National grid operator Transpower has advised the northern West Coast to brace for the possibility of hour-long power cuts during winter.

International Panel and Lumber manager Rob Lawrence said: "It will affect production and we'll cope but the worst thing about this is there will be very short warning times."

The Gladstone sawmill, near Greymouth, needed plenty of warning to be able to shut down equipment safely, but the West Coast lines operator Westpower advised customers on Tuesday night that they might get as little as five minutes prior warning, he said.

"That is of major concern to us. We don't know when it's going to happen so we can't plan or put any contingencies in place," Lawrence said.

Westpower chief executive Rob Caldwell said the lines company was doing all it could to avoid the possibility of blackouts on the Coast.

"Water heating load is being shed between 5pm and 7pm. We are working with our retailers to look at the timing of major loads and monitoring load on the network to ensure we do our bit to assist when constraints are looming," Caldwell said.

The West Coast District Health Board was in talks with its energy retailer, Meridian Energy, yesterday to minimise the effect at Grey Base Hospital.

"We've been informed by Meridian that there is a 2 per cent chance of possible blackouts, and in the event of that we would get around one hour's notice to be able to get our emergency generators on line," a spokesman said.

Grey District Mayor Kevin Brown said his council had tried two years ago to alert the Government to the looming crisis.

"The repeated assurances by Government ministers that the matter was under control prevented a more concerted appeal for the industry to address the issue."

Brown said that without more electricity the momentum that was beginning to show with the growth of electricity-intensive industries would be compromised if not totally stopped. "For us it is not only a lines issue but also a generation issue. This situation brings generation schemes like Dobson hydro and a coal- fired power station on the West Coast to the fore."

Grey District Councillor Tony Kokshoorn said the possibility again of power cuts was an indictment of the inaction since Transpower conceded in its system security forecasts several years ago that security of supply to the West Coast and top of the island was "nothing short of abysmal".

"What have they done since then? Nothing. There's been a lot of talking but no action," Kokshoorn said.

Shortcomings with the transmission lines only compounded the lack of hydro electricity generation to cope with the explosion of industry in the top of the island.

"This is exactly what we were trying to get through to them in 2001.

"Now we've got the Pike River coalmine and Macraes (Reefton) goldmine confirmed -- and they'll be big users of electricity -- but another power crisis," he said.