Aspects of the present disclosure are directed toward a system and apparatuses for calibrating metering circuitry. An example system includes a first adapter including a plurality of receptacles proximally arranged in a circular manner on a first surface of the first adapter, the plurality of receptacles configured and arranged to be connected to endpoint controlling circuitry configured and arranged to communicate over the power lines or by using a RF communication, characteristics related to power usage of an endpoint device in a PLC network. The system further includes a second adapter including a plurality of electrical contacts disposed on a first surface of the second adapter and a plurality of terminals disposed on a second surface of the second adapter opposite of the first surface. The plurality of terminals can be physically arranged so as to plug into corresponding inputs on meter calibration circuitry. Further, the system includes a housing fixedly securing the first adapter and the second adapter and enclosing circuitry configured, while in operation, to facilitate calibration of the endpoint controlling circuitry by the meter calibration circuitry.