Several manufacturers, especially in forestry, may have to stay shut down for the next few days while the power link between the North and South Island is out of action.
High winds of up to 160km/h blew down three transmission towers in the Hanmer area of the South Island early onFriday.
With North Island generators turning to thermal generation to compensate for the absence of the southern link, the electricity spot price soared from $60 to $900 dollars per megawatt hour.
As a result some industries without price hedging have shut or drastically cut production.
Major Electricity Users Group chairman Terrence Currie says all industrial users will have to look closely at their manufacturing pattern tomorrow and see what is happening to spot prices.
He hopes generating companies aren't profiteering from the freak accident.
Temporary replacements for the towers are being built, but Transpower says the North-South link will be out of action for at least five days.
It is making assurances that the North Island isn't about to run short of electricity.
Spokesman Chris Roberts says while it will be next week before the Cook Strait link is back in use, the North Island won't suffer.
A 30-strong workforce is in Hanmer.
Chris Roberts says contractors have struggled to reach the site and are bringing in excavators, bulldozers, cranes and replacement equipment.
He says they will remove the damaged towers and wires, and prepare for the erection of temporary towers being brought in from Christchurch.
