NFPA Code for Fire and Smoke Alarms

Everything You Need to Know About NFPA Code for Low-Frequency Fire and Smoke Alarms

Since 2010, the National Fire Protection Association has mandated that low-frequency alarms be installed as part of the building fire alarm system, in properties where occupants have mild to severe hearing loss. In 2013, the National Fire Alarm and Signaling Code was revised to mandate low-frequency fire alarms connected to the building’s fire alarm in any sleeping areas, regardless of the hearing status of the occupants. Additionally, low-frequency alarms were required on standalone smoke alarms — not connected to a building fire alarm system — in places where the occupations have mild to severe hearing loss.

More recently, in 2021, that law expanded to mandate that alarms activated by either building fire detection systems or standalone smoke alarms must use low-frequency sounders, regardless of the hearing status or age of the occupants. The code applies to all new hotels, dormitories, apartment buildings and other places where people sleep, according to NFPA.org.

Understanding which buildings require low-frequency alarms and where they must be placed are the first aspects of security and life safety systems that installers need to understand when it comes to low-frequency fire and smoke alarms, according to experts.

“At the present time, [low-frequency alarms are required] for R-1 and R-2 spaces, including hotels, motels, dormitories, apartments and the like,” Shane Clary, vice president, codes and standards compliance at Bay Alarm, says. Bay Alarm is a security and fire alarm integrator serving California, Washington and Arizona.

The alarms must be placed in areas where people are sleeping. Obviously, this includes bedrooms, Clary points out, but can also include a living area with a sofa where a guest or resident might sleep. “It could also be a closet,” he says, “if there’s a mattress that indicates someone is sleeping in the space. You might see that in some housing units in cities.”

Importance of low-frequency requirements

That’s why it’s important for engineers, contractors and designers to know the requirements in the areas they serve and to work with the region’s fire prevention bureau, fire department or building department to ensure the plans are approved. “If you have an engineer based in Pennsylvania and he’s working on a project being built in California, but he doesn’t check the California requirements and designs the system to Pennsylvania requirements, in most cases those plans are not going to be approved,” Clary explains. Working with a company like ADI, which serves the region where the construction is taking place, can help ensure that your team designs and installs the systems to meet local code requirements. ADI can also help you specify the right equipment for any project.

Research backed low-frequency alarms

In a prior article, ADI experts point out that fire and smoke alarm technology evolves slowly and is largely driven by codes established by the NFPA. The trend toward low-frequency alarms in new and existing construction is based on a research compilation from 2008, according to a guide from Honeywell, one of the leading manufacturers of fire and smoke alarms for commercial use. The study out of Victoria University showed that a low-frequency signal of 520 Hz is six to 10 times more effective at waking people than a standard 3150 Hz alarm signal. It was also shown to be more effective than bed and pillow shakers in people with hearing loss.

While most adults wake quickly to a standard, high-frequency alarm, a 520 Hz alarm was shown to effectively wake school-age children, individuals impaired by alcohol, drugs, or other chemicals, or people with a hearing impairment, the research showed.

Why is this so important? Data from the U.S. Fire Administration prior to the introduction of low-frequency alarms revealed that 50% of fire fatalities in residential buildings took place between 10 p.m. and 6 a.m., with the majority occurring between 4 a.m. and 5 a.m., when people may be in deep sleep, according to a Healthline report on sleep stages.

“The whole purpose of low-frequency sounders is to awaken building occupants,” says Ryan Sandler, part of the Everon National Fire & Life Safety Team. Everon is a fire and life safety service provider with more than 100 offices coast to coast. “So, you know, if someone is disabled, if they have hearing loss, or they're wearing noise-canceling headphones, or they're intoxicated — anything that could inhibit the building occupant from being able to hear or understand low-frequency messages.”

Additional benefits of low-frequency alarms

Based on current legislation in most municipalities, low-frequency sounders are only required in new construction. However, Clary shares that certain jurisdictions in California, including the cities of San Diego and San Francisco, have set deadlines for when building owners will need to upgrade or update their systems to encompass low-frequency sounders. “There’s no push within a city with no requirements for a building owner to voluntarily spend $100,000 or more to put in low-frequency sounders,” Clary says.

