Telstra's copper network is being considered as part of the NBN.
The union representing Telstra field staff says a decade-old gel-like casing used to repair part of the copper network is rapidly decaying it, casting new doubts over the value of a mixed-technology national broadband network (NBN).
The yellow encapsulate, which was used from the year 2000, was designed to protect the copper from water damage.
But at a recent Senate select committee hearing on the NBN in Perth, Communications, Electrical and Plumbing Union (CEPU) WA branch president John O’Donnell said the casing had the adverse effect: trapping the water and accelerating corrosion.
The repair practice was discontinued in 2006 but Mr O’Donnell estimates the casings are still in place across more than 40 per cent of the network nationally.
He told Fairfax Media the gel didn't stop water from flowing into the joints, the most environmentally vulnerable part of the network. It allowed it to penetrate up to 1.5 metres of cabling and accelerated the corrosion process.
He had seen the damage first hand as one of thousands of workers contracted by Telstra to eradicate the gel from joints in Darwin, north Western Australia and Queensland, he said. Those regions we more susceptible to the effects of decay because of the warmer and more humid climate.
"The majority of the places where it was installed were closest to the customer," Mr O’Donnell said. "This is important in the concept of fibre to the node. The highest activity levels for a communication technician when they are doing installation and fault rectification work are generally in that last mile."
Telstra spokesman Scott Whiffin declined to comment on the extent of the problem or whether the gel was accelerating copper's decay, but he said Telstra invested hundreds of millions of dollars a year to improve and expand its coverage.
"We haven’t released that information but we are constantly installing, replacing, repairing and upgrading copper lines throughout the network. And in the main, and for the vast majority of our customers, our copper network provides a high quality fault-free service," Mr Whiffin said.
“The gel is a superseded repair method that had not been used for some years. We in fact have a replacement program that’s been under way for quite a few years now, so many of these joints have been upgraded. Any that cause problems get replaced, as do any found by our techs as they undertake their day-to-day work."
The union also claimed the exact value of the damage caused by the bungled gel fix could be deduced using Telstra’s Customer Network Improvement (CNI) database, which logs information about faults on the network. Mr O'Donnell said it was imperative that the extent and cost of the damage be revealed as it affected the government's plans to modify the design of the NBN to use existing copper to connect 71 per cent of customers' premises to fibre nodes, or street cabinets.
Changes to the NBN rollout require Telstra to renegotiate the $11.2 billion agreement it had with NBN Co for the decommissioning of its copper.
"The Australian taxpayers have a right to know how bad or how good that copper network is, and that CNI database is the biggest clue that we can get to find out," Mr O'Donnell said.
Mr Whiffin said the CNI recorded minor maintenance work, not service faults or network quality, and did not indicate maintenance or remediation costs.
In November the NSW branch of the CEPU claimed copper's network was "nearly beyond repair". It said recycled plastic bottles and bags had been used to insulate wires in several Telstra pits in the Illawarra region. Photos it supplied at the time showed tangled wires, wires submerged in water and wet wires even when inside the plastic shields.
At the time Telstra said such temporary fixes were common until a permanent repair was carried out.