Introduction

A school fire alarm system is a key element of its overall fire protection features. Fire alarm systems that are properly designed, installed, operated, tested, and maintained can help save lives and limit property loss, regardless of the occupancy. The fire alarm system is generally intended to indicate and warn personnel of abnormal conditions, summon appropriate emergency responders, and control occupant features to enhance the protection of life.

Fire Codes

As a result of several well-publicized tragic fires in the 1970s and 1980s, many regulatory jurisdictions such as cities, counties, and states reviewed their building and fire codes and regulations and strengthened the protection requirements to help reduce the loss of life and property. The most prevalent fire safety codes and standards known throughout the USA are the ones developed by the National Fire Protection Association (NFPA). Many of these codes and standards are adopted by regulatory jurisdictions. Similarly, model building codes are developed by private associations for modification and adoption by the regulatory jurisdictions. Prior to 1994, there were three primary model building code organizations: Building Officials and Code Administrators (BOCA), Southern Building Code Congress International (SBCCI), and International Conference of Building Officials (ICBO). Starting in 1994, these three model building code organizations collaborated to develop a single combined organization known as the International Code Council (ICC), which over time replaced their three individual building codes into a single model building code. NFPA has also developed a model building code known as NFPA 5000, Building Construction and Safety Code. The requirements in the model building codes as it relates to fire alarm and emergency communication systems (ECSs) typically define the following components:

1. Occupancy classification

2. Location of smoke detection

3. Function of the fire alarm and ECS

4. Operation of the voice/alarm functionality of the system

5. Provision for a fire department communication system

6. Components of the fire command station

7. Power requirements for the system

8. Location of manual pull stations

9. Exit door unlocking requirements

The last two decades of fire alarm system development has overshadowed the fire alarm systems from the previous 100 years of development. Over the years, fire alarm systems have evolved from telegraph systems to signal multiplexing, from the manual ringing of a bell to automatic voice communication systems, from hardwired connections to fiber optics and wireless transmission, from unsupervised smoke detectors to addressable and analog-initiating devices that report their status, from a relay-based architecture fire alarm control units that dubbed “solid state” because of their weight and physical size to today’s microprocessor-based control units, and from fire detectors that required huge fires to actuate to smoke detectors that are capable of detecting the fire before you can either smell or see the smoke.

All of the technology developments of the fire alarm systems have influenced and contributed to the development and changes of the fire alarm codes and standards, which are used to detail the performance criteria, and establish the installation requirements, inspection, testing, and maintenance requirements of today’s fire alarm systems.

Through the evolution of fire alarm systems, systems were designed and installed to be stand-alone systems which were meant only to detect a fire and provide notification of a fire. Today’s system stretches well beyond a stand-alone fire alarm system to a combined and integrated system with the capability: to detect fires from standard conventional means of smoke, thermal, and flame detection to the latest technology using very early smoke detection technology to video detection; to monitor and control security features for a facility; to providing multiple methods of notification of a variety of emergency events using multiple technologies of notification such as voice messaging, visual notification, distributed recipient messaging such as text and email notifications, pop-up on computer screens and message monitors to notify occupants of all types of emergency events such as bomb threats, severe weather, hazardous material incidents, and fire, just to name a few.

It is important to understand the fire protection goals for the system. The fire protection goals of the system will establish the baseline for detection, notification, and operation of the system. The need and design of fire alarm systems for schools are typically driven by the requirements of the building and life safety codes; therefore, the owner’s fire protection goal may be as basic as to comply with the International Building Code (IBC) or the International Fire Code developed by the ICC or the NFPA 101, Life Safety Code. When an owner chooses to follow the prescriptive requirements for the code, this typically results in following the minimum requirements of that code as the fire protection goal. Most building codes have been developed to prevent citywide conflagrations and offer minimum occupant protection. In summary, the codes typically specify the minimum requirements to build and occupy a building. Owners or designers may want to consider other fire protection goals for facilities such as life safety, property protection, mission protection, heritage preservation, environmental protection, or multiple methods of notification.

Understanding the local code requirements is often confusing when it comes to the requirements for when a building fire alarm system is required. Typically, local and state jurisdictions adopt building and fire codes. The most prevalent building code adopted is the IBC, which is based on the occupancy classification for a facility that will determine if a fire alarm system is required, and if so, whether that system shall be automatic or manual and if detection is required. Some jurisdictions may also adopt various NFPA codes and standards. A very widely known NFPA code that will also contain requirements for when a fire alarm system is required is the NFPA 101, Life Safety Code.

