FST Fire Alarm Systems 4

Question 1

What condition causes a 'common cause' failure concern when all detectors on a single initiating device circuit share the same pathway?

Accepted Answer

A single fault disabling all devices on that circuit

Answer

A common cause failure occurs when one event (such as wire damage) can disable multiple devices simultaneously, undermining system reliability.

Question 2

Per NFPA 72, voice evacuation messages in high-rise buildings must be intelligible at what minimum speech transmission index (STI) or equivalent metric?

Accepted Answer

0.50

Answer

NFPA 72 requires emergency voice/alarm communications to achieve an STI of at least 0.45 (or CIS 0.50 equivalent) to ensure intelligible instructions during emergencies.

Question 3

A rate-of-rise heat detector will activate when:

Accepted Answer

Temperature rises more than 12–15°F per minute

Answer

Rate-of-rise heat detectors trigger when temperature increases faster than approximately 12–15°F per minute, indicating a rapidly developing fire.

Question 4

Which initiating device is MOST appropriate for a parking garage where vehicle exhaust could cause nuisance alarms from smoke detectors?

Accepted Answer

Linear heat detector

Answer

Linear heat detectors respond only to heat, making them immune to exhaust fumes and appropriate for environments where smoke detectors would generate nuisance alarms.

Question 5

Under NFPA 72, a fire alarm system at a protected premises must be inspected and tested at what minimum frequency?

Accepted Answer

Annually

Answer

NFPA 72 requires a minimum annual inspection and test of fire alarm systems, though some components (batteries, supervisory devices) require more frequent testing.

(FST) Fire Safety Technician Certification Practice Test

(FST) Fire Safety Technician Certification Practice Test

FST Fire Alarm Systems 4