PROBLEM TO BE SOLVED: To provide a fire alarm system that can give an alarm output as an intrinsic function while dispensing with a circuit in each fire alarm for generating self-driving power from commercial power supply and simplifying wiring for connecting each fire alarm.;SOLUTION: The fire alarms are at least one master alarm with a line power supply circuit and slave alarms without a line power supply circuit, and are interconnected parallel by a two-wire signal line. The slave alarms are each configured to operate on driving power from the line power supply circuit supplied from the master alarm to the two-wire signal line. The master and slave alarms each comprise a voltage level fluctuation control circuit for dropping the voltage level of the two-wire signal line to a predetermined report level when a fire detection part detects a fire factor such as smoke or heat, and a fire alarm control part for outputting an alarm when determining that the voltage level of the two-wire signal line has been dropped to the predetermined report level.;COPYRIGHT: (C)2006,JPO&NCIPI
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