Since 2014, NFPA 72 requires that notification appliances installed in sleeping rooms provide a low frequency sounder signal. Research has shown that a low frequency 520 Hz signal is more effective at waking people with hearing loss and alcohol-impaired adults than a standard 3 kHz tone.
The 520 Hz signal must only be used in sleeping areas, not in common spaces such as hallways or lobbies.
What is a low frequency sounder?
Low frequency sounders are devices that produce a low-frequency tone in order to awaken occupants who are asleep or hard of hearing. They are required in certain types of buildings, such as hotels, motels and apartments, that need to comply with NFPA 72, the National Fire Alarm and Signaling Code.
These requirements came about because research had shown that they are six times more effective than the standard 3kHz signal when it comes to waking sleeping occupants in fire situations. They are designed to alert individuals with mild or severe hearing loss, children, people who are intoxicated and those who are on sleeping medication.
The sounders are essentially two wire devices that run on 24 volts. They feature a rotary switch for High/Low, Temp3, Temp4, and Continuous settings. They are also available with a Coded setting.
They can be powered by a Sync*Circuit module accessory that is compatible with most 24-volt rated fire alarm panels. This allows for easy installation in existing installations or when upgrading a fire alarm system to a new panel.
It is important to note that these sounders are not for use in hallways or lobby areas. In fact, they should be installed in the bedrooms of an apartment so that those in the room are awakened if the building fire alarm is activated.
One of the best ways to meet this requirement is by using a strobe in conjunction with your sounder. A strobe is an electronic device that uses a flash tube to trigger the sounder to activate.
Strobes are ideal for a wide range of applications, including hotels, universities and apartments. They offer the highest levels of visibility and are easily portable.
A strobe can be controlled by an integrated control panel or a standalone controller. It is available in a variety of styles and can be used in both new and retrofit projects.
Wheelock’s Exceder LED3 low frequency sounders are a great choice because they meet the NFPA codes for both fire signals and carbon monoxide (CO) signals in one device. They are easy to install and come in a variety of sizes and features.
How do they work?
A low frequency sounder in an apartment is a device that produces a tone at a lower frequency than standard fire alarm tones. It is designed to affixed to the wall or ceiling and can be installed in a variety of spaces, including sleeping areas.
These devices use a 520 hertz signal that has been proven to be more effective at waking people who are hard of hearing or have alcohol impairments than the more common 3 kHz tone that most alarm systems use. They are required in certain commercial and residential sleeping rooms by the 2010/2013 edition of NFPA 72.
The 520 hertz alarm signal is six times more effective at waking people with hearing loss and alcohol impairment than the standard 3 kHz alarm. This is a significant step forward for occupant safety in apartments, hotels, motels, dormitories and other places of sleeping.
According to a research project done at Victoria University of Australia, a low frequency 520 hertz signal is more effective in awakening a sleeping person than the more typical 3150 hertz signal used by most alarm systems. This is because many people who suffer from hearing loss and alcohol impairments can’t sleep through the more traditional alarm system tones.
In addition, the 520 hertz alarm signal has also been shown to be more effective at waking children who can’t sleep through the more traditional fire alarm strobes that are usually used in sleeping areas. This is important since children are more likely to be in the sleeping areas of a building when it’s burning and may not know that they have to wake up in order to get out of bed.
This research has led to a requirement in the 2013 edition of NFPA 72 for all audible appliances initiated by the building fire alarm that are provided in sleeping areas to be a low frequency 520 hertz alarm, which can save lives. However, they are required to be used only in the sleeping areas and not in other common spaces such as hallways and lobbies.
Despite these benefits, a downside of the low frequency sounder is that they draw a lot more current than standard 3 Hz mini-horns. This means that they will require more notification appliance circuits and additional remote power supplies in your building’s electrical infrastructure to keep them running. This can add up quickly if you have a large number of these sounders installed in your building.
Sounder Size
The size of a low frequency sounder in an apartment depends on the building’s design. For example, sound absorbing materials in rooms can reduce the loudness of a sounder by a considerable amount. Likewise, a sounder’s volume can be reduced by placing it near an air conditioning unit or heating system.
A low frequency sounder in a living room can be an understated design element that could make a difference when it comes to fire safety. NFPA 72 2013 A. 18.4.5.3 requires that a low frequency sounder be installed in rooms where sleeping is reasonable, such as living rooms.
There are a number of different sounder options available for these applications. One of the more popular is the SpectrAlert Advance HR-LF, which is a red two-wire 12/24 volt two-channel unit designed for wall or ceiling installation.
It also offers a high-candela strobe setting. It’s also the newest member of the L-Series family, which is designed for the most demanding and advanced commercial applications in the industry.
This strobe features a rotary switch to select the high and low settings, plus a Coded setting. It’s a great way to increase application versatility while making it easier for installers to test wiring continuity and avoid costly ground faults.
What’s more, the spectrAlert Advance HR-LF has a built-in light to help you find it in the dark! It’s also a good idea to install it in areas where guests will be most likely to hear it, such as a bathroom or hallway.
