Addressable fire alarm systems are the typical choice for new installations. The programmability gives designers and installers an astounding array of operational features. However, occupants may not understand their responsibilities or how to interpret an alarm. 


A programmable addressable fire alarm control unit (FACU) can accommodate a customer’s desire to control another system or nonfire system. The 2016 NFPA 72, National Fire Alarm and Signaling Code, allows for different signaling options when connecting certain devices. To understand the available options, consider Figure A.3.3.58, describing the Condition-Signal-Response model.


For example, a fire alarm system might monitor a supervisory condition, such as a water valve in an automatic sprinkler system. When the valve is closed, a sensing switch initiates audible and supervisory signals at the FACU, where either a supervisory signal light illuminates or a textual notification occurs. If connected off-premises, the supervisory signal is transmitted to the supervising station.


Here’s another example: some system designs provide that all duct-type smoke detectors installed to control the operation of the heating, ventilating and air conditioning (HVAC) system will initiate a supervisory signal, not sound a general alarm. Typically, duct smoke detectors do not receive proper maintenance and tend to alarm from dust in the duct entering the sensing chamber. Because a duct smoke detector intends to control the spread of smoke and not to provide early fire warning and because of potential false alarms, many designers and authorities having jurisdiction (AHJs) require the alarm from a duct smoke detector to initiate a supervisory signal at the FACU. If an off-premises monitoring station exists, a supervisory signal, instead of an alarm signal, is transmitted. 


Similarly, when the code for residential occupancies requires the installation of a minimum of single- or multiple-station smoke alarms in the sleeping areas, many designers and AHJs prefer to monitor those devices.


The 2015 International Fire Code’s Section 907.2.11.7 states: “Smoke detectors listed in accordance with UL 268 and provided as part of the building fire alarm system shall be an acceptable alternative to single- and multiple-station smoke alarms and shall comply with the following:


1. The fire alarm system shall comply with all applicable requirements in Section 907.


2. Activation of a smoke detector in a dwelling unit or sleeping unit shall initiate alarm notification in the dwelling unit or sleeping unit in accordance with Section 907.5.2.


3. Activation of a smoke detector in a dwelling unit or sleeping unit shall not [emphasis added] activate alarm notification appliances outside of the dwelling unit or sleeping unit, provided that a supervisory signal is generated and monitored in accordance with Section 907.6.6. Section 907.6.6 requires that all required fire alarm systems be monitored by an approved supervising station in accordance with NFPA 72.”


Typical household activities, such as cooking, cause false alarms. Using smoke detectors rather than alarms enables an owner to monitor the devices and ensure they are not tampered with. The owner also is better informed when a device initiates a signal. 


To accomplish this, the installer uses smoke detectors installed in a “sounder base” programmed to replicate the operation of a single-station smoke alarm within the living unit but not to sound the general fire alarm. This design ensures a false alarm in a single unit does not affect the entire building or summon the fire department. However, in a real emergency, the fire alarm system would not automatically notify the fire department nor alert building occupants outside of the unit.


However, unless properly informed otherwise, the owner and occupants will likely assume that any device in alarm calls the fire department. In fact, the supervising station will only receive a supervisory signal. They will call the owner, as normally instructed, to advise him or her of this condition. 


When a contractor chooses to have an alarm device such as a smoke detector initiate a supervisory signal, the owner is responsible for notifying the fire department when a real alarm occurs. In addition, to help prevent any miscues when the design calls for an alarm device to actuate a supervisory signal, contractors must understand the implications of the system operational design for every system they design or install.