What is the maximum number of supervised smoke alarms that can be interconnected on a residential fire alarm system?

What is the maximum number of supervised smoke alarms that can be interconnected on a residential fire alarm system?

• A. 14
• B. 42
• C. 100
• D. 50

Answer: (B)

Interconnected residential smoke alarms share a single interconnect signaling path, and each device is supervised on that path to detect faults. Because the interconnect line must reliably carry the alarm signal to every unit and maintain supervision for all devices, there is a practical upper limit on how many alarms can be tied together on one circuit. The maximum commonly cited for a single residential system is 42 devices, which balances reliable signaling with supervision across the entire network. Exceeding this can lead to weaker signals, potential delays, or supervision issues, reducing overall system reliability. The other numbers don’t reflect the typical listing guidance for residential interconnects, so they aren’t the standard maximum.

Interconnected residential smoke alarms share a single interconnect signaling path, and each device is supervised on that path to detect faults. Because the interconnect line must reliably carry the alarm signal to every unit and maintain supervision for all devices, there is a practical upper limit on how many alarms can be tied together on one circuit. The maximum commonly cited for a single residential system is 42 devices, which balances reliable signaling with supervision across the entire network. Exceeding this can lead to weaker signals, potential delays, or supervision issues, reducing overall system reliability. The other numbers don’t reflect the typical listing guidance for residential interconnects, so they aren’t the standard maximum.