Originally Posted by
Marilyn Munroe
Benmore is connected to the South island grid by several AC transmission lines. These give the southern terminus of the HVDC link the ability to drag in power from other stations and send it north even if the Benmore Power Station is idle.
The line from Manapouri, which marches across the Christchurch Port Hills, stops off at the Twizel switchyard which itself has connections to Benmore. This is the most likely method of delivering electrons from Manapouri to the North Island via the HVDC link.