1. FIRE ALARM SYSTEM
The Basics
NFPA 72 National Fire Alarm Code® 2007
Not a Code unless adapted by AHJ
NFPA 101 Life Safety Code® 2006
Not a Code unless adapted by AHJ

2. FIRE ALARM SYSTEM
NFPA 101 Life Safety Code®2006
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
“The purpose of the code is to provide minimum
requirements, with regard to function, for the
design, operation and maintenance of buildings or
structures for safety of life from fire”
This is accomplished by:
 1.) Protection of occupants not intimate with the
Initial fire development
 2.) Improvement of the survivability of occupants intimate
with the initial fire development.

3. FIRE ALARM SYSTEM
NFPA 72
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“The purpose of this code 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.”
“The purpose of fire alarm systems shall be
primarily to provide notification of fire alarm,
supervisory, and trouble conditions; to alert the
occupants; to summon aid; and to control fire
safety functions.”

4. Audible Signaling Terminology
dB
Frequency
dBA
Ambient Noise

5. Audible Signaling Terminology
dB= Measurement of loudness
Frequency= Pitch, Bass vs High pitch squeal
Narrow Band= A small range of frequenciesusually called an octave band
dBA= Loudness measurement adjusted to
how we hear and perceive the relative
loudness of different frequencies
Ambient Noise- The normal sounds during
normal occupancy. Not temporary sounds.

6. Notification Terminology
Signaling
Arouse/Alert
Notification
Information

7. Notification-How?
Use the human
senses
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Visual- Previously
discussed
Audible
Other

8. Audible System Goals
How loud must the fire alarm be for the
given noise information?

NFPA 72.4 Audible Characteristics

9. Public Mode Audible Req.
NFPA 72.4.2.1


15dB above average ambient sound
5dB above maximum sound level of 60
seconds.

10. Private Mode Audible Req.
Private mode-Staff is part of the overall
fire protection strategy

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Minimize fire alarm
Use voice
Combine systems
Text Messaging
Eliminate audible tones and voice in some
areas

11. Sleeping Area Req.
NFPA 72.4.4.1


Public mode Requirements or
75dBA minimum
 Whichever is greater

12. Sound Attentuation
Sound is measured in dBA which is
logarithmic scale

Double distance= reduction of ½ of sound
pressure (or 6dB)

13. Design of Audible Signaling
Distance
(from device)
10’
20’
40’
80’
Sound level
(dBA)
95dB
89dB
83dB
77dB

14. Design of Audible Signaling
Using fewer appliances results in some
locations being very loud.
Using more appliances at a lower level
results in even distribution without loud
spots.

15. Next Presentation
Audible Signaling

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
Noise Coefficients (NC)
Sound Transmission Coefficients (STC)
Locating devices.
Initiation Basics
 Heat detectors