Low Frequency Sounders for Fire Alarm Evacuation

Are Low Frequency Sounders Being Enforced by your AHJ

Is your jurisdiction enforcing the new code mandated 520 Hz low frequency sounders for fire alarm audibility yet?  If so how are you tackling this new requirement?  And finally did you know that the smoke alarms within the sleeping rooms and guest units do not need to meet the 520 Hz requirement?

When did this start?

Not a lot of people are aware that this requirement was originally noted in the (2010) NFPA 72 National Fire Alarm Code section 18.4.5.3.  It states "Effective January 1, 2014, where audible appliances are provided to produce signals for sleeping areas, they shall produce a low frequency alarm signal that complies with the following:
(1) The alarm signal shall be square wave or provide equivalent awakening ability.
(2) The wave shall have a fundamental frequency of 520 Hz +/- 10 percent.

Now we fast forward to 2013.

Note that the (2013) NFPA 72 Fire Alarm and Signaling Code requirements are the same found in Section 18.4.5.3

Now lets break it down.  There are a lot of code sections so stay with me.

The Annex A of NFPA 72 (2013) section A18.4.5.3 lets us know that this section does not cover the audible requirements of single and multiple station smoke alarms and instructs us to consult chapter 29 for said requirements.

If you refer to Chapter 29 "Single and Multiple-Station Alarms and Household Fire Alarm Systems" section 29.3.6 it states the following: "All audible fire alarm signals installed shall meet the performance requirements of 18.4.3, 18.4.5.1, 18.4.5.2 and 29.3.8."  Please notice that this section does not include section 18.4.5.3. This may lead one to believe that single and multiple station smoke alarms for dwelling units do not need to meet the new 520 Hz low frequency requirements.

The key section to pay attention to here is section 29.3.8 which states "Notification appliances provided in sleeping rooms and guest rooms for those with hearing loss shall comply with 29.3.8.1 and 29.3.8.2, as applicable."

Section 29.3.8.1 "Mild to Severe Hearing Loss.  Notification appliances provided for those with mild to severe hearing loss shall comply with the following:

(1) An audible notification appliance producing a low frequency alarm signal shall be installed in the following situations:

    (a) Where required by governing laws, codes, or standards for people with hearing loss.
    (b) Where provided voluntarily for those with hearing loss.

(2) The low frequency alarm signal output shall comply with the following:

    (a) The waveform shall have a fundamental frequency of 520 Hz +/- 10 percent.
    (b) The minimum sound level at the pillow shall be 75 dba, or 15 dba above the average ambient sound level or 5 dba above the maximum sound level having a duration of at least 60 seconds, whichever is greater."

Section 29.3.8.2 "Moderately Severe to profound Hearing Loss.  Visible notification appliances in accordance with the requirements of 18.5.5.7 and tactile notification appliances in accordance with the requirements of section 18.10 shall be required for those with moderately severe to profound hearing loss in the following situations:

(1) Where required by governing laws, codes, or standards for people with hearing loss.
(2) Where provided voluntarily for those with hearing loss.

What does this mean?  

If we read section 29.3.8 very carefully you will notice the word "AND" between sleeping rooms and guest rooms for those with hearing loss.  This is telling us that the requirements of section 29.3.8.1 and 29.3.8.2 apply to ALL sleeping rooms including guest rooms for those hard of hearing.

How does this effect your design?

To this date there are no UL listed UBC smoke alarms that can produce an audible tone at 520 Hz.  In fact the only manufacture that has a UL listed 520 Hz low frequency sounder appliance is System Sensor.  This means no more mini horns in the sleeping rooms of R-1, R-2 and R-2.1 occupancies.  The only way to accomplish this is by installing a System Sensor HW-LF (low frequency sounder) or addressable smoke detector with low frequency sounder base in place of all mini horns.  This will give us the required 520 Hz in all sleeping areas during a general alarm condition.

How do we accomplish 520 Hz when the Single or multiple station smoke alarm is activated?

Since there is no such thing as a low frequency LISTED smoke alarm, I propose installing addressable system smoke detectors in all sleeping rooms and guest rooms.  On top of this an addressable control module will need to be installed for each residential unit.  The control module will then need to be wired so that it controls an individual NAC (Notification Appliance Circuit) for that particular unit.  Through programming we can activate this individual control module upon activation of any smoke detectors within the unit.  Lastly the control module for each unit will need to be mapped to activate during a general alarm condition.  This way we are activating the in room low frequency sounders via the in room smoke detectors as well as any building wide general alarm device.  This method allows us to accomplish the requirements of section 18.4.5.3 as well as 29.3.8 with listed equipment and methods.

