Issue 61: A Summary Comparison of Fire Alarm System Requirements in the United States and United Kingdom
By James R. Lugar, P.E.
Fire alarm systems are all designed and installed with the same basic
objective in mind: detect a fire, effectively alert and provide
information to occupants, and signal and provide information to first
responders. Exactly how these goals are met depends on the specific
conditions of each scenario – and the codes in the region of the world
In the United States, NFPA 721 is a consensus based code
and describes how to design, install, inspect, test, and maintain a fire
alarm system, while the adopted building code identifies when and where
fire alarm systems are required, and to what level. This article
considers the 2010 edition of NFPA 72 and the 2012 edition of the International Building Code® (IBC).2
In Europe, the Comité Européen de Normalisation (CEN) develops
European standards known as ‘EN’ that are adopted as national standards
in the 33 member countries. Each member country has a standards body
that publishes the EN standards with modification in addition to
standards for the specific nation, such as the British Standards
Institution (BSI). This article considers the British Standard (BS)
version of EN 54,3Fire Detection and Alarm Systems and BS 5839,4Fire Detection and Alarm Systems for Buildings, which provides specific guidance and recommendations for the design and installation of fire alarm systems.
Building Code Discussion
The model building codes that are generally applicable in North
America and Europe differ in that North American codes tend to provide
prescriptive solutions that favor active fire suppression while European
codes tend to provide performance requirements that favor passive fire
With respect to means of warning and escape, The Building Regulations
for England and Wales states in part that, "The building shall be
designed and constructed so that there are appropriate provisions for
the early warning of fire.” BS 5839 provides recommendations and
performance criteria for the design and installation of fire alarm
systems to meet this objective while BS EN 54 provides the minimum
requirements for fire alarm system performance and associated testing
In contrast, the Intent of the IBC includes a statement that, "The
purpose of this code is to establish the minimum requirements to
safeguard the public health, safety, and general welfare,” through a
variety of factors including "safety to life from fire and other hazards
attributed to the built environment”.
NFPA 72 provides the minimum
requirements for the design and installation of a fire alarm system
while referenced standards published by other standards-making bodies
provides the minimum requirements for fire alarm system component
performance and associated testing parameters.
Control and Indicating Equipment – Fire Alarm Control Unit
BS EN 54 Part 2 provides specific requirements for the function of
fire alarm control and indicating equipment (CIE). These requirements
are related to the operation of the CIE during alarm conditions, fault
conditions, upon loss of power, and associated indications.
These requirements are similar to the fundamental requirements for
fire alarm control units (FACU) prescribed in NFPA 72. The significant
difference is that BS EN 54 Part 2 provides specific testing procedures
for the CIE, while NFPA 72 defers the specific testing procedures for
FACU to UL 864.5
Alarm Initiation and Detection Levels
BS 5839 Part 1 specifies three categories of detection system levels. These categories and their subcategories include:
BS 5839-1 Fire Detection Levels
Type L: Protection of Life
L1: Installed throughout the protected building
L2: Installed only in defined parts of the building
L3: Designed for early warning to permit all occupants to escape
L4: Installed for protection of escape routes
L5: Installed in specific areas to satisfy fire safety objectives
Type P: Property Protection
P1: Installed throughout the protected building
P2: Installed only in defined parts
Type M: Manual
Manual alarm system – no detection provided
Specific guidance exists for certain situations; however, the fire
protection engineer is often responsible for selecting the appropriate
level of protection based on the specific hazards and safety features of
an individual project.
NFPA 72 defines levels of detector coverage as total (complete)
coverage, partial or selective coverage, and nonrequired coverage. The
fire protection engineer designs to these minimum requirements, but has
flexibility to propose additional (nonrequired coverage) where warranted
or required by a performance-based design to meet or exceed the minimum
level of safety prescribed by the building code.
Alarm Initiating Devices
In both regions, the type of detection selected is generally left to
the discretion of the fire protection engineer based on the specific
hazard(s) of the protected spaces. The types and function of alarm
initiating devices are also similar across each region. The primary
difference is the emphasis on fire sprinkler protection in the North
American codes while smoke detection is more prevalent in European fire
alarm system installations. In addition, manual call points or
break-glass stations per BS EN 54 Part 11 are provided in lieu of manual
fire alarm boxes. Manual call points consist of a frangible cover that
initiates an alarm condition when broken or removed.
Alarm Notification Appliances
Audible alarm signals in European countries may consist of bells,
electronic sounders, or voice annunciation. Sounders can be utilized for
phased evacuation, in which case they are designed to provide different
alert and evacuation tones.
