smoke alarms: 

  • Battery:  Battery powered smoke alarms run on either a disposable 9-volt battery or a non-replaceable 10-year lithium (“long-life”) battery.
  • Hard-Wired:  Hard-wired smoke alarms are connected into the home's electrical system.  A battery back-up is in place in case of power failure and may need to be replaced periodically.

Smoke alarms should be tested once a month by pressing the test button located on the device.  Batteries should be replaced once a year (except for lithium batteries)....for safe practices, change your batteries every time you change your clocks!



How much do they cost?  Where can I purchase them?
Smoke alarms are fairly inexpensive and reasonably priced.  Ionization and photoelectric smoke alarms cost between $6 and $20. Dual sensor smoke alarms cost between $24 and $40. Hardware stores and most department stores sell smoke alarms.  You can also purchase them online.  If you are unsure of what type of alarm to purchase, please feel free to contact us at 220-6220 and we will point you in the right direction.  Don't cheat yourself out of an important life saving tool....get one today!!



The Williamsburg Fire Department will install, at no cost, free ionization smoke alarms for City homeowners upon request.


For more information about our Smoke Alarm Program contact us at (757) 220-6220.


Visit the National Fire Protection (NFPA) website for more information on Smoke Alarms!