NC Fire Alarm flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Accessible vs. readily accessible

Accessible means reachable without climbing over or removing obstacles. Readily accessible adds that no tool, key, or ladder is needed for examination or maintenance.

Supervisory signal

A signal indicating an abnormal condition on a system or protected equipment, such as a closed valve or low tank level, that does not indicate a fire condition.

Trouble signal

A signal indicating a fault in the fire alarm system itself, such as an open circuit, ground fault, loss of primary power, or processor failure.

Addressable vs. conventional

Conventional panels group devices into zones and identify only the zone in alarm. Addressable panels identify each device individually by address for faster locating.

NFPA 72 scope

NFPA 72 covers fire detection, notification, and signaling system design, installation, inspection, testing, and maintenance. NEC Article 760 covers wiring methods.

NC adopted codes

North Carolina adopts the NC Building Code based on the IBC and the NC Fire Prevention Code based on the IFC. Both reference NFPA 72 for fire alarm requirements.

AHJ authority

The Authority Having Jurisdiction interprets code, approves plans, and conducts inspections. The AHJ has final say when documents conflict or intent is unclear.

NFPA 72 annual testing

NFPA 72 Table 14.4.3.2 requires annual testing of most initiating devices and notification appliances, with monthly or quarterly testing for many supervisory devices.

Smoke detector spacing

Spot-type smoke detectors on smooth ceilings are spaced at 30 feet maximum, with 15 feet (half spacing) to walls, reduced for ceilings above 10 feet.

Duct detector location

Duct smoke detectors must be installed downstream of filters and at least six duct widths from bends. The sampling tube must span the duct width.

Manual pull station height

Manual fire alarm boxes must be mounted 42 to 48 inches above finished floor, within 5 feet of an exit door, and unobstructed.

Heat detector limits

Heat detectors respond to fixed temperature or rate of rise. They are not life-safety substitutes for smoke detection and have wider spacing than smoke detectors.

Audible minimum 15 dBA

Public-mode audible appliances must produce at least 15 dBA above ambient at 10 feet, or 5 dBA above ambient, whichever is greater, in the occupiable space.

520 Hz requirement

Sleeping areas require low-frequency 520 Hz square-wave audible appliances per NFPA 72 for new construction, because low frequency is more effective at waking occupants.

Strobe synchronization

Visible appliances in the same view must be synchronized. Unsynchronized strobes can trigger photosensitive seizures and do not meet NFPA 72 requirements.

NAC voltage drop

Notification appliance circuit voltage drop must be calculated so the last appliance receives its listed minimum operating voltage. Use the two-wire voltage drop formula.

Secondary power 24h+5min

NFPA 72 requires secondary power for 24 hours of standby followed by 5 minutes of alarm for most systems, and 15 minutes of alarm for voice systems.

Battery sizing formula

Amp-hours equal standby current times standby hours plus alarm current times alarm hours, multiplied by 1.2 for aging. This determines the required battery capacity.

Battery recharge 80%

The battery charger must restore the battery to 80 percent capacity within 24 hours, or per the manufacturer's listing, to ensure readiness for the next outage.

Class A vs. Class B

Class A circuits survive a single open because they have redundant paths. Class B circuits are supervised but fail on a single open.

Sensitivity testing

Smoke detector sensitivity must be tested within one year of installation and every two years thereafter. Detectors outside the listed range must be recalibrated or replaced.

ITM records

Inspection, testing, and maintenance records must document date, device, test performed, result, and tester, and must be available to the AHJ.

Acceptance testing

Before a system is placed in service, 100 percent of devices must be tested per NFPA 72 Chapter 14, and the results documented for the AHJ.

Waterflow switch test

Open the inspector's test valve and verify the alarm activates within 90 seconds for most listed waterflow devices. Test annually.

FPL cable ratings

Fire alarm cable must be listed FPL, FPLR, or FPLP. Plenum-rated FPLP is required in environmental air spaces per NEC Article 760.

Power-limited separation

Power-limited fire alarm circuits must be separated from non-power-limited circuits by at least 2 inches or a barrier per NEC Article 760.

Fire alarm circuit marking

The dedicated fire alarm branch circuit must be marked 'FIRE ALARM CIRCUIT' and connected ahead of the main disconnect per NFPA 72.

Buried junction boxes

Junction boxes and enclosures must remain accessible and cannot be buried in walls or ceilings. This applies to all fire alarm circuit connections.

Voltage drop formula

Vd equals 2 times length times current times resistance per 1000 feet divided by 1000. Use one-way length in feet for two-wire circuits.

Strobe candela selection

Candela rating depends on room size and mounting height per NFPA 72 Chapter 18 charts, ranging from 15 cd for small rooms to 177 cd for large areas.

Record of completion

NFPA 72 requires the installing contractor to provide a record of completion and as-built documentation to the owner at system turnover.

NC contractor licensing

Fire alarm contractors in North Carolina must hold the appropriate license, pull permits before work, and schedule AHJ inspections. Unlicensed work is a violation.