A method and network device increases the power of the signal transmitted by the device on a wired communications network, such as a powerline communications (PLC) network, without exceeding the maximum allowable common-mode (CM) current specified by regulatory bodies. The device is first tested for regulatory body compliance on a standard network. The output voltage of the device is adjusted until the maximum allowable CM current is detected, and this voltage level and CM current are recorded and stored in non-volatile memory of the device. The device is then connected to the actual network and the output voltage set to the previously recorded value. At this voltage level, the CM current in the actual network is measured and recorded. The difference between the CM current measured with the device on the actual network and the maximum allowable CM current is calculated and used to calculate the amount the output power of the signal from the device can be increased without exceeding the maximum allowable CM current.