A device monitors an appliance that receives power from a source. The device includes a first coupler that couples the device to the power source. A second coupler couples the device to the appliance. A monitoring circuit is connected to the first coupler and the second coupler to monitor power supplied by the source to the appliance. A communications circuit also is provided. The monitoring circuit provides data based on the monitored power to the communications circuit for output to the first coupler. The communications circuit may include a receiver that receives a signal from the first coupler to control the monitoring circuit. The communications circuit also may include a transceiver that receives a signal from the first coupler to control the monitoring circuit and to transmit monitored power data.