A Tararua wind farm near Palmerston North vandalised earlier this week has been partially fixed.
Intruders broke into the switchyard early on Monday morning, drained cooling oil from the transformers and made an apparent attempt to steal underground copper cables.
A spokesperson for Trustpower, Graeme Purches, says one of its two transformers has been fixed and the windfarm can start putting electricity back into the grid as soon as the wind starts blowing.
The company is repairing the second transformer.
Mr Purches says there is still a huge amount of disbelief in the industry at the break-in as what the vandals did was very dangerous.
The cost of the outage and repairs has been estimated at $250,000.