How does this effect your final cost?

Obviously there is a lot more equipment needed to perform this requirement such as addressable system smokes and control modules.  On top of this the low frequency sounders are more expensive than mini horns.  Also note that the new low frequency sounders draw more current than mini horns which will decrease your total allowable appliances per NAC ultimately increasing the number of required remote power supplies.

This is going to be a huge adjustment for our industry which will ultimately comes with a large learning curve.  I suggest your contact your local AHJ (Authority Having Jurisdiction) and find out what their interpretations on this subject are.

Strobes Flash When Fire Alarm Silenced

End Users, AHJs (Authority Having Jurisdiction) and Technicians seem to think that fire alarm strobes are required to continue flashing when the fire alarm control unit or panel is silenced.  

FACT #1:  There is not and never has been anything in the code that requires the fire alarm visual notification appliances AKA Strobes to continue flashing once the fire alarm control panel has been silenced.   

FACT #2:  NFPA 72 2013 Section 10.13.2: “When an occupant notification alarm signal deactivation means is actuated, both audible and visible notification appliances shall be simultaneously deactivated."

So Why did we have Strobes Flashing when the Fire Alarm System has been Silenced?

From what information I have been able to gather, this function crept into the minds of installers and inspectors sometime in the 1980's. The thought of having strobes continue flashing while firefighters validated the alarm condition was a plus.  Firefighters could communicate via their radios without the loud distraction caused by the audible signal.   Lastly, individuals looking to enter a facility would see the visual appliances flashing and know not to enter due to a potential threat of a fire.

This is an argument that comes up less as time moves forward, however, some people are stuck on the ability to have strobes continue flashing during a fire alarm system silence.  Please note that while NOT required by any code or standard, this can still be required within a particular building specification or City Ordinance.

The function can be done by most manufacturers and is not hard to accomplish.  However, it does not make sense to have it enabled and that is why you will not find it in any code references.  Strobes where brought into the code for ADA adaptability.  With that said, does it make sense to leave the strobes flashing if you silence the fire alarm?

Ask yourself, "How is a deaf person affected by this feature?".

When a fire alarm system is activated, a hearing impaired individual will see the strobes flashing but NOT hear the audible tone.  Once the fire alarm panel has been silenced and the audible tone is cut off, this individual has no idea the fire department is on scene, the system as been silenced and the event is being investigated.  To this individual there is still an active evacuation scenario in place until the fire alarm panel has been reset.

Ask yourself, "How is a blind person affected by this feature?".

When a fire alarm system is activated, a visually impaired individual will NOT see the strobes flashing but will hear the audible tone.   If the fire alarm system is silenced and the audible tone is cut off, this individual will have no idea there is still a potential treat in the building.  They could potentially return to their business when in fact there is an active fire alarm investigation occurring in their close proximity.  Another point noted above was the ability for flashing strobes to notify individuals to not enter a building as it is being investigated for a fire.  If you are blind, you would not be aware the fire alarm system is activated and under investigation.  The blind individual could potentially walk right into harmful or fatal situation.  

In my mind this is why NFPA 72 2013 directly addresses this situation in section 10.13.2.  If we agree to just cut off both audible and visual signals in the event of a system silence, we are not favoring or discriminating against anyone with or without a disability.

Join our Facebook Group for up to the minute fire alarm system here.

Have you freshened up on the newer fire alarm LED strobe technology?

Pre-Wire for ADA Adaptability in R2 Occupancies

What does it mean to pre-wire for future ADA adaptability?

The 2021 International Fire Code or IFC is where we look to find out what fire alarm requirements to follow when designing systems.  Specifically Chapter 9 "Fire Protection Systems".  If we dive deeper into section 907, we are informed as to what is required for each occupancy group.

For this article, we will be reviewing the requirements for an "R-2" occupancy.  As defined in the International Building Code or IBC, an R-2 group occupancy consists of: "occupancies containing sleeping units or more than 2 dwelling units where the occupants are primarily permanent in nature, including: Apartments Houses, Boarding House with more than 16 occupants, Convents, Dormitories, Fraternities and Sororities, Hotels (non-transient), Live/Work units, Monitories, Motels (non-transient), Vacation timeshare properties."

