Meridian has sent letters to its 2500 Marlborough customers informing them of the rise, which follows annual price rises by other electricity suppliers Trustpower (8.1 percent in June) and Contact Energy (nine percent in July last year).

Genesis Energy public affairs manager Richard Gordon said he could not recall any recent price rises and the company did not have any plans to do so for at least a year.

Meridian spokesman Alan Seay said electricity increases were never good news but that the price rise was necessary and reflected the overall cost of supplying electricity.

"We need to move our prices once a year on average and so it's happening with all our customers up and down the country."

However, Marlborough is leading the way in price rises for Meridian. The eight percent facing customers here is well ahead of the national average of 3.5 percent.

Customers in central Hawkes Bay get off lightly with a 1.4 percent increase, while a few others face rises comparable to Marlborough, such as Buller on 7.8 percent.

Mr Seay said the considerable price increase in Marlborough was attributable to increasing demand in the South Island, where dairying and viticulture were flourishing. As a result, Meridian was investing money into new hydro schemes and wind farms in Wellington and Central Otago.

"We have a very active and ambitious development portfolio and we are investing loads of money, hundreds of millions of dollars, in making sure this country has enough electricity so that the lights stay on in the future.

"The options we have for doing that are more expensive to bring on stream than they have been historically. It has to be paid for and it is the users that pay."

Marlburians also faced smaller rises in previous years, so were in line for a larger increase in this annual review, he said.

Graeme Purches, community relations manager for Trustpower, which introduced similarly large price increases in June, said electricity prices were also affected by the changes in transmission costs.

"Wholesale electricity costs have been increasing for the region. Fifty percent (of Marlborough's electricity) is imported and we're paying increasing transmission costs."

Although Meridian's new prices take effect at the beginning of September, Marlborough Family Budgeting Service vice president Joyce Somerville had advice for those hard hit by the sizable increase.

She suggested customers pre-pay some of their bills during low-use summer months so "they have got a wee bit extra to fall back on in winter".

She had not had many people asking for specific advice on how to pay their bill but felt some were struggling and spending money put aside for other purposes.

"They're using their food money to pay their power bills. I think that's probably what's happening," said Mrs Somerville, who delivered 17 food parcels from Marlborough's Food Bank last week. This was "slightly on the high side" for this time of year, she said.

"It's a cold winter and I have heard a lot of people complain that they have got to keep warm."

She was doing her own investigations to compare prices between Marlborough's four electricity suppliers.

For customers who also want to shop around, Marlborough Lines provides a service through its customer services group where people can discuss their power usage and get assistance to work out their best option.

Operations manager Brian Tapp said, "It's not our job to tell people what to do, more just clear the fudge. It is confusing when you look at a bunch of tariffs on a page and are saying which one is me.

'Different power companies package their prices differently and have a range of tariffs. I think it's best done on a one-on-one type basis."

Kerry Chapman, of the customer services group, said the website www.consumer.org.nz/powerswitch was also an excellent site to compare prices as there was no simple rule that applied to everyone.

"You need a copy of your power bill. You go through a process and series of questions then it tells you which option is the cheapest. It is a very good tool for those who have access to a computer.

"There are so many variables such as the different number of people in a household and the level of overall usage. You have to look at individual situations," he said.