NFPA 72, National Fire Alarm and Signaling Code, is the industry standard which covers the application, installation, location, performance, inspection, testing, and maintenance of fire alarm systems, supervising station alarm systems, public emergency alarm reporting systems, fire warning equipment and ECSs, and their components. The purpose of NFPA 72 is to define the means of signal initiation, transmission, notification, and annunciation; the levels of performance; and the reliability of the various types of fire alarm systems, supervising station alarm systems, public emergency alarm reporting systems, fire warning equipment, ECSs, and their components. It is important to understand that NFPA 72 does not establish the requirements for when a building is required to be provided with a fire alarm system, but basically establishes the requirements on how to design, install, and test a fire alarm system.

Local codes and NFPA 72 typically require that all equipment used in a fire alarm system be listed by an independent nationally recognized testing agency for the appropriate signaling purpose. As part of the listing and testing process, a sample of each fire alarm system component is tested to confirm its compliance with one or more of the testing laboratory’s standards. Furthermore, subsequent follow-up inspections are conducted at the manufacturer’s facilities to ensure continued compliance with the appropriate test standard for the respective component. The two most well-known testing laboratories in the USA are Underwriters Laboratories, Inc. (UL) and Factory Mutual Global Technologies (FM). Both UL and FM test fire alarm equipment and components to determine the suitability of the equipment or component for its intended service, and test for compliance with appropriate NFPA codes and standards.

Once the owner and the designer have established the fire protection goals, the fire alarm system type, application, and operation should be integrated with these goals. The type of system installed will vary depending on building occupancy, location, operations conducted in the facility, and the local or state requirements. Typically, the fire protection goals will determine the extent and the type of detection, sequence of operation, level, and method of notification and type of off-premise connection to transmit any alarm, supervisory, and trouble signals.

A fire alarm system, whether it is automatically activated by some type of detection or manually activated, will notify people inside or outside the building that some level of emergency action should be taken to respond to the condition. The system might also be designed to initiate the actuation of an automatic suppression system, such as a preaction or deluge sprinkler system, foam extinguishing system, or a clean agent suppression system.

Although there are basic requirements to all fire alarm systems, specific features of each system should include: primary and secondary power, alarm, supervisory, and trouble signals, supervision of the system and circuitry, and so on—these must be carefully considered by the designer for each fire alarm system.

The initiating devices installed as part of a fire alarm system, such as manual pull stations, smoke detectors, water flow or pressure switch, tamper switches, and so on, are connected to either the initiating device circuit (IDC) or the signaling line circuit (SLC). Generally, addressable or intelligent devices such as smoke detectors, monitor modules, and control modules are connected to the SLC, and the nonintelligent devices such as water flow and tamper switches are connected via the IDC. Notification appliances such as horns, strobes, speakers, bells, and so on, are connected to the notification appliance circuit (NAC).

NFPA 72

NFPA 72 breaks alarm systems down into three separate categories. The first is the “fire alarm system,” which consists of a system or portion of a combination system that consists of components and circuits arranged to monitor and annunciate the status of fire alarm or supervisory signal-initiating devices and to initiate the appropriate response to those signals. The second is a “supervising station alarm system,” which is a system that monitors and receives the alarm, supervisory, and trouble signals from fire alarm systems and transmits the alarm condition to the municipal communication center. The third category of the alarm system is the “public emergency alarm reporting system.” The public emergency alarm reporting system is a system of alarm-initiating devices, transmitting and receiving equipment, and communication infrastructure (other than a public telephone network) used to communicate with the municipal communications center to provide any combination of manual or auxiliary alarm service.

NFPA 72 classifies fire alarm systems into two different classifications, which are based on the type of functions they are expected to perform. The first system is a protected premises fire alarm system, which is where the entire fire alarm system operates within the protected premise, responsive to the operation of manual pull stations, water flow switch of a sprinkler system, or detection of fire by smoke or heat. This system will provide alarm and supervisory signals within a facility and produce notification signals at the facility only. The protected premises fire alarm system may also perform automatic control functions such as closing smoke dampers, releasing fire doors, de-energizing computer equipment, and shutting down heating, ventilating, and air conditioning (HVAC) systems.

The second type of system is a household fire alarm system. A household fire alarm system is a system of devices that uses a fire alarm control unit to produce an alarm signal in the household for the purpose of notifying the occupants of the presence of a fire so that they will evacuate the premises. These systems are installed primarily in residential occupants and are not permitted to be installed in schools.

