What is the correct wiring configuration on a household fire alarm system initiating circuit?

What is the correct wiring configuration on a household fire alarm system initiating circuit?

• A. Series with EOL supervision
• B. Parallel with EOL supervision
• C. Series without EOL supervision
• D. Parallel without EOL supervision

Answer: (A)

The initiating circuit in a household fire alarm is designed as a supervised loop that travels in series, with an End-of-Line (EOL) resistor at the far end. This arrangement lets the control panel monitor the integrity of the entire loop: the EOL creates a known resistance in normal conditions, so the panel can detect faults like opens or shorts anywhere along the run. If a device is triggered, the circuit behavior changes in a way the panel recognizes as an alarm; if there’s a wiring fault, the panel can distinguish it as trouble rather than an alarm. Wiring devices in parallel wouldn’t provide reliable supervision and could mask faults, while omitting the EOL resistor would leave faults undetected or misinterpreted. Hence, series wiring with EOL supervision is the correct configuration.

The initiating circuit in a household fire alarm is designed as a supervised loop that travels in series, with an End-of-Line (EOL) resistor at the far end. This arrangement lets the control panel monitor the integrity of the entire loop: the EOL creates a known resistance in normal conditions, so the panel can detect faults like opens or shorts anywhere along the run. If a device is triggered, the circuit behavior changes in a way the panel recognizes as an alarm; if there’s a wiring fault, the panel can distinguish it as trouble rather than an alarm. Wiring devices in parallel wouldn’t provide reliable supervision and could mask faults, while omitting the EOL resistor would leave faults undetected or misinterpreted. Hence, series wiring with EOL supervision is the correct configuration.