Since this article revolves around the requirements to pre-wire for future visual alarms, we will stay away from discussing the initiating side of the code.  Full requirements for an R-2 occupancy.

International Fire Code Section 907.5.2.3.3 Pre-Wire for Group R-2

Section 907.5.2.3.3 states "In group R-2 occupancies required by section 907 to have a fire alarm systems, all dwelling units and sleeping units shall be provided with the capability to support visible alarm notification appliances in accordance with Chapter 10 of ICC A117.1.  Such capability shall be permitted to include the potential for future interconnection of the building fire alarm systems with the unit smoke alarms, replacement of audible appliances with combination audible/visible appliances. or future extension of the existing wiring from the unit smoke alarm locations to required locations for visible appliances."

This is a major upgrade in comparison to a group R-1 occupancy such as Hotels and Motels.  In these facilities, the code gives us parameters as to how many rooms with visible alarms are needed based on the total quantity of sleeping units.

"So what does all this mean?"

In basic terms all living spaces within a group R-2 occupancy must contain the necessary wires, raceways and boxes to support the ability to upgrade to audible and visual notification throughout. ADA aside, our design must provide at least 75 dB in all areas of the quest room.  On top of this, your jurisdiction may now be requiring the fire alarm occupant notification to produce a 520Hz low frequency tone in all sleeping areas.  Find out more about 520Hz requirements.

A lot of fire alarm designers are confused to the actual requirements of this code section.  To be clear, it is the intent of the code to have a fully functional low frequency audible occupant notification system that can be upgraded with visual alarms without cutting walls, adding boxes or running new conduit.  All of the necessary wire or a conduit raceway must be in place to all living spaces, sleeping rooms and bathrooms within each living space.  As stated in the paragraph above, we need a minimum of 75 dB throughout the space.  To achieve this, it's typical to have a low frequency audible appliance in each sleeping room as well as the living space.  This design makes it easy to just swap out the low frequency sounder appliance for a combination low frequency and visual appliance. Don't forget that you will need a box and wire to each restroom within the guestroom.            

ADA section 4.28 "Alarms" gives us the requirements for visual appliances within ADA compliant areas.  Pay close attention to section 4.28.4 "Auxiliary Alarms" Units and sleeping accommodations shall have visual alarms connected to the building emergency alarm system or shall have a standard 110-volt electrical receptacle into which such an alarm can be connected and a means by which a signal from the building emergency alarm system can trigger such an auxiliary alarm.  When visual alarms are in place the signal shall be visible in all areas of the unit or room. Once a group R-2 living unit is upgraded to meet ADA requirements for visual alarms, you will need a low frequency audible tone of at least 75 dB throughout as well as visual alarms in all areas of the living unit.  This includes restrooms.

Side note: NFPA 72 2022 Table 18.5.5.10.3 informs us of the candela rating required visual appliances installed in  sleeping areas.

Distance from the ceiling to the top of the visual appliance lens:
> or = to 24 inches = 110 Candela
< 24 inches = 177 Candela

This standard was put in place as smoke migrates to the ceiling in the event of a fire.  It is common sense that a more intense strobe flash would be required to shine thorough the thicker smoke found closer to the ceiling and still have the ability to awake a sleeping occupant.  This is why we are required to install a 177 candela strobe when located less than 24" from the ceiling.

Best installation method to accomplish ADA adaptability for Group R-2 occupancies.

Run a trunk run down the corridor with Notification Appliance Circuit (NAC) loops as well as a Signaling Line Circuit (SLC) pulled into a J-Box within the closet of each living unit.  It is best to pick the closet that contains the unit's breaker panel.  From this J-Box pull your notification circuit loop through all appliance locations.  In the event the room needed to become adaptable, simply splice your incoming/outgoing NAC loop through in the J-Box.  This way the notification field wiring loop within the living unit is separate from the rest of the existing building NAC circuits.  Install a single output remote power supply listed for fire within the closet and power up with a dedicated 120 AC circuit.  Use the SLC in the closet to install an addressable smoke detector and control module to protect and activate the power supply.  See the example layout below:

Now keep in mind that these audible / visual notification appliances will need to activate via general alarm, floor alarm or an alarm from within the unit itself.  To activate the notification appliances from within the living unit, you could either install addressable system smoke detectors or connect addressable mini modules to the 120 VAC UBC smoke alarms.  The detectors or modules would activate the control module connected to the power supply as well as indicate a supervisory condition on the fire alarm control unit (FACU).