NBN has purchased over 15,000km of copper cabling in an investment likened to buying steam trains.

The company in charge of rolling out the National Broadband Network revealed the purchase last week, which industry experts claim will be more expensive in the long run.

NBN Co revealed it had purchased 15,050km of copper cable from Australia, Brazil and Turkey, but says the National Broadband Network may still require even more of the outdated technology.

“The total purchase of copper will vary with final rollout technology mix, as each technology has unique characteristics that affect copper cable utilisation,” the company told the Senate.

Telecommunications consultant Paul Budde said the investment made Australia “one of the few western economies still buying copper in those quantities”.

“It’s like buying an investment in a steam train — it’s still running but it’s not the right infrastructure going forward,” he the Herald Sun.

“It’s investing in old technology.”

NBN chief executive Bill Morrow recently told the Senate that thousands of new homes would receive copper-based fibre-to-the-node connections “because it does not make economic sense to put fibre in just for a couple of homes on a block of land that has been remodelled”.

Mr Morrow admitted copper takes “more money to keep updated and to repair than fibre”, but would be about $2000 per home cheaper to install, so the company could “afford to pay more” for monthly repairs.

“All of that gets factored in for the economic decision of fibre-to-the-node being cheaper, even with those incremental costs,” he said.

The shifting costs of the compromised NBN model are explained in detail, here.