  We describe the power distribution systems and grounding schemes built for
the near and far detectors of the NOvA long-baseline neutrino experiment. They
are used to power the avalanche photodiodes and their thermoelectric coolers,
the front-end boards that read out, digitize and time stamp the signals from
the avalanche photodiodes, and the data concentrator modules used to receive
and format the data from the front-end boards before sending them to a farm of
computers used to build the events. The system powers 344,064 readout channels
in the far detector and 20,192 channels in the near detector.
