Mulgrave's Waverley Park, a former AFL ground that closed in 1999, is a 1250-home housing estate to be completed by late 2013.

Homes range from $480,000 to $810,000, and more than half have been built and sold. Prices for exclusive oval-front homes start at $810,000.

As part of a deal for the land between developer Mirvac and the State Government, high-voltage transmission lines had to be put underground.

However, Mirvac recently applied to the Department of Planning and Community Development to leave the power lines above ground, claiming it would cost about $30million to move them.

More than 200 residents have written to the department to object.

Home owner Bruce Nicol said potential buyers were given copies of planning documents for the estate that stated power lines would go underground.

He said residents had not been offered compensation for breach of contract or an expected decrease in house values and they were concerned about chronic long-term exposure to electromagnetic fields from living within 20 metres of the lines, which carry 220,000 volts.

Mirvac told residents the cost of putting the power lines underground had increased from nearly $12million in 2002 to about $30million.

It claimed putting the lines below ground would be less attractive and the terminal stations could pose health and safety risks.

"We as residents are very suspicious about how they have arrived at that [$30 million] number," Mr Nicol said. "Some have taken a view they have inflated that number.

"But we've analysed Mirvac's balance sheet at the end of June which stated they had $5billion in net equity, $7billion in assets, $1.1billion cash in the bank and the chief executive earned $2.8million — they can afford it."

A Mirvac spokeswoman said that after more than five years of negotiations with powerline owner and operator SP AusNet and reviews about engineering design and costing, Mirvac now believed leaving the lines above ground was the best solution.

She said investigations concluded the underground solution was "not commercially viable" and safety issues could not be managed to the satisfaction of Mirvac or SP AusNet.

Mirvac would comply with the relevant published guidelines in relation to electric and magnetic field exposure, she said.

A State Government spokeswoman said the plans and issues were under consideration.

She could not say when a decision would be made.