What is a powertap? Estimated Reading Time: < 1 Minute 462 Mike Coleman July 25, 2016 NMEA 2000 Cables and Connectors 0 7064 Every NMEA 2000 network requires a power source, which is usually supplied by a powertap. The powertap is used to energize the 12 volt power and ground wires found within the NMEA 2000 cable.