Transpower is taking the electricity line between the North and South Island out of service on Saturday for repairs, but says consumers will not be affected.
The grid operator is shutting the High Voltage Direct Current Link (HVDC) between 6.30am and 6pm, weather permitting, for planned maintenance on the overhead line.
Workers will replace several joints on the line as a preventative measure ahead of heavy winter demand, a Transpower spokeswoman said.
Transpower had co-ordinated with electricity generators about the work, which does not affect the undersea Cook Strait cables or the converter stations.
The line had experienced high load in recent weeks as the South Island hydro lakes reached high levels.
The HVDC is considered crucial to New Zealand's infrastructure as it allows power to be transmitted between the islands.
Transpower has increased its checks on the Pole 2 lines, which failed for three days in April, ahead of winter.
Pole 2, and the older Pole 1, convert power from AC to DC at Benmore in the South Island and back to AC at Haywards in the North Island, or the reverse if power needs to be sent south.
