A Central Otago community was left scrambling when their power was cut for six hours yesterday without notice.

Lines company Aurora Energy, which is upgrading its network, started replacing a pole after unexpectedly deferring work the week before.

But a glitch in their notification system left about 51 people around Cromwell and Bannockburn completely in the dark.

It was just another day for Mt Difficulty Winery's chief winemaker's Matt Dicey, until the power went off just after 9am.

"There was no notification at all. We were actually sitting in our office doing a tasting. The team at the cellar door were busy doing stocktakes and getting ready for the day's trading," Dicey said.

"We had 36 or 40 customers already booked for lunch, which was pretty much a full sitting and the power went off."

He called his generation company to find out what had happened.

"We discovered this from Pioneer (Energy) that actually they'd had no notification from Aurora that the power outage was happening... but that the planned outage from last week had been moved to this week, but they hadn't bothered telling anyone that that was actually happening."

With roughly two weeks notice for last week's planned outage, Dicey said they had paid about $600 to hire and install a generator to cover them last Thursday.

He'd been running it for a few hours to ensure consistent power when he called his generation company and they told him the outage wasn't going ahead.

The company hasn't been told until hours after the outage was meant to start and it wasn't rescheduled, Dicey said.

They were lucky to get a generator at short notice yesterday and that it wasn't the middle of peak vintage season, he said.

"We'd have wines potentially spiralling out of control. We wouldn't be able to control because we didn't have access to refrigeration to be able to maintain temperatures and all sorts of things so it just so happens we're at a reasonably quiet time of the year and we could actually live with an outage and it's not super bad. But if this occurred to us in the middle of our vintage, it would be potentially catastrophic," Dicey said.

The outage comes as Aurora Energy is proposing to hike power prices to address historic underspending with Central Otago expected to face the highest increases.

Just down the road at Felton Road Winery, winemaker and general manager Blair Walter said his staff had a little more notice after seeing a contractor drive into the vineyard towards one of their transformer.

"She went and approached him and asked him what they were doing there with not having come in to sign in. And they said that they were just checking the powerbox and the direction of power leaves our transformer, and they said that we'd be experiencing a power cut and this was at 8:45am and the power went off at 9.10am."

If the outage occurred during harvest, they'd likely have to send home 50 grape pickers home, he said.

"It could have consequences on wine quality with fruit in the press that would be sitting in there, having excessive skin contact. It would be really damaging to the wines so a real concern.

"Similarly if we were bottling, we usually have you know up to 10 people working on the bottling line and, you know, it would be really interrupting to have to shut that down."

A partially-emptied tank of wine could oxidise from one day to the next, ruining the wine without power to regulate the temperature, Walter said.

The lack of notice was shocking and it had been getting more common over recent years, he said.

"It's to do with the ageing network here that hasn't properly maintained and now they're scrambling and with all the controversy over the extra charges that they're going to lay upon all of us, you know, I would have thought that they would be behaving a lot better in terms of notifications and compensation for business where businesses are going to suffering for not having electricity," Walter said.

In a statement, Aurora Energy customer and engagement general manager Sian Sutton apologised for the lack of warning, saying ordinarily customers could expect notifications.

"Unfortunately due to a recent IT upgrade there was a glitch in our retailer notification on this outage, which has now been rectified. Retailers and customers were unfortunately not made aware through direct notification," Sutton said.

"We intend to contact each customer affected by this planned work and in particular wish to apologise for the inconvenience this has caused to local business and residents."

Pioneer Energy was contacted, but was unable to comment by deadline.