120 V Smoke Alarms with Low Frequency sounders
Subject: Fire Alarm Specification Update – Smoke Alarms, Combination Smoke/CO Alarms, and Low-Frequency Notification Requirements
Engineering Team,
The following information is provided to assist with updating fire alarm specifications for multifamily residential, hotel, motel, dormitory, senior living, and other Group R occupancies. Please contact me with any questions, concerns, corrections, or project-specific considerations.
Smoke Alarm Specifications
Most residential smoke alarms utilized in multifamily construction are 120 VAC devices with battery backup.
In many projects, smoke alarms are monitored through alarm relay contacts connected to fire alarm monitor modules. This approach can reduce installation costs while providing alarm supervision.
When monitored through relay contacts, smoke alarms function only as initiating devices and do not provide:
Detector sensitivity monitoring
Detector sensitivity adjustment
Detector maintenance reporting
Individual detector status information
Designers should carefully evaluate whether relay-monitored smoke alarms provide the desired level of functionality for the project.
Combination Smoke/Carbon Monoxide Alarm Considerations
Many engineers currently specify combination smoke/carbon monoxide (CO) alarms powered by 120 VAC with battery backup.
When combination smoke/CO alarms are connected to a fire alarm system, the devices should provide:
A dedicated relay output for smoke alarm activation.
A dedicated relay output for carbon monoxide activation.
Separate outputs are necessary to allow the fire alarm control panel to properly initiate:
Temporal 3 (T3) notification for smoke/fire events.
Temporal 4 (T4) notification for carbon monoxide events.
If a combination smoke/CO alarm provides only a single common relay output, the fire alarm system cannot reliably distinguish between a smoke condition and a CO condition. As a result, proper T3 and T4 notification sequences may not be achievable.
For this reason, combination smoke/CO alarms without separate relay outputs for smoke and CO should generally not be used when interfacing with a building fire alarm system.
2021 IBC Low-Frequency Sounder Requirements
IBC Section 907.5.2.1.3.2
For Group R-1 and R-2 occupancies requiring a fire alarm system under Sections 907.2.8 or 907.2.9, the audible alarm signal activated by single-station or multiple-station smoke alarms within dwelling or sleeping units must provide a 520 Hz low-frequency alarm signal. [manualslib.com]
Where compliant smoke alarms are not available or are not suitable for the application, compliance may be achieved through:
Listed 520 Hz low-frequency notification appliances, or
Smoke detectors equipped with listed integral 520 Hz low-frequency sounder bases. [manualslib.com], [kidde.com], [9123-smoke...tector.biz]
Current Product Availability
At the time of this writing, only two manufacturers are known to offer 120 VAC residential smoke alarms with integrated 520 Hz low-frequency sounders:
Gentex
PLACE Any Space
Model: PL1AS (918-0022-002) [placehomes...utions.com], [kidde.com]
Kidde
P4010LACS-W
P4010LACS-WF [buildings....eywell.com]
Designers should verify current listings and product availability before specification.
Visible Notification Considerations
A significant design limitation currently exists in the marketplace.
The residential smoke alarms identified above provide integrated 520 Hz low-frequency audible notification; however, they do not include integrated ADA-compliant visual notification appliances (strobes). [kidde.com], [buildings....eywell.com]
Likewise, residential smoke alarms that include integrated strobe lights generally do not provide listed 520 Hz low-frequency audible notification. [lifesafetycom.com]
For projects requiring both:
Low-frequency audible notification
ADA visual notification
Separate smoke and CO annunciation
System monitoring and reporting
a fire alarm system utilizing system smoke detectors, low-frequency notification appliances, and dedicated strobe devices is often the most practical and code-compliant solution.
Accessible Sleeping Accommodation Requirements
IBC Table 907.5.2.3.2 establishes the minimum number of sleeping accommodations required to be equipped with visible alarm notification.
Examples include:
Number of Sleeping UnitsRequired Units with Visible Alarms6-25226-50451-75776-1009101-15012151-20014
Designers should verify final quantities and locations based on the adopted code edition and project-specific accessibility requirements.
Accessible sleeping accommodations generally require:
Visual notification in restrooms/bathrooms.
520 Hz low-frequency audible notification within sleeping rooms.
520 Hz low-frequency audible notification within living areas that may reasonably be used for sleeping. [manualslib.com]
Fire Alarm System Smoke Detector Option
If separate smoke and CO relay outputs are not available from combination smoke/CO alarms, engineers should consider permitting the use of fire alarm system smoke detectors and CO detectors.
Advantages include:
Proper differentiation between smoke and carbon monoxide events.
Reliable activation of Temporal 3 and Temporal 4 notification patterns.
Enhanced supervision and monitoring.
Sensitivity reporting and maintenance information.
Greater programming flexibility.
Combination smoke/CO detectors that integrate directly into fire alarm systems are available from multiple manufacturers.
Addressable Smoke Detector Advantages
Addressable smoke detectors provide capabilities not available with conventional household smoke alarms, including:
Individual detector identification.
Sensitivity monitoring and reporting.
Device maintenance alerts.
Detector drift compensation.
Custom notification programming.
Addressable systems can often be configured so that:
A single detector activation affects only the dwelling unit involved.
Low-frequency sounders, horn/strobes, or strobes activate only in the affected area.
Building-wide evacuation occurs only when predetermined alarm criteria are met.
This approach can reduce unnecessary building evacuations while maintaining life safety objectives.
Addressable Notification Appliance Advantages
Addressable horn strobes and speaker strobes provide additional flexibility by allowing notification to be tailored to specific conditions.
Examples include:
Unit-only notification.
Floor notification.
Smoke event notification.
Carbon monoxide event notification.
Building-wide evacuation.
Where non-addressable notification appliances are used, similar functionality generally requires additional notification circuits, control modules, power supplies, and programming complexity.
Design Recommendation
When projects require:
520 Hz low-frequency notification,
ADA visual notification,
Separate smoke and CO annunciation,
Sensitivity monitoring,
Detector maintenance reporting,
Selective notification,
Future programming flexibility, or
Reduced nuisance evacuations,
consideration should be given to the use of a complete addressable fire alarm system utilizing:
Addressable smoke detectors,
Addressable CO detectors,
520 Hz low-frequency sounder bases,
Low-frequency horn/strobes,
Speaker strobes, and
Dedicated visual notification appliances.
At present, available residential smoke alarms with integrated 520 Hz low-frequency sounders provide limited system integration capabilities and do not currently provide an integrated solution for both low-frequency audible notification and ADA-compliant visual notification.
Thank you for your consideration. I hope this information is helpful when updating specifications and evaluating design options for future projects. Please feel free to contact me if you would like additional information or discussion regarding these requirements.
Respectfully,
Larry Love 801 898 6003 Larry.Love@jci.com
Life Safety Systems Representative
Johnson Controls Fire Protection Services, LLC.