If you are updating an older system, you’ll want to meet low-frequency requirements, as well as other fire code mandates. “I think the biggest challenge that the industry has, as a whole today, is many of the existing fire alarm systems are obsolete and no longer supported by the manufacturers due to the chip obsolescence that we saw during COVID,” Sandler says. “We’re finding that now we have to upgrade obsolete fire alarm systems, which is pushing the codes and standards. Hotel owners, hospitals, dormitories, apartments and mixed-use condos are now required to put [low-frequency] sounders in sleeping areas.”

Sandler says that upgrading older systems may also help commercial real estate owners and property managers insure the building more affordably, especially in states like California with a high risk of wildfires. “Risk insurers will look at your building as uniquely different when you provide the technology for low-frequency sounders, meaning that you’re able to communicate with all building occupants during an emergency event, whether they’re disabled, intoxicated or otherwise inhibited from hearing a traditional fire alarm, life safety evacuation message or tone,” Sandler says. “Risk insurers will take into account the upgrade of a fire and life safety system.”

Challenges to installing low-frequency alarms

Power requirements

One of the biggest challenges to installing low-frequency sounders is the additional power requirements. Generating a 520 Hz sound requires a speaker element, which draws more current than the traditional piezo element you’ll find in consumer smoke and fire alarms sold in big-box stores.

“You need power supplies, and you need to watch your voltage drop on your circuits,” Clary says. “Depending on the number of appliances you have on the circuit and the distance between each other, you could end up with multiple power supplies throughout the facility.” This can add to the project’s cost, adding equipment and labor to meet the power requirements.

Larger-gauge wire

Additionally, Clary says, low-frequency applications often require thicker, 12-gauge wire. Most residential applications use 14-gauge wire, which carries up to 15 amps of voltage. However, in higher voltage applications, the wire may experience more voltage drop over long distances. On the other hand, thicker, 12-gauge wire is more suited for higher voltage applications, since it can handle up to 20 amps and typically exhibits less resistance and less voltage drop over long distances. However, in addition to being a more costly option, it’s not always the most convenient. “If you ask any installer, it’s difficult to work with that stuff,” Clary says.

Retrofit challenges

With new construction, you can design the appliances and power supplies into the plans to ensure dedicated power at those locations, minimize wire runs and integrate systems to fit the aesthetics of the space. Retrofits are not as easy and can be more costly. Yet, as legislation progresses, these upgrades may become necessary to meet fire codes.

“It is a problem with an existing building,” Clary says, “because there may not be dedicated power there…The building owner is going to have to pay to get dedicated power to the places where those remote power supplies are to be installed.” Sandler adds, “From a construction standpoint, you're not often able to reuse existing wire, and it creates a challenge and an increased cost to bring low-frequency sounders into sleeping areas.”

Key considerations for specifying low-frequency speakers

Choosing the right equipment is important, whether you’re installing a new fire and smoke alarm system or completing a retrofit project. First of all, Sandler says, equipment should meet compliance codes. “You want to provide a code-compliant system that is tested by a Nationally Recognized Testing Laboratory (NRPL),” he says, noting that Underwriter Laboratories is one of the leading testing labs. “You want to have a product that’s UL-listed for its intended use.”

Equally important, Sandler says, is choosing a system that meets the needs of the client. “You want to be able to look for a product that meets the code minimum requirements but also provides a performance-based solution that meets the application needs of the environment,” he explains. The device should be able to produce 15 dB above ambient background levels, or at least 5 dB over the maximum sound level, for a duration of 60 seconds, or at least 75 dB, whichever is greater.

Protecting building occupants in a changing climate

Sandler emphasizes that effective fire safety systems are more important than ever. In 2022, the western United States experienced more wildfires, on average, per year, than the prior 10 years. Data from the National Interagency Fire Center, reported by Nationwide Insurance, reveals that 2022 brought 68,988 reported wildfires, compared to 58,985 in 2021. The increased threat of fire isn’t the only danger, though.

Building materials used today, including PVCs, plastics, polymers, glues and synthetics, create faster flashovers, increasing danger to building occupants and first responders. “You look at the fires that occur in buildings today, they burn hotter, faster and are more toxic,” Sandler says. “Defensible space is no longer defensible with these larger, faster-moving, hotter-burning fires. So, you need greater technology to inform building occupants earlier and faster, so that we can move people out of the facilities.”