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Smoke Alarms2018-11-30T11:42:41+00:00
smoke alarm

Smoke Alarm

smoke alarm

Most homeowners take Smoke and Carbon Monoxide alarms for granted but they are important pieces of safety equipment that we as real estate professionals need to be aware of. A properly installed and maintained smoke alarm one of the only things in a home that can alert a family to a fire or carbon monoxide 24 hours a day, seven days a week. Whether the occupants are asleep or awake, a working smoke or carbon monoxide alarm is constantly on alert, scanning the air for fire and smoke. Unfortunately many smoke or carbon monoxide alarms are over 10 years old, damaged or missing their batteries.

According to the National Fire Protection Association, almost two-thirds of home fire deaths resulted from fires in properties without working smoke alarms. A working smoke alarm significantly increases the occupant’s chances of surviving a deadly home fire. As real estate professionals we can make a difference by calling out old or non-functioning smoke alarms.

Smoke Alarms were first widely available in the early 1970’s and by the 1990’s were requiring them in every bedroom and the hallways of home. Out of all the systems in the home, smoke alarms have more agency oversight then any other. Here is a partial list of agencies or consumer groups:

  • U.S. Fire Administration (USFA)
  • Consumer Products Safety Commission (CPSA)
  • National Fire Protection Association (NFPA)
  • National Instituted of Standards and Technology (NIST)
  • Underwriter Labs (UL)
  • NEC
  • National Association of State Fire Marshal’s
  • International Residential Code
  • Most Building Departments

Smoke Alarm Technology

The two most commonly recognized smoke detection technologies are ionization smoke detection and photoelectric smoke detection:

  • Ionization smoke detection is generally more responsive to flaming fires.
    How they work: 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.
  • Photoelectric smoke detection is generally more responsive to fires that begin with a long period of smoldering (called “smoldering fires”).
    How they work: 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.

It cannot be stated definitively that one is better than the other in every fire situation that could arise in a residence. Because both ionization and photoelectric smoke alarms are better at detecting distinctly different, yet potentially fatal fires, and because no one can predict what type of fire might start in a home, the USFA, NFPA and Underwriter Labs recommends that every residence and place where people sleep be equipped with both ionization AND photoelectric smoke alarms, OR dual sensor smoke alarms, which contain both ionization and photoelectric smoke sensors

AC/DC and interconnected smoke alarms were introduced into the building codes starting in 1989.  AC/DC alarms still need there batteries changed on annual basis but with lithium batteries  being approved for use we are now seeing smoke alarms marketing with lifetime batteries. Lithium batteries installed in a smoke alarm will last over 10 years.  What most people don’t know is that when you test the smoke alarm it is using the batteries to power the horn. This is why during an inspection frequently after testing the smoke alarms they start chirping giving the low battery alarm.

Checking your Smoke Alarms

First and foremost look at the alarm and judge its age.  The NFPA and most manufactures recommend that any alarm over 10 years be replaced.  Most alarms start out white/beige in color and as the age they take on a yellow appearance.  If you suspect it’s greater than 10 years then it should be replaced. The sensors on smoke alarms are easily contaminated by paint, grease, etc.  If the alarm has any paint or grease on the cover I will assume the sensors been compromised and recommend replacement.

Most AC/DC alarms will have a light that indicates it operating. I look for the light before I hit the test button.  Most battery only alarms do not have indicator lights so the only way to know if its operational is to hit the test button.  Most homes built after 2000 have interconnected smoke alarms. As part of the test you should hold the test button long enough to trigger all of the other alarms.

The current NFPA requirements call for smoke alarms in each bedroom and on each level (including the basement) and in the hallways. Smoke alarms should not be installed directly outside of bathrooms or within 20 Ft. of the kitchens to reduce false alarms.  In homes with vaulted ceilings the smoke alarm should be installed near the top of the ceiling.

melted smoke alarm

Are Ionization Smoke Alarm’s Faulty?

Every few years the topic comes up that “ionization detectors are bad.” This isn’t supported by any of the research on smoke alarms. This issue started back in the 90’s when there were some smoldering fires that ionization detectors were slow to detect. Texas A+M did a study and identified some scenarios where a photoelectric alarm would go off quickly and an ionization alarm could take as much as 200% longer to sound the alarm. If you look at the single scenario there would be no argument however homes are made of many different types of materials some which will smolder and some that will burn very quickly. In fact most synthetic materials will be quickly.

The NFPA, CPSC and NIST went back and studied this issue. To paraphrase their results “the different technology alarm at different rates depending on the material burning but both would alarm and allow occupants time to escape.” The state of Ohio, Maryland, and California State Fire Marshal’s all formed independent task force’s to study this issue and came to similar conclusions. I have consolidated links below to the reports.

The NIST did note that lightweight construction and modern interior furnishing tend to burn faster (which favors the ionization alarm technology) and allow less time for occupants to escape. To ensure the occupants have the greatest amount of time to exit the structure each home should be equipped with a mix of smoke alarm technology installed to the NFPA specifications. With the costs of smoke alarms dropping it now makes sense to purchase dual sensor detectors.

Recent Research on Smoke Alarms

NFPA Task group on Ionization Vs. Photelectric Smoke Alarms

Nation Institute of Standards and Testing
An Analysis of the Performance of Smoke Alarms

Underwriters Laboratory – Smoke Alarms and Residence Fires

Ohio Smoke Alarm Advisory Task Force Report

US Fire Administration

Maryland Smoke Alarm Technology Task Force Report

California State Fire Marshals Smoke Alarm  Report

National Association of State Fire Marshal’s Smoke Alarm Guidance