A power supply extracts electrical power from the electro-magnetic field surrounding a high voltage power conductor and conditions the derived input power to provide a stable power source for instrumentation and communications equipment. The communications controller is a local network router that routes serial data traffic to selected communication devices such as an instrumentation processor, a power supply processor, or a maintenance port controller. The router forwards the data to other communications equipment and forwards data from the communicating equipment to an external network providing substantially simultaneous communications between the external network and the instrumentation processor, power supply processor and maintenance port controller.