TasNetworks (TN) – which supplies power to more than 295 000 residential, commercial and industrial customers – owns, operates and maintains the electricity transmission and distribution network in Tasmania. This includes 22 400 km of distribution overhead lines and underground cables, 227 000 power poles, 18 large distribution substations and 33 000 small distribution substations.
The island state has already seen the impact of global warming, with the average annual temperature increasing by 1.1°C since 1910. Over the same period the annual average rainfall has decreased. The result is that the number of days with dangerous weather conditions and the risk of bushfires has increased across the region.
The growing risk is illustrated by a severe incident that occurred in February 2025, when dry lightning ignited more than a dozen fires in the west of the island. This caused more than 94 000 hectares of Tasmanian wilderness and World Heritage Areas to be burned.
To mitigate the impact of storms on network resilience, the risk of fire in highly vegetated areas and to preserve wildlife, TN has embarked on a proactive programme to investigate alternatives to bare wires for our 11 and 22 kV overhead distribution networks. The reason is that while bare wire has served us well for many decades, it produces sparks when it contacts dry foliage or other objects.
Wildlife is an added challenge for TasNetworks, coming in the form of the Tasmanian wedge-tailed eagle, an endemic endangered species. This magnificent bird tends to inadvertently fly into powerlines, causing them to clash. Sometimes the bird is electrocuted. Not only is the loss of one of these birds a tragedy, but it can also bring a fine of around AUD $100k. Another issue is with possums climbing power poles. While vegetation is top of the list for fire starts, wildlife interacting with the network is number 2.
Why not go underground?
Burying cables underground significantly reduces bushfire risk as there is little interface with dry vegetation and wildlife. The challenge is that undergrounding, at over $800 000 AUD per km, is capital intensive and generally not financially viable, unless the terrain is very favorable or the undergrounding is aligned with civil works being carried out by other organisations.
Another option is to use covered conductor for overhead lines in place of conventional bare wire. The insulated jacket acts as a protective barrier that encapsulates the conductor. This prevents the release of sparks, reducing fire risk. It enhances reliability as it prevents faults arising in the first place. Furthermore, it dramatically reduces the risk of members of the public or wildlife coming into contact with the conductors.
Covered conductor is well established as a possible solution in Tasmania. TasNetworks has used HVABC (high voltage aerial bundled conductor) in its distribution network since 1995. However, it was used sparingly. This is because HVABC was very heavy and tough to work with. This created challenges for installers when handling and stringing lines in the field.
A new generation of three-layered covered conductor
Considering the issues with the established alternatives to bare wires, we are trialing our first full-scale installation of New Generation Covered Conductor (NGCC) from Amokabel, the Swedish cable manufacturer. This covered conductor has three layers of covering. A semi-conductive inner layer provides flexibility, a high-grade electrical insulator in the middle gives electrical performance and a tough polymer jacket provides protection. The outer layer needs to be particularly tough to withstand mechanical abrasion, as well as intense UV light.
This fully sealed cable system prevents water ingress and meets the EN 50397-1-2006 international standard for covered conductors. An important feature is that the design life of NGCC is more than 40 years, which is comparable to bare wire.
The use of advanced lightweight insulation materials means that NGCC can be restrung on existing poles. This could help save TasNetworks, and ultimately our customers, the cost of replacing or adding infrastructure.
We estimate that using NGCC is around 10% of the cost of undergrounding.
A study by CSIRO (Commonwealth Scientific and Industrial Research Organisation) found that this type of covered conductor reduces bushfire risk by 98%.
First field installation, at Neika
The first full scale installation of NGCC was carried out at Neika, a rural locality about 10 km southwest of the city of Hobart. This rugged and heavily treed area is on the side of a mountain. It was selected for its significant vegetation, which has given it a reputation for outages and reliability issues.
The installation by our TasNetworks crew went very smoothly. Initially, the team was concerned about the NGCC being fragile, but they came to appreciate that it is quite robust. They found it easy to work with, appreciating that it was clean to handle and used the same tools as bare wire. The job took about the same time to install as bare wire, with no changes to equipment such as recovery trailers.
Since the installation was carried out in February 2024, we have had five instances of trees falling on the overhead line. One of these trees weighed 700 kg – according to the loadcell on the crane we used to lift it off – and it still didn’t result in an outage.
Only one of these treefalls resulted in a fault that caused an extended{?} outage, and that was because the insulation was damaged on a steel crossarm. In the other cases, we only had to switch the power off for as long as it took to cut the trees away. That means the impact on customer supply was reduced significantly as the outage was for only around one hour, rather than the four to six hours that is normally needed to repair an overhead line. Most importantly, none of these incidents resulted in a fire start.
Performance and cost
Following on from the Neika project, we’ve started replacing HVABC with covered conductor. The first HVABC replacement was carried out at Ansons Bay, in the northeast of Tasmania. The feedback from the crew was so positive that they asked to set up additional NGCC lines in the area using the materials remaining from the original project.
It is too early to report in detail on performance. However, the initial feedback is that outages have been reduced.
The trial projects have used 62 mm NGCC. Overall, the cost increase was estimated at around 20% compared with bare wires. This provides an excellent return on investment (ROI) in terms of improved network resilience and security of customer supply and reduction in risk to wildlife and fire start incidents.
At Neika, TasNetworks is well on the way to recovering the additional cost of NGCC over bare wire.
Next steps
TN is currently planning NGCC installation at two more sites: Sisters Beach in northwest Tasmania to replace HVABC; and Launceston, a city in north Tasmania, to protect heritage trees. Overall, TN will replace 18 km of HVABC and 10 km of bare conductor to evaluate NGCC.
Then, providing there is positive feedback from the trial sites and distribution system designers{?} become comfortable with using NGCC, TN will focus on additional areas where wildlife is at particular risk or where salt pollution is a challenge.
TN is interested at looking at NGCC for recloser leads and droppers, where it should be easier to work with.
A viable alternative
The experience from TN’s full-scale trials shows that the Amokabel covered conductor is easy to install and work with. It will allow TasNetworks to mitigate many of the potential risks that traditional open wire networks pose, at a reasonable cost, making it a viable standard replacement alternative. Reasons to install Amokabel covered conductor include reducing customer outages and their duration (reliability) and the incidence of fire starts.
