NFPA 72 Definitions, Chapters 1-3, and Referenced Standards
This domain tests vocabulary precision. NFPA 72 Chapter 3 definitions feed every later chapter, and Chapter 2 tells you which outside standards the code relies on. Expect questions that turn on a single word - the signal type, the device category, or which UL standard applies.
The three signal types
- Alarm signal: indicates a fire or other emergency requiring evacuation or response.
- Supervisory signal: indicates an off-normal condition of a system or protected equipment needing action - a closed sprinkler control valve, low air pressure on a dry system, a fire pump running.
- Trouble signal: indicates a fault in the system itself - open, short, or ground on a circuit, loss of primary power, battery failure. Each must be distinct in audible characteristics, and distinguishable visually where visible appliances are used.
Definitions examiners reuse
- Fire alarm system: components and circuits arranged to monitor and annunciate the status of fire alarm or supervisory initiating devices and to initiate the appropriate response.
- Initiating device: originates transmission of a change-of-state condition - smoke detector, manual fire alarm box, waterflow switch.
- Notification appliance: bell, horn, speaker, strobe, or text display providing audible, visible, or tactile output.
- Qualified: having the knowledge, training, and experience to perform the task; used throughout Chapters 7 and 14.
- Alarm verification, pre-signal, and positive alarm sequence: features that delay or condition notification; each requires listed equipment and AHJ acceptance.
Referenced standards worth memorizing
NFPA 70 Article 760 (fire alarm wiring), NFPA 90A (duct detectors), NFPA 101 (where systems are required), UL 864 (control units), UL 268 (system smoke detectors), UL 268A (duct detectors), UL 521 (heat detectors), UL 464 (audible appliances), UL 1971 (visible appliances), UL 1481 (power supplies).
Worked example
A sprinkler control valve is chained shut and its tamper switch opens. The panel displays a supervisory condition. One trainee calls it a trouble; another calls it an alarm.
Reasoning: no fire condition exists, so it is not an alarm. The fire alarm system itself is healthy and fully supervised, so it is not a trouble. It is a supervisory signal, and that classification drives the required response: building staff must act, and retransmission follows the supervisory (not alarm) handling programmed for the site. Getting the label wrong changes the required action.
Traps
- Calling a valve tamper or fire pump run a trouble signal.
- Confusing UL 217 (household smoke alarms) with UL 268 (system smoke detectors).
- Assuming a supervisory signal triggers general evacuation.
- Using a definition from a newer edition than the one Delaware has adopted.