Premier Mike Baird has responded to union claims household bills will increase if the state's electricity poles and wires are sold, by releasing a Treasury-commissioned analysis showing customers have paid lower charges in Victoria and South Australia after privatisation.

But the report by Ernst and Young notes one reason for the discrepancy is government-owned businesses in NSW and Queensland have recently spent billions upgrading their networks and Victoria and South Australia may soon follow suit.

The state-of-play in the power market.

As unions backed a call for a referendum on the issue and MPs prepared to debate it in party room meetings on Tuesday, Mr Baird said he was ''not in the business of implementing policies that increase electricity bills for NSW families''.

"The scare campaign being unleashed by Labor and the unions simply isn't backed up by facts - network prices have been more than 100 per cent higher for NSW's publicly owned system than in the privately owned Victorian or South Australian networks,'' he said.