Abstract: A brush wear monitor system for dynamoelectric machines includes a sensor imbedded in a brush to provide a signal indicating a predetermined amount of brush wear. The brush wear signal is provided through an isolation network to an indicator circuit. The indicator circuit includes a first indicating lamp which is illuminated in the absence of a signal from the brush wear sensor to indicate normal operation and a second indicator lamp which is illuminated only in response to receipt of a brush wear signal from the sensor. Upon receipt of a signal the first indicator lamp is extinguished and the second indicator lamp is illuminated. A manually operated test switch is provided to check the operation of the indicator circuit.