Patent ID: 8446285

Claim:
An extension loop alarm notification output arrangement for use in a safety notification system, comprising: a) a notification extension loop connected to the safety notification system that generates an alarm notification output signal, configurable into a first and second wiring configurations of a notification appliance circuit; b) a negative voltage source configured to generate a negative voltage for testing the continuity of the first and second wiring configurations of the notification appliance circuit; c) a first resistor arrangement coupled between the negative voltage source and a signal output of the notification extension loop, the signal output configured to be electrically coupled to a feed conductor of the first or second wiring configuration of the notification appliance circuit; d) a processing circuit operably coupled to a circuit arrangement configured to detect a first voltage at the signal output of the notification extension loop, the processing circuit configured to generate a trouble signal output if the first voltage at the signal output is above a first threshold or below a second threshold; e) a positive voltage source configured to generate a positive voltage responsive to said alarm notification output signal to actuate said notification appliance circuit; and f) a semiconductor switch arrangement coupled to the signal output that is switchable between a first state in which the positive voltage is applied to the signal output and a second state in which the negative voltage is applied to the signal output; wherein the circuit arrangement includes a test voltage measurement circuit for said testing and configured to generate a measurement signal output based on the first voltage, and the processing circuit configured to obtain the measurement signal output and to generate a comparison value representative of a difference between a reference voltage and the first voltage for generating indication of circuit faults; and wherein the reference voltage is equal to the negative voltage divided over the first resistor arrangement and an end of line resistor arrangement of the notification appliance circuit.