Consider the secondary power supply for a fire alarm system. The secondary power supply shall have sufficient capacity to operate the system under quiescent load for a minimum of how long?

Consider the secondary power supply for a fire alarm system. The secondary power supply shall have sufficient capacity to operate the system under quiescent load for a minimum of how long?

• A. 24 hours
• B. 5 minutes
• C. 15 minutes
• D. 12 hours

Answer: (A)

The important idea is how long the backup power must keep the fire alarm system alive when the main power is out. The secondary power supply needs to sustain the system at its normal, idle (quiescent) current for a full day. This ensures the system remains functional and able to monitor, report, and respond while power restoration or generator support is arranged. Because the quiescent load represents the steady-state draw with no alarms active, the backup capacity is specified to cover a 24-hour period. Shorter times like a few minutes or several hours don’t meet the standard and could leave the system unpowered during a power outage.

The important idea is how long the backup power must keep the fire alarm system alive when the main power is out. The secondary power supply needs to sustain the system at its normal, idle (quiescent) current for a full day. This ensures the system remains functional and able to monitor, report, and respond while power restoration or generator support is arranged. Because the quiescent load represents the steady-state draw with no alarms active, the backup capacity is specified to cover a 24-hour period. Shorter times like a few minutes or several hours don’t meet the standard and could leave the system unpowered during a power outage.