Did you know that a low frequency audible fire alarm signal is required in all sleeping areas of newly constructed hotel guest rooms and dormitory sleeping rooms? NFPA 72 has initiated a code change to the 2010 edition that will require that new sleeping areas utilize a low frequency sounder with a 520 Hz (+/- 10%) square wave. This new requirement is located in Section 18.4.5: Sleeping Area Requirements.
When is the compliance date for low frequency sounder installations?
January 1, 2014.
Will this requirement also be in effect in the 2013 edition of NFPA 72?
Yes, the requirements are still in effect in the 2013 edition of NFPA 72.
Why has this code change been implemented?
The intent of the new requirement is to improve waking effectiveness, because smoke alarms and fire alarm systems are most valuable when occupants are asleep. This observation is illustrated in a 2010 U.S. Fire Administration study, which reports that 50% of residential fire fatalities occur between 10 PM and 6 AM. And according to a 2008 Dorothy Bruck study, most unimpaired adults wake up quickly to the so-called standard audible signal, even at levels well below 75 dBA. The majority of fire alarm horns will signal with a frequency range between 2 KHz and 4 KHz. Also, integral sounders in nearly all smoke alarms produce a 3 KHz audible alarm signal.
However, how effective is that standard signal at waking up high-risk population segments such as school-age children, the elderly, and the hearing impaired? A U.S. Fire Administration study revealed that 13% of residential fire fatality victims are less than 10 years old and it’s suspected that over 27% of civilian fatalities in residential building fires are linked to alcohol, drug, or chemical influence. Additionally, more than 34.5 million people in the United States are hard of hearing.
In 2006, the NFPA petitioned two research projects from the Fire Protection Research Foundation (FPRF) to study audible fire alarm signal effectiveness in high-risk groups: Waking Effectiveness of Alarms for Adults Who Are Hard of Hearing, and Waking Effectiveness of Alarms for the Alcohol Impaired. The studies reached the following conclusions:
• The low frequency, 520 Hz signal is the most effective. It woke up 92% of hard of hearing participants when presented at or below 75 dBA for 30 seconds.
• In comparison, the standard 3 KHz signal woke up 56% at or below 75 dBA.
• The low frequency signal is superior to bed and pillow shakers and strobe lights.
Where does the code apply?
The requirement applies to new sleeping spaces. Some specific applications include:
• Retirement/Assisted living facilities
• College/University dormitories
Are the low frequency sounders required for retrofit applications?
No, the intent of the code is to require the installation of the low frequency sounders only in new buildings. Depending on the level of retrofit, if determined by the authority having jurisdiction, the building may need to comply with the new low frequency requirements.
Carbon Monoxide Detectors
In response to the changes in NFPA 72 for low frequency smoke and fire alarms in sleeping rooms, NFPA 720, The Standard for the Installation of Carbon Monoxide (CO) Detection and Warning Equipment, likewise adopted new provisions for the hard-of-hearing and profoundly deaf communities. NFPA 720: 2012 has identical provisions to those in NFPA 72: 2010 for notification appliances connected to a protected premises system. The effective compliance date is January 1, 2015.
The 2015 edition of NFPA 720 is expected to have identical provisions to those in NFPA 72: 2013. These provisions in NFPA 720 are intended to provide the same protection from CO hazards for hard-of-hearing and deaf individuals as NFPA 72 provides to these same individuals from smoke and fire.
To accommodate these code updates, fire and life safety manufacturers continue to develop innovative solutions. There are now sounders and sounder strobes that provide the required low-frequency square wave tone. Some of these new devices are dual listed for wall- or ceiling-mount installations and are compatible with systems with proprietary synchronization protocol.