The SpectrAlert Advance P2RH-LF is another great choice for wall or ceiling installation, and it even has selectable high-candela strobe settings. Its most impressive feature, however, is its ability to generate an alarm signal from a single device.
Whether you need a small sounder or an impressive strobe, you’ll be happy to know that Eaton has something for every application. From our newest LED low frequency sounders to our latest solution, SAFEPATH, we have a range of life safety solutions that will meet all your notification appliance needs. Contact us to learn more about what we can do for you.
Sounder Type
A low frequency sounder in an apartment is a device that produces a tone at a lower frequency than standard fire alarm tones. Specifically, it produces a tone at 520 Hertz (Hz). Its purpose is to alert sleeping occupants that there is an emergency in the building.
These devices are required to meet the 2010/2013 NFPA 72 low frequency requirements for all commercial and certain residential sleeping spaces that are occupied by people with hearing loss or other special needs, including elderly, children, and those who are hard of hearing. The lower frequency is six times more effective than a 3kHz signal at waking people with hearing loss, according to research.
However, these devices are only required to be used in sleeping areas of buildings where people sleep, not in common spaces like hallways and lobbies. The 520 Hz tone is also the tone that precedes voice notifications in an emergency communication system.
The new NFPA 72 code also requires sounders that are able to produce 75 dB at the pillow level of a fire alarm evacuation signal, which is usually only achieved when a fire alarm horn is located near the bedroom. For this reason, it is recommended that any new high rise dwelling unit that has a horn in the corridor is equipped with a 520 Hz capable sounder base.
Another benefit of using a low frequency sounder is that it can help to reduce misunderstandings about what the notification sounds like. Because a low frequency sounder can produce a lower tone than a standard 3kHz sounder, it can also be easier to hear for individuals with hearing impairments and those who are alcohol impaired.
Several different types of low frequency sounders are available. They range in size and are designed to be affixed to the wall or ceiling. These devices can be installed to comply with a wide range of codes and standards.
For example, the Exceder LED3 520 Hz low frequency sounder line features both fire and carbon monoxide (CO) alarm signals with a high (177) and low (110) candela setting in a single device. They can replace facilities existing appliances and utilize the same single pair of wires currently in place, offering a simple retrofit to meet NFPA 72 and 720 sleeping room codes.
Sounder Applications
Low frequency sounders are used to awaken sleeping occupants in a hotel, motel, dormitory, apartment building or other sleeping space. These devices produce a low frequency signal on the order of 520 hertz that has been shown to be much more effective than the standard 3100 hertz alarm signal at waking people who are sleepy or hard of hearing, including school-age children and those with alcohol impairments.
The National Fire Protection Association (NFPA) 2010 changes to its NFPA 72 (National Fire Alarm and Signaling Code) require that new and retrofitted sleeping areas have low-frequency notification appliances in addition to the traditional fire alarm system alarms. This requirement is part of Chapter 18, Notification Appliances, and Part 29, Single- and Multiple-Station Alarms and Household Signaling Systems.
This change in requirements is based on a research project by Dorothy Bruck, Ph.D., at Victoria University of Australia, which found that a lower frequency alarm signal was more effective than the standard 3100 hertz signal in waking high-risk occupants. The study also discovered that people who have hearing loss are more likely to respond to this type of signal, which has the potential to save lives in the event of a fire.
NFPA 72 requires these sounders to operate within the range of 520 hertz +/-10 percent, and to be produced on a square wave tone. These low-frequency notification appliances are designed to be simple to install, easy to maintain and aesthetically pleasing.
The SpectrAlert Advance series offers the most versatile and easy-to-use line of wall-mount and ceiling-mount low frequency sounders in the industry. All units come with a variety of features to increase application versatility while simplifying installation and protecting them from construction damage.
They include field-selectable candela settings and automatic selection of 12- or 24-volt operation. They also feature a rotary switch for 520 Hz low frequency sounder tones and a universal mounting plate that installs on most junction boxes.
The Exceder LED low-frequency sounders are a simple, affordable and reliable solution to meet the new NFPA 72 (r) 2010/2013 low-frequency sounder requirements for sleeping areas. These sounders, available in indoor and ceiling-mount models, can replace existing appliances that use the same single pair of wires, offering a simple retrofit to help facilities comply with new codes.
Sounder Warranty
Having worked in the fire safety business for over 30 years, I am often surprised by the number of properties that fail to meet the most basic fire alarm system requirements. A low frequency sounder is the most important part of a smoke detector and should not be overlooked. A properly installed and maintained sounder is a surefire way to ensure the safety of residents, visitors and property owners alike. A quality sounder will provide many years of trouble free service and should be the centerpiece of any smoke detection system. The best way to keep a quality sounder in top condition is to maintain a regular maintenance schedule and replace worn out batteries on a quarterly basis. The best sounder vendors offer a variety of cost effective, easy to install and service replacement systems for every type of facility. There are many different sounder models and configurations in the market to suit any budget and the best way to find the right system is to consult with a specialist.