Supervising station alarm systems are further defined into three different types: (1) central station (service) alarm systems, (2) remote supervising station alarm systems, and (3) proprietary supervising station alarm systems.

The central station alarm system is a system or a group of systems including the protected premises fire alarm system(s) in which the operations of circuits and devices are signaled to, recorded in, and supervised from a listed central station that has competent and experienced operators who, upon receipt of a signal, take such action as required by NFPA 72. Related activities at the protected premises, such as equipment installation, inspection, testing, maintenance, and runner service, are the responsibility of the central station or a listed alarm service local company. Central station service is controlled and operated by a person, firm, or corporation whose business is the furnishing of such contracted services or whose properties are the protected premises.

A remote supervising station is a system including the protected premises fire alarm system(s) in which the operations of circuits and devices are signaled to, recorded in, and supervised from a supervising station that has competent and experienced operators who, upon receipt of a signal, take such action as required by this NFPA 72. Related activities at the protected premises, such as equipment installation, inspection, testing, and maintenance, are the responsibility of the owner.

A proprietary supervising station alarm system is a system or a group of systems including the protected premises fire alarm system(s) in which the operations of circuits and devices are signaled to, recorded in, and supervised from a supervising station under the same ownership as the protected premises that has competent and experienced operators who, upon receipt of a signal, take such action as required by NFPA 72. Related activities at the protected premises, such as equipment installation, inspection, testing, maintenance, and runner service, are the responsibility of the owner. Proprietary supervising station service is controlled and operated by the entity whose properties are the protected premises.

In summary, the primary difference between the three different types of supervising station alarm systems is that a central station alarm system is a listed station, typically run by a for-profit company, where the operation of the system is more regulated and controlled by specific criteria than a remote supervising station or proprietary supervising station. The remote supervising station is also typically run by a for-profit company, but the operation of the system is not as controlled and regulated as that of a listed central station. The proprietary supervising station alarm system is typically under the same control as the entity whose properties are the protected premises. All three types of supervising station alarm systems have the responsibility to receive signals from fire alarm system and transmit the alarm condition to the municipal communication center.

The public emergency alarm reporting system is typically a system operated by a municipality. The most prevalent category of public emergency alarm reporting system is an auxiliary alarm system, which transmits alarm signals to a public or municipal emergency alarm reporting system to the communications center. The circuits of an auxiliary alarm system connect the alarm-initiating devices to a municipal fire alarm system. This connection is made through a transmitter, a master box, or a dedicated telephone line run directly to the municipal connection center switchboard. These types of systems are not as prevalent as they were years ago, but they still do exist in parts of the United States.

A fire alarm system has the capability of producing three different types of signals: alarm, supervisory, and trouble. An alarm signal is a signal indicating an emergency requiring immediate action initiated from automatic or manual detection of an alarm condition from a device such as a manual pull station, water flow alarm, smoke detector, or some other method of detection. A supervisory signal is a signal that results from the detection of a supervisory condition, indicating the need for action. A supervisory signaling device is a device that is not intended to create an emergency need but a supervisory device that is designed to transmit a warning of something that may affect the operation of a fire suppression system, such as an electronic tamper switch on a control valve controlling water to a sprinkler system, low water level in a water storage tank, low-temperature switch in an area monitoring a sprinkler system riser, or other similar device. A trouble signal is an audible or visual signal transmitted to warn of a trouble condition such as an open or short circuit, ground fault on a fire alarm circuit, or even the loss of AC or DC power for a fire alarm system.

Both the IBC and NFPA 101 require a manual fire alarm system to be installed for educational occupancies. The intent of a manual fire alarm system is to provide manual pull stations at the exits of the building to initiate the alarm signal. However, the IBC will require most schools constructed today to be provided with an automatic sprinkler system due to the type of construction used or the size of the building. If the school is fully sprinklered as required by NFPA 13, Standard for the Installation of Sprinkler Systems, manual pull stations are not required at every exit, as permitted by an exception in the IBC. Furthermore, smoke detection throughout the entire school is not required. Typically, smoke detectors are only required by the building or life safety codes above the fire alarm system control panels, at elevator lobbies, shaft and machine rooms (if provided), and in HVAC ductwork as required by NFPA 90A, Standard for the Installation of Air-Conditioning and Ventilating Systems, to shut down the respective HVAC unit to limit smoke from being spread throughout the entire building.

