Masterton business owners say they've been left in the dark over the reason for major powercuts during busy shopping times.
They say Powerco hasn't given any explanation for an outage last month, and another in the Christmas shopping season last year. Another cut could be devastating for businesses.
Russell Carthew, owner of Paper Plus, Queen St, said the last power cut on November 20 had cost him thousands of dollars at a vital time of the year.
The lack of communication from Powerco was "unacceptable," he said.
"There's nobody who can tell us why it happened, how it happened or if it's likely to occur again over the coming weeks," he said.
"We're terrified that it is going to happen again before Christmas."
Lynn Simpson, owner of Black Sheep Jewellery, Queen St, also said the power blackouts were a mounting source of anxiety during a "difficult time" for retailers.
About 400 customers were left without power for several hours on November 20 due to an electricity network fault, the cause of which was still to be determined, Powerco said.
Retailers were hit by a similar cut on December 13 last year, and Mrs Simpson said business owners were still waiting for answers from Powerco as to what happened on that occasion.
"It only affected one side of the commercial area and three or four blocks and it's a regular occurrence," she said. "Trading is difficult and you can't recoup those sales, that's a hell of a lot of revenue for the day gone."
Mrs Simpson said she was frustrated with the response from Powerco.
"It would be nice to have some reassurance as to why this is happening on a regular basis because we can't afford to have this affecting our Christmas takings."
Powerco Network operations manager Phil Marsh said the company worked to operate a safe and reliable network which met or exceeded industry standards. He said there would be "unplanned power cuts from time to time" for a range of reasons, and no electricity network company could guarantee an uninterrupted supply of electricity.