FACP Power Supply & Battery Systems 1 — Questions and Answers
Question 1: Per NFPA 72, what is the minimum secondary (standby) power duration required for a fire alarm system in a building protected throughout by an automatic sprinkler system?
- 24 hours (Correct answer)
- 48 hours
- 12 hours
- 4 hours
Correct answer: 24 hours
NFPA 72 requires a minimum of 24 hours of standby power for sprinklered buildings, followed by 5 minutes of alarm operation.
Question 2: What battery chemistry is most commonly specified for FACP secondary power supplies?
- Nickel-cadmium (NiCd)
- Lithium-ion (Li-ion)
- Sealed lead-acid (SLA) (Correct answer)
- Alkaline
Correct answer: Sealed lead-acid (SLA)
Sealed lead-acid (SLA) batteries are the most common type used in FACPs due to their reliability, maintenance-free operation, and compatibility with continuous float charging.
Question 3: What is the standard primary AC input voltage for a commercial FACP in the United States?
- 24 VAC
- 120 VAC (Correct answer)
- 240 VAC
- 48 VAC
Correct answer: 120 VAC
Commercial FACPs in the US are powered by 120 VAC from a dedicated branch circuit on the building's electrical system.
Question 4: Per NFPA 72, how often must the secondary power supply capacity be tested on a fire alarm system?
- Monthly
- Quarterly
- Annually (Correct answer)
- Every 5 years
Correct answer: Annually
NFPA 72 requires annual testing of the secondary power supply capacity to verify it meets the minimum standby and alarm duration requirements.
Question 5: When performing battery calculations for an FACP, what derating factor is typically applied to account for battery aging?
- 0.50 (50%)
- 0.75 (75%)
- 0.80 (80%) (Correct answer)
- 0.90 (90%)
Correct answer: 0.80 (80%)
A derating factor of 0.80 is applied so that batteries are replaced before capacity falls below 80% of their rated value, ensuring reliable standby performance.
Question 6: What is the primary purpose of the dedicated circuit breaker required for an FACP?
- To allow remote shutoff during fire emergencies
- To prevent the fire alarm from sharing a circuit with other loads that could cause power interruptions (Correct answer)
- To limit current flow to smoke detectors only
- To provide overcurrent protection to battery circuits only
Correct answer: To prevent the fire alarm from sharing a circuit with other loads that could cause power interruptions
NFPA 72 requires a dedicated circuit for the FACP so that other electrical loads cannot trip the breaker and inadvertently interrupt fire alarm power.
Question 7: What label is required on the dedicated circuit breaker for a fire alarm control panel per NFPA 72 and NEC Article 760?
- 'Emergency Power Only'
- 'Fire Alarm — Do Not Turn Off' or equivalent (Correct answer)
- 'FACP Main Disconnect'
- No special label is required
Correct answer: 'Fire Alarm — Do Not Turn Off' or equivalent
NFPA 72 and NEC 760 require the FACP circuit breaker to be labeled 'Fire Alarm Circuit — Do Not Turn Off' or equivalent wording to prevent inadvertent shutoff.
FACP Power Supply & Battery Systems 1
Per NFPA 72, what is the minimum secondary (standby) power duration required for a fire alarm system in a building protected throughout by an automatic sprinkler system?