I receive questions and stories about installer experiences with code-compliant fire alarm systems in the field, many relating to issues about the use, application and installation requirements of visible and audible notification appliances. The most frequently asked question is: “When a fire alarm system operates to signal an ‘alarm,’ should the visible notification appliances (strobes) remain flashing when someone silences the audible notification appliances?”


This one is easy to answer but still difficult to get the authorities having jurisdiction (AHJs) to accept. NFPA 72 2013, National Fire Alarm and Signaling Code, requires the following in 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, when “silencing” the alarm signal, both audible and visible notification appliances must cease operation. The annex material reinforces the requirement, stating: “It is the intent that both visual and audible appliances are shut off when the notification appliance silence feature is activated on the fire alarm control unit. Per the ADA [Americans with Disabilities Act], it is important not to provide conflicting signals for the hearing or visually impaired.”


On the surface, you might think that requirement offers a pretty straightforward indication of how the silencing function should operate. Sadly, many AHJs have either not read this section or don’t understand it.


We receive complaints from contractors that some people in the fire service think the strobes should remain flashing while they investigate the cause of the alarm. For those who may not know, when the fire service responds to an alarm or a fire in the building, they become the sole entity in charge of that building. In some jurisdictions, statutes actually indicate the fire service takes ownership of the building until they release the building back into the care of the owner. Thus, they can leave the alarm signals operating while they investigate.


However, the fire service does not want to expend effort to keep occupants out of the building. And, they want to use their radios without the interference that the operating audible notification appliances would cause. The fire service assumes that, if someone walks into a building where the visible notification appliances remain flashing, that person will know a fire alarm has occurred and will turn around and leave the building. Unfortunately, therein lies the problem.


The general populace does not know that, when they see a strobe flashing in a building and do not hear a horn or other audible notification appliance sounding, they should not enter the building because an investigation of a possible fire is underway. Most people ignore the flashing strobes and go about their business. So, leaving the strobes flashing creates confusion.


As usual, the code means exactly what it states. When someone silences an alarm signal, all fire alarm notification appliances—audible and visible—must cease operation. Mark this section in the code so you can respond to an AHJ’s objection. I have no doubt you will continue to run into this anomaly in the field.


Another question that frequently arises: First of all, as I have said many times before, NFPA 72 does not require a building owner to install a fire alarm system. However, when some other code or law requires a fire alarm system installation, NFPA 72 has all of the application, design, installation, testing and maintenance requirements for a fire alarm system, its devices, and its appliances (see Life Safety Systems, page 64).


Often, the model fire code adopted in a jurisdiction has some requirements for where an owner must install a fire alarm system. Such requirements will specify the type of notification appliances required, including where to locate any visible notifications appliances. In all jurisdictions, a building owner must follow the ADA and the ADA Accessibility Guidelines (ADAAG). Generally, all building and fire codes intend to align with the ADA and ADAAG requirements. The ADA states in Section 702.1:“Fire alarm systems shall have permanently installed audible and visible alarms complying with NFPA 72.”


An exception states: “Fire alarm systems in medical care facilities shall be permitted to be provided in accordance with industry practice.”


However, Section 215.2 of the act—covering public and common use areas—contains the requirements for where a building owner must provide alarms and states the following: “Alarms in public use areas and common use areas shall comply with 702.”


For employee work areas, Section 215.3 states: “Where employee work areas have audible alarm coverage, the wiring system shall be designed so that visible alarms complying with 702 can be integrated into the alarm system.”


It would appear that, when an office has an audible fire alarm appliance to allow it to meet “accessibility requirements,” the building owner should either install strobes or provide the wiring for the future addition of strobes. This requirement can confuse AHJs, too.


Recently, I received an email from a contractor who reported that an AHJ had misinterpreted this last requirement to apply to all occupiable spaces of an ambulatory medical office building. The AHJ demanded that the contractor install a strobe in all clinic procedure rooms, private offices and janitor closets. Clearly, the AHJ has offered a wrong interpretation on many levels.


Most obviously, no one stays very long in a janitor’s closet. Patients in procedure rooms tend to have staff either present or nearby. In the case of a fire alarm, the clinic’s emergency response plan would require staff to check each procedure room and assist the patients to evacuate.


Another question that I often hear: “Should all notification appliances consist of combination horn/strobes?”


No. NFPA 72 does not contain a requirement mandating the use of combination appliances. In fact, a careful review of audible and visible notification appliance requirements discloses that, in many cases, a contractor will need to use separate, independent devices to provide proper coverage throughout a building. In those rare cases where the location of an audible notification appliance and a visible notification appliance coincides, the contractor may use combination appliances.


Good practices suggest that you should first lay out the audible appliances to ensure the audibility requirements of 15 dBA above ambient sound pressure level, as measured throughout the building. Then, you should place the strobes in accordance with the requirements found in Chapter 18 of NFPA 72. Each type of appliance has differing requirements in the code. A contractor should at least initially treat each type independently when designing the notification appliance layout.


One final question for this discussion: “What should I do if the AHJ tells me the audible notification appliances—in this case horns—are too loud?”


I’m surprised an AHJ would raise this issue because I usually I hear from contractors where the building owner or occupants, not the AHJ, have complained the horns are too loud.


The sound pressure level produced by the audible notification appliances must meet the code requirement to exceed the ambient sound pressure level. In noisy spaces, such as mechanical equipment rooms, the code requires the installation of visible notification appliances wherever the ambient sound levels exceed 105 dBA. In the normal occupiable spaces in a building, NFPA 72 2013 states: “The total sound pressure level produced by combining the ambient sound pressure level with all audible notification appliances operating shall not exceed 110 dBA at the minimum hearing distance (typically 10 feet but not at the appliance).”


This level was actually reduced from the previous limit of 120 dBA to comply with Occupational Safety and Health Administration (OSHA) requirements and other laws.


As the annex of the code states: “In addition to the danger of exposure to a high sound level, long-term exposure to lower levels may also be a problem when, for example, occupants must traverse long egress paths to exit or technicians test large systems over extended time periods.”


OSHA has established a maximum permitted dose before the building owner must implement a hearing conservation program. A worker exposed to 120 dBA for 7.5 minutes per day for 40 years might be in danger of suffering a hearing impairment. The OSHA regulation includes a formula to calculate a dose for situations where a person is exposed to different sound levels for different time periods. The maximum permitted by the regulation is an 8-hour equivalent dose of 90 dBA. It is possible to calculate the dose a person experiences when traversing an egress path where the sound pressure level varies as he or she passes close to, then away from, audible appliances.


Suffice it to say, the output from a properly designed audible appliance network in a building should never rise to the OSHA extremes. And as a side note, when the alarm sounds, instead of complaining about the loudness of the alarm signal, people should leave the building or move to a designated area of refuge. Additionally, if the audible notification appliance layout is designed properly, this issue should not occur.


As you approach the commercial, industrial and institutional market, keep these common notification appliance issues in mind. Hopefully, this will help avoid problems associated with the failure of acceptance tests or with disgruntled or misinformed customers and AHJs.


As a professional contractor, you must not only know the code, you must prepare yourself for all issues that may affect your installations.