What is the maximum number of supervisory devices allowed on a single initiating device circuit?

What is the maximum number of supervisory devices allowed on a single initiating device circuit?

• A. 10
• B. 30
• C. 5
• D. 20

Answer: (D)

On a single initiating device circuit, the number of supervisory devices is limited to keep the circuit within the fire alarm panel’s ability to supervise reliably. Supervisory devices are components that indicate a condition requiring attention (like a valve or a monitored status) rather than an immediate alarm. Each device draws current and presents a circuit impedance that the panel must monitor to distinguish normal, supervisory, and alarm states. If there are too many supervisory devices on one circuit, the total current and impedance can exceed what the panel and wiring can handle, risking unreliable signaling or missed events. The standard cap for this scenario is twenty supervisory devices per initiating circuit, so the panel can reliably supervise all devices on that path. If more devices are needed, they should be distributed across additional initiating circuits.

On a single initiating device circuit, the number of supervisory devices is limited to keep the circuit within the fire alarm panel’s ability to supervise reliably. Supervisory devices are components that indicate a condition requiring attention (like a valve or a monitored status) rather than an immediate alarm. Each device draws current and presents a circuit impedance that the panel must monitor to distinguish normal, supervisory, and alarm states. If there are too many supervisory devices on one circuit, the total current and impedance can exceed what the panel and wiring can handle, risking unreliable signaling or missed events. The standard cap for this scenario is twenty supervisory devices per initiating circuit, so the panel can reliably supervise all devices on that path. If more devices are needed, they should be distributed across additional initiating circuits.