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Wireless fire detection systems must:
Be listed for the application and maintain supervision and power requirements
Definition: Wireless components must be listed and maintain supervision, tamper, and power performance.
Multi criteria detectors combine sensors to:
Improve detection reliability and reduce non fire alarms
Definition: Using multiple sensing technologies can better discriminate fire from non fire phenomena.
For elevator lobbies, detector placement should consider:
Distance from doors and air movement
Definition: Door piston winds and air currents can move smoke; avoid dead air and drafts to ensure timely detection.
Class A initiating loops are preferred over Class B when:
Increased survivability past a single open is desired
Definition: Class A loops maintain operation beyond a single open by providing a return path.
Class B circuits require what at the end of line?
An "EOL" resistor at the last device
Definition: The end of line resistor supervises the entire run for opens and grounds.
Ground faults should:
Annunciate and be located for repair
Definition: Grounds can hide other faults; prompt indication and repair are required.
"NAC" voltage drop increases primarily with:
Higher current and longer runs
Definition: Voltage drop equals current times resistance; more load and distance increase drop.
To reduce "NAC" voltage drop, designers can:
Up size conductor or shorten runs or add supplies
Definition: Larger gauge conductors and distributed power reduce resistance and drop.
Battery sizing typically includes:
Both standby time and alarm time with connected loads
Definition: Add quiescent loads for standby and active loads for alarm to meet runtime targets.
Secondary power for non voice systems is commonly:
24 hours + 5 minutes alarm
Definition: Non voice systems provide a day of standby and five minutes of alarm operation.
Secondary power for voice systems is commonly:
24 hours + 15 minutes
Definition: Voice systems require fifteen minutes of alarm after standby to deliver messages.
Speaker amplifier capacity should be planned with:
Some headroom beyond calculated tap totals
Definition: Headroom prevents clipping and distortion.
Addressable "SLC" loops often include isolators to:
Segment short circuits so the rest of loop remains operational
Definition: Isolators localize faults and improve survivability.
Which cable type is plenum rated for fire alarm?
FPLP
Definition: FPLP is listed for use in environmental air plenums per "NEC" 760.
Mixing power limited and non power limited conductors requires:
Separation or listed barriers per code and equipment listing
Definition: Maintain separation to avoid high voltage damaging low voltage insulation.
The fire alarm control unit branch circuit should be:
Dedicated and identified, with disconnect lockable in the ON position
Definition: Dedicated, identified power reduces accidental shutoff and keeps the system available.
Trouble signals should annunciate within approximately:
200 seconds
Definition: Indicating troubles in a timely manner helps maintain system reliability.
For Class N pathways, designers should provide:
Monitored network segments with power diversity
Definition: Class N covers supervised Ethernet transport; monitor links and provide backup power.
A distribution power supply used for strobes must be:
Listed for fire alarm and supervised for fault conditions
Definition: Use listed, supervised supplies so failures report to the system.
Calculated "NAC" end of line voltage must be:
Within the appliance’s listed operating range under worst case
Definition: End devices must still receive adequate voltage to meet performance and sync.
Battery strings should be replaced:
With matched, listed type and capacity, and recorded install date
Definition: Matched, listed batteries ensure proper charging and runtime.
A common cause of false voltage drop failures in practice is:
Loose terminations and excessive series resistance
Definition: High resistance at poor connections increases voltage loss at devices.
Documentation for power calculations should include:
Device counts, taps, wire sizes, run lengths, and math steps
Definition: Clear documentation supports review, acceptance, and future service.
A supervising station is a facility that:
Receives and processes signals from protected premises and initiates response
Definition: The supervising station monitors alarm, supervisory, and trouble signals and dispatches per the service agreement.
Which transmission approach improves availability?
Dual diverse paths or an enhanced supervised single path
Definition: Redundant or enhanced supervised paths reduce the chance that a single failure blocks reporting.