Selling half of Ausgrid for $16 billion is an outstanding result, New South Wales Premier Mike Baird says, but the Opposition argues he could have made more money.

Australian companies IFM Investors and AustralianSuper are the new owners of 50 per cent of Ausgrid, which powers 1.7 million homes and businesses.

It is the second electricity network to be partially privatised, as part of Mr Baird's 2015 election promise to raise $20 billion for infrastructure by selling half of the state's poles and wires.

"On the back of today we are underwriting for the future generation rail, roads, schools and hospitals," Mr Baird said.

Mr Baird said after the Government pays $10 billion in debt, there will be $6 billion in net proceeds from the transaction.

In August, the Federal Government intervened to block the sale of Ausgrid to two Chinese bidders citing "national security concerns".

Premier insists he got the best possible deal

This time around, the Government did not put Ausgrid out to tender, but Mr Baird has insisted this is the best possible deal.

"We know the market better than anyone on the planet in terms of what these assets are worth," Mr Baird said.

"We've obviously relied on expert advice but importantly an independent transactions committee oversees this and determines 'is this market value?'

"The view is this is an outstanding bid for the people of this state."

But Opposition Leader Luke Foley said the Premier should have seen if there were higher offers.

"This is like selling your house to the first person who knocks on your door and makes a bid," he said.

"The Premier tells us this is what he's good at — selling things — yet the market's been gagged here."

Last year, NSW sold Transgrid for $10 billion to a consortium of Australian and foreign investors.

Only bid from Australian-only investors: Treasurer

NSW Treasurer Gladys Berejiklian said this was the only bid from Australian-only investors.

"This bid does not require FIRB (Foreign Investment Review Board) approval," she said.

"That is a plus for NSW."

The Premier said that does not mean the Government would not consider foreign bidders when it sells the third and final network to be privatised, Endeavour.

"The national security concerns that were identified were specific to this asset," Mr Baird said.

"Clearly we will engage with FIRB as Treasury launches the third process but our expectation is that of course, it will be open to foreign investment."