Voice messaging has become more prevalent in recent years, and is
often recommended in facilities where the occupants are unfamiliar with
the surroundings, in areas with high occupant loads, in fire engineered
solutions, or in areas where the risk analysis determines that live
messaging is appropriate.
Specific component requirements and performance criteria can be found
in BS EN 54. Voice alarm control and indicating equipment per BS EN 54
Part 16 will often take the form of modular, rack-mounted components in
lieu of equipment integral to the fire alarm control and indicating
BS 5839 recommends that a fire alarm system be sufficient to all
persons intended. Sound pressure levels are generally recommended to be a
minimum of 65 dBA and a maximum of 120 dBA. A reduction to 60 dBA is
applicable in certain circumstances, and a sound differential of at
least 5 dBA is only applicable in spaces with an ambient sound level
greater than 60 dBA. Sleeping areas are recommended to have a sound
pressure level of 75 dBA. The principles are similar to NFPA 72;
however, NFPA 72 typically requires a 10 dBA difference, or 5 dBA above
the maximum ambient noise, with a maximum sound pressure level of 110
Sounders can be supplemented by visual alarm signals, especially in
areas with high ambient noise levels. Visual alarm signals are not
typically recommended to be installed on their own; however, they may be
appropriate to alert staff for staff-assisted evacuations or to alert
the hearing impaired.
Providing visual alarm devices in sleeping accommodations and
sanitary accommodations satisfies a component of the disabled access and
use requirements of The Building Regulations. Red beacons are the most
common form of visual alarm devices. These beacons can be standalone
units ,or more commonly, as an integral part of a sounder, and can be
incandescent or xenon strobe type. BS 5839 recommends a minimum mounting
height of 2.1 m (83 in.), but no maximum mounting height. Beacons have
not historically had any minimum light output requirements; however, the
latest version of BS EN 54 Part 23 has introduced greater light output
In contrast, occupant notification in the US includes minimum and
maximum alarm audibility and visibility requirements to be met
throughout a protected premise. Fire alarm systems utilizing emergency
voice/alarm communications are additionally required to be intelligible,
and standardized test methods are available to evaluate the
intelligibility of a voice system.
NFPA 72 provides specific requirements for strobes to include spacing
based on the strobe intensity measured in candelas (cd), and other
prescriptive requirements such as mounting height and spacing such that
all areas are provided with a minimum illumination at any point. Visible
appliances must comply with the photometric requirements of UL 1971.6
NFPA 72, National Fire Alarm Code, National Fire Protection Association, Quincy, MA, 2010.
International Building Code, International Code Council, Washington, DC. 2012.
BS En 54, Fire Detection and Alarm Systems, British Standards Institute, London, 2011.
BS 5839, Fire Detection and Fire Alarm Systems for Buildings, British Standards Institute, London, 2011.
UL 864, Control Units and Accessories for Fire Alarm Systems, Underwriters Laboratories, Northbrook, IL, 2008.
UL 1971, Signaling Devices for the Hearing Impaired, Underwriters Laboratories, Northbrook, IL, 2002.
4th Quarter 2011 - Alarm, Trouble and Supervisory - Degrees of Conditions, Signals and Responses -- NEMA
There have been cases where signals have been ignored or missed because
of complex and confusing interface ergonomics. Proposals have been
processed for the 2013 edition of NFPA 72 that would formally define
condition, signal, and response, along with several sub-definitions. The
proposed model does not dictate any new control unit interface or means
for alerting users or occupants. However, it does define a framework
for panel designers, system designers and even for the NFPA 72 technical
committees to use as systems evolve and increase in complexity. READ MORE
3rd Quarter 2010 - Building Code Seismic Requirements for
Sprinkler Systems and Special Interface Requirements with Ceiling
Systems -- Robert E. Bachman, P. E.
Bachman describes the evolution of building code seismic requirements
over the last 20 years, and specifically the additional requirements for
sprinkler systems beyond those found in NFPA-13. He also discusses how
NFPA-13 has evolved to incorporate these requirements. READ MORE
Fall 2007 - It's Not Your Father's Fire Alarm Code Anymore -- NEMA
The National Fire Alarm Code has evolved greatly since its origination
back in the late 1800s and early 1900s. The 2007 edition has branched
out to address risks and solutions for more than just fire. This article
– part one of a two-part series – examines the evolution. Part two will
discuss how the evolution might continue during the next 10 years. READ MORE
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