A notification appliance and an alarm system are provided. The notification appliance comprises an alarm indicator and a control module, which is configured to perform notification applications by turning on/off the alarm indicator. The control module receives at least one of command instructions and notification signals, and directs the operation of the alarm indicator based on the command instructions and notification signals. The power condition of the notification appliance within the alarm system may be determined by comparing the notification signal and a predefined operating range for the notification signal. A fault indicator indicates a relationship between the notification signal and the predefined operating range.