In summary, the amount or number of smoke detectors required in a fully sprinklered school is very limited. Reducing the number of smoke detectors and other detection devices with reduced installation and inspection, testing, and maintenance costs more than the life of the system. It is important to ensure that the design team includes a qualified fire protection engineer to ensure the fire protection and life safety features of the school are being provided as required by the applicable codes and standards.

Voice Systems or ECSs

Voice systems or ECSs, as previously mentioned in this chapter, are generally not required in school buildings by the model building or fire codes. Basic fire alarm systems for schools will typically only activate an alert sound such as a horn, bell, or chime using a Temporal Code-3 pattern, not a voice notification message. However, over the last couple years there have been some changes in the mind-set as to how the building fire alarm system can be used for purposes other than just notifying the occupants and fire department of a fire emergency. The current thought process is to install a system in the schools that can be used for multiple purposes such as background music, public address announcements, and for notification of other emergencies such as severe weather alerts, hazardous material incidents, and terrorist or shooter events, bomb threats, or even for fire drills. Allowing the fire alarm system to be used for these additional purposes or emergency scenarios requires the horns, bells, or chimes to be replaced with a voice system that has speakers to play prerecorded voice messages or to make live voice announcements. The industry may refer to the voice alarm system as a “mass notification system” or an “ECS” when it is used for purposes other than fire emergency notification.

As defined by NFPA 72, the purpose of an emergency voice communication system is to provide for the transmission of information and instructions pertaining to a fire or other emergencies to building occupants and the fire department. The system also allows communications with those persons remaining in the building. An emergency voice communication system can be used to partially evacuate a building in emergency conditions while permitting some building occupants to remain in safe areas.

A voice alarm system or ECS must provide a predetermined message on a selective basis to the area where the problem originated or throughout the entire facility. The alarm must also be designed as to be clearly heard and understood by all hearing-able occupants within all designated areas. The message is intended to tell the occupants what is happening and what they are to do next in response to the emergency event. Each voice message, whether it is a prerecorded message or a live message, should be clear, calm, and informative, and presented so it will motivate people into action.

There are two key components of a voice alarm system that must be achieved: (1) audibility and (2) intelligibility. Audibility is simply the loudness of the alert tone to notify the occupants of the emergency. NFPA 72 requires that an alert tone be played prior to the playing of a prerecorded voice message. The intent of the evacuation alert tone (using a Temporal Code-3 pattern) is to get everyone’s attention so that they will somewhat stop talking or making noise so they can hear and understand the voice portion of the message. For public mode of notification, the alert tone is required to be 15 decibels above the ambient background sound pressure level; however, the voice portion of the message is not required to be 15 decibels above the ambient background message. This elevated sound pressure level above the average sound pressure level is defined as the audibility of the system, which is required to be tested for each area of the building.

The intelligibility level is the capability of the message to be comprehended and understood—being “intelligible.” NFPA 72 does require that the voice system be tested to confirm that the messages are intelligible. Voice intelligibility should be measured in accordance with the guidelines in Annex A of IEC 60849, Sound Systems for Emergency Purposes. It is important that the engineer or designer of the voice system possess skills sufficient to properly design an emergency voice alarm system for the occupancy being protected. Annex D of NFPA 72 offers additional information on this subject.

There currently are two different methods of verifying or testing voice intelligibility of emergency voice alarm systems. The first is subject based, which is when the designer, owner, and authority having jurisdiction listen to the actual prerecorded messages and agree that they can be comprehended and understood. The second method commonly used in the fire protection industry is to test using an intelligibility meter. The intent is to play the STIPA test signal through the system starting at the microphone of the system and utilize an intelligibility meter in each area of the building to confirm that the system can produce an intelligible message. According to the guidance provided in Annex D of NFPA 72, the preferred intelligibility score would be 0.5 using the STI scale.

Installing an emergency voice communication system and allowing the system to be used to play background music, for public announcements, and any daily announcements is encouraged as this will make the school principal or other staff familiar with the system and make them confident to use the system during an emergency event.

In conclusion, fire alarm systems and their use have changed significantly over the last decade or two. The technology of the equipment has been enhanced, which allows the systems to be used for more than just a standard fire alarm system, thus saving costs for the school districts. It is imperative that a qualified fire protection engineer be integrated into the design process of a school to ensure the fire protection and life safety features, including the fire alarm system or the ECS of the school, are compliant with the applicable codes and standards.