To upgrade the national grid Transpower will put up its charges from April.
The company has warned customers to brace themselves for increases until 2015, when most projects will be completed.
Lines charges account for around 40 per cent of customer bills.
Mr Seed said while price increases in 10 regions exactly matched increased network charges, rises in Auckland and other 11 other regions contained a slight margin.
Earlier this month Mercury Energy announced a 5.8 per cent increase in power prices for households from April 1, pointing to lines charges as the reason for the increase.
Consumer NZ chief executive Sue Chetwin said some power firms would absorb the increases - and people should shop around to find the best deal for them.
SWITCH TO SAVE
* A government campaign is urging Kiwis to make use of Consumer NZ's Powerswitch website.
* By entering details into the online calculator at powerswitch.org.nz customers can see how much money they could save if they changed power companies.
* 12 per cent more households switched power companies from 2010, with a 74 per cent rise since records began eight years ago.