There has been widespread alarm and outrage since NBN Co announced it would wind back fibre-optic installations at some sites where the copper network seems fine.

The National Broadband Network will run on existing copper infrastructure in large areas where the previous contracts did not specifically state that fibre-optics would be used, NBN boss Ziggy Switkowski says.

The revelation that nothing will change for portions of the project means many contractors have been caught short, and now risk losing millions of dollars spent on new equipment.

Hobart civil works contractor, Andrew Bullock, told ABC reporters that he and many colleagues will be heavily affected by the new plan.

“This type of machinery that we've purchased, it's only any good for this type of project,” he said.

“You can't put it out in the field anywhere else to do anything else with it. It was basically bought for NBN installation works.

“[So] we'd like to talk to Malcolm Turnbull, we'd like to show him the investment we've made in the project financially and how we're all suffering because we've got no work, basically,” Mr Bullock said.

The Communications, Electrical and Plumbing Union said the assessment of Tasmania’s copper network was too optimistic.

“You can pop a pit lid in nearly any part of Tasmania and you'll find bits of the network that have just been hobbled together, shopping bags, Gladwrap used as a rush,” said union state secretary, Trevor Gauld.

“It is literally a situation where the equipment and the resources haven't been put in place,” he said.

On the federal level, the shadow communications minister Jason Clare says he will form an alliance with the Greens to blockade any Federal Government attempts to reduce the scale of the nation-wide network.

“I’m not going to support any legislation that is just going to entrench a second-class, second-rate broadband network based on old technology,” Mr Clare said.

“History will prove us right because we’ll look back in 20 years and everyone will agree that fibre to the premises is the right decision,” the shadow communications minister told a finance media outlet.

Communications Minister Malcolm Turnbull has not yet made comment on the situation.