Stringing optical ground wire over live 500-kilovolt lines had never been done in Australia.
Australia’s transmission sector hit a new milestone recently, with the Lines team at Consolidated Power Projects Australia Pty Ltd (CPP) completing a first-of-its-kind operation: the stringing of optical ground wire (OPGW) over live 500kV (kilovolt) circuits.
Replacing shield wire while keeping the system energised is difficult under any conditions, but doing so across live transmission lines, freeways and rail corridors ratchets the challenge to a national first.
“This wasn’t just a technical step forward. It’s a fundamental shift in how we think about executing major works on critical infrastructure,” says Sean Dunn, General Manager of Transmission Lines at CPP.
The operation significantly reduced the outage time for client AusNet, reflecting not only the team’s precision but the growing need for flexible, low-disruption methodologies in Australia’s tightly balanced grid.
An ambitious step
While CPP had previously completed live OPGW works on a double circuit 220kV line, the 500kV project marked a significant leap in complexity.
“The electrical induction is so much higher at 500kV,” explains CPP’s Wade Pihama-Bishop, the construction supervisor for CPP’s first non-outage OPGW replacement on the live 220kV double circuit line.
“Working on or close to live circuits induces an electrical current in OPGW and non-energised conductors. Even if you’re not touching the live 500kV conductor, you can still get zapped – or worse – just by getting too close.”
“Induction is invisible, unpredictable and deadly,” Dunn said.
“It’s absolutely a critical risk that needs to be mitigated. Induction, working over live conductors, and complicated crossings all required specific work methods and controls to keep workers safe. It’s complicated. That’s why no one had strung OPGW over live 500kV before.”
To mitigate the danger, CPP deployed a comprehensive control framework, underpinned by Safe Approach Distances (SADs) and what Dunn calls “the capacity to fail safely”, based on CPP’s safety program ‘The Capacity Model’.
“We don’t just plan controls for hazards. We plan for what happens if the control fails. Will someone get hurt? If yes, then it’s not safe. It’s about engineering that margin for error, even if no one ever intends to make one,” he says.
Engineering the impossible
At the heart of the method is a concept called cradle blocking: a length of dielectric rope threaded across spans with cradle blocks at 7–10 metre intervals that acts as a safety net beneath the OPGW as it’s pulled.
“We attach the new wire to the old one and pull it through using the existing shield wire,” Pihama-Bishop explains.
“But if something breaks or slips, that wire can’t fall. The cradle blocks catch it before it can touch anything live or fall to ground.”
To further manage induction, the team used stringing rollers with grounding arms installed, along with other proprietary gear. Drones were also used to run ropes between towers, avoiding the need to place a robot on lines where the weight would have increased risk. Another important element was the use of the latest technology in stringing gear that allowed the tension in the OPGW to be finely controlled throughout the pull.
The work required navigating high-traffic corridors, including the Western Freeway and Melbourne to Ballarat railway – both of which remained operational during works.
CPP site manager Kurtis Allum says the pre-approvals alone took months.
“Just getting the traffic management plan over the line took two to three months,” he says.
“You’re proving every methodology to stakeholders, from road authorities to rail operators. You can’t afford to leave any doubt in their mind.”
Training, trust and terrain
Beyond technology, it was the crew’s readiness that made the job viable.
“We can’t do jobs like this without the field crews and crew leaders. They’re up there with the induction, the wind, the height… and still need to be precise,” says Allum.
Pihama-Bishop says that many of the team had to upskill for live-line work.
“We brought in barehanders – guys used to working live – but for others, it was their first exposure to this level of complexity. It’s a big deal. These projects are going on their résumés for good reason,” he says.
Dunn agrees.
“At times, you’ve got team members five kilometres apart coordinating movements. One misstep and you can snap a line or worse. So communication and crew culture is everything. We had full-team stand-downs to review safety whenever needed. The operators have the authority to stop work if they’re not comfortable. And they do,” he says.
That culture, Allum says, extends beyond the site.
“We live the ‘I am my brother’s keeper’ motto. Barbecues, debriefs and group dinners –they’re not perks. They’re part of building trust,” he says.
Three years, four firsts
CPP’s lines division is just three years old, but it’s already notched up several national firsts.
After being restructured under new ownership, the team quickly grew from a two-state operation into a 50-strong national outfit.
In that time, it completed the first dual-circuit 500kV cut-in, followed by the 220kV live OPGW project, then the 500kV version, and more recently, a world-first 500kV conductor transfer – executed live.
This sequence of high-voltage milestones showcased not only technical proficiency, but a growing capability to execute under increasingly complex, live conditions.
“Many of the team brought significant industry experience to CPP, including our Construction Manager, Walter Fiedler, with over 45 years in the trade,” says Dunn.
“In the first year, we had maybe a dozen guys. Now we’re at 50. It’s not just about size, but capability,” says Pihama-Bishop.
“You cross paths with these blokes in 20 years and say, ‘Remember when we did that first 500kV job?’ That’s legacy stuff.”
Every time work can be undertaken without a scheduled outage, it carries significant value for the asset owner.
However, the real value goes beyond time.
“Avoiding outages reduces strain on the rest of the network,” says Dunn.
“It prevents customer disruption and gives the asset owner more flexibility across their maintenance calendar.”
Setting the standard
With CPP’s work drawing attention across the sector, Dunn notes a cautious optimism.
“Our clients have seen what’s possible, and that’s great. But there’s a risk if others try to replicate it without the same competency, planning or safety culture,” he says.
“You can’t just reverse-engineer this. It takes years of experience to know what the real risks are – and how to fail safely if something goes wrong.”
Looking ahead, the team is already planning another first-of-its-kind job. While details are still under wraps, it involves replacing entire towers without de-energising the conductors on a voltage and tower type never done before.
The pride and the payoff
Despite the scale and stress of the job, morale remains high. According to Allum, it comes down to shared pride and purpose.
“There’s real satisfaction in knowing we’ve done something new, something that made a difference. And we did it together. That stays with you,” he says.
Dunn takes great pride in the work, even with the risks involved.
“I think we work in the best industry in the world,” he says.
“And to see this team – one we built from scratch – pull off something this complex, safely, and professionally… it’s one of the highlights of my career.”