, Question 1
A new 12-story building uses a bidirectional amplifier (BDA) DAS. During
acceptance testing, the AHJ requires a 95% coverage reliability over 40 test
grid locations. If 37 locations pass the 95 dBm threshold, what is the most
appropriate conclusion?
A. The system passes because 37/40 exceeds the required 95%.
B. The system fails because 37/40 = 92.5%, below the 95% requirement.
C. The system passes if the three failing locations are in stairwells, which
are exempt.
D. The system passes because NFPA 1225 permits a 90% threshold for
BDA systems.
Correct Answer: B - The system fails because 37/40 = 92.5%,
below the 95% requirement.
RATIONALE
37/40 equals 92.5%, which is below the 95% reliability threshold
required by NFPA 1225 for critical areas. Option A miscalculates the
percentage; C is incorrect because stairwells are not universally
exempt and still require coverage; D misstates the standard, which
does not lower the threshold for BDA systems.
Question 2
Which NEC Article most directly governs the installation of optical fiber
cables used in a public safety DAS when routed through a plenum ceiling?
A. Article 725
B. Article 760
C. Article 770
D. Article 800
Correct Answer: C - Article 770
Page 2
, RATIONALE
Article 770 covers optical fiber cables and raceways, including
plenum-rated requirements. Article 725 addresses Class 1, 2, and 3
circuits; Article 760 covers fire alarm systems; Article 800 covers
communications circuits, not optical fiber.
Question 3
In a DAS design, a donor antenna receives a strong outdoor signal of 50 dBm,
but the BDA has a maximum input of 40 dBm. Which mitigation is most
appropriate to prevent BDA overload while maintaining coverage?
A. Increase BDA gain to compensate for the strong signal.
B. Add an attenuator between the donor antenna and the BDA.
C. Replace the donor antenna with a lower-gain model.
D. Reorient the donor antenna away from the serving site.
Correct Answer: B - Add an attenuator between the donor
antenna and the BDA.
RATIONALE
An attenuator reduces the signal to within the BDA's input range,
preventing overload and intermodulation. Increasing gain (A) would
worsen overload; a lower-gain antenna (C) may still provide excessive
signal; reorienting (D) is imprecise and may degrade donor signal
quality.
Question 4
A fire alarm system and a public safety DAS share a common pathway in a
building. Under NFPA 1225, which requirement applies to the pathway
survivability of the DAS?
A. The DAS pathway must meet Level 2 survivability if the fire alarm
pathway is Level 1.
B. The DAS pathway must meet the same survivability level as the fire
Page 3
, alarm system.
C. The DAS pathway must meet Level 3 survivability regardless of the
fire alarm level.
D. The DAS pathway is exempt if it shares a pathway with a fire alarm
system.
Correct Answer: B - The DAS pathway must meet the same
survivability level as the fire alarm system.
RATIONALE
NFPA 1225 requires that public safety DAS pathways meet the same
survivability level as the fire alarm system when they share a pathway,
ensuring coordinated protection. Options A and C impose incorrect
levels; D incorrectly grants an exemption.
Question 5
During a grid test, a technician records a signal strength of 98 dBm in a
stairwell. The AHJ requires 95 dBm in critical areas. The stairwell is
considered a critical area. What is the correct action?
A. Document the result as a pass because stairwells have a 100 dBm
threshold.
B. Mark the location as a failure and initiate corrective measures.
C. Average the stairwell reading with adjacent corridor readings to meet
the threshold.
D. Re-test with a different antenna orientation until a pass is obtained.
Correct Answer: B - Mark the location as a failure and initiate
corrective measures.
RATIONALE
The reading is below the required 95 dBm threshold for critical areas,
so it must be recorded as a failure and corrected. Option A invents a
different threshold; C is improper averaging; D suggests manipulating
the test rather than fixing the system.
Page 4
A new 12-story building uses a bidirectional amplifier (BDA) DAS. During
acceptance testing, the AHJ requires a 95% coverage reliability over 40 test
grid locations. If 37 locations pass the 95 dBm threshold, what is the most
appropriate conclusion?
A. The system passes because 37/40 exceeds the required 95%.
B. The system fails because 37/40 = 92.5%, below the 95% requirement.
C. The system passes if the three failing locations are in stairwells, which
are exempt.
D. The system passes because NFPA 1225 permits a 90% threshold for
BDA systems.
Correct Answer: B - The system fails because 37/40 = 92.5%,
below the 95% requirement.
RATIONALE
37/40 equals 92.5%, which is below the 95% reliability threshold
required by NFPA 1225 for critical areas. Option A miscalculates the
percentage; C is incorrect because stairwells are not universally
exempt and still require coverage; D misstates the standard, which
does not lower the threshold for BDA systems.
Question 2
Which NEC Article most directly governs the installation of optical fiber
cables used in a public safety DAS when routed through a plenum ceiling?
A. Article 725
B. Article 760
C. Article 770
D. Article 800
Correct Answer: C - Article 770
Page 2
, RATIONALE
Article 770 covers optical fiber cables and raceways, including
plenum-rated requirements. Article 725 addresses Class 1, 2, and 3
circuits; Article 760 covers fire alarm systems; Article 800 covers
communications circuits, not optical fiber.
Question 3
In a DAS design, a donor antenna receives a strong outdoor signal of 50 dBm,
but the BDA has a maximum input of 40 dBm. Which mitigation is most
appropriate to prevent BDA overload while maintaining coverage?
A. Increase BDA gain to compensate for the strong signal.
B. Add an attenuator between the donor antenna and the BDA.
C. Replace the donor antenna with a lower-gain model.
D. Reorient the donor antenna away from the serving site.
Correct Answer: B - Add an attenuator between the donor
antenna and the BDA.
RATIONALE
An attenuator reduces the signal to within the BDA's input range,
preventing overload and intermodulation. Increasing gain (A) would
worsen overload; a lower-gain antenna (C) may still provide excessive
signal; reorienting (D) is imprecise and may degrade donor signal
quality.
Question 4
A fire alarm system and a public safety DAS share a common pathway in a
building. Under NFPA 1225, which requirement applies to the pathway
survivability of the DAS?
A. The DAS pathway must meet Level 2 survivability if the fire alarm
pathway is Level 1.
B. The DAS pathway must meet the same survivability level as the fire
Page 3
, alarm system.
C. The DAS pathway must meet Level 3 survivability regardless of the
fire alarm level.
D. The DAS pathway is exempt if it shares a pathway with a fire alarm
system.
Correct Answer: B - The DAS pathway must meet the same
survivability level as the fire alarm system.
RATIONALE
NFPA 1225 requires that public safety DAS pathways meet the same
survivability level as the fire alarm system when they share a pathway,
ensuring coordinated protection. Options A and C impose incorrect
levels; D incorrectly grants an exemption.
Question 5
During a grid test, a technician records a signal strength of 98 dBm in a
stairwell. The AHJ requires 95 dBm in critical areas. The stairwell is
considered a critical area. What is the correct action?
A. Document the result as a pass because stairwells have a 100 dBm
threshold.
B. Mark the location as a failure and initiate corrective measures.
C. Average the stairwell reading with adjacent corridor readings to meet
the threshold.
D. Re-test with a different antenna orientation until a pass is obtained.
Correct Answer: B - Mark the location as a failure and initiate
corrective measures.
RATIONALE
The reading is below the required 95 dBm threshold for critical areas,
so it must be recorded as a failure and corrected. Option A invents a
different threshold; C is improper averaging; D suggests manipulating
the test rather than fixing the system.
Page 4
