Additional inspections of all the power poles across the south west region have confirmed the electricity network is in safe working condition, with electricity distribution business Powercor today releasing results of recent testing.
Powercor chief executive officer Tim Rourke said the pole inspections in the network servicing a region from Warrnambool to Port Campbell and Hamilton in January and February revealed high standards of strength in the infrastructure.
Of the 19,663 power poles tested, only nine have been replaced as a priority (0.05 per cent of poles) after being rated as unserviceable. This compares with an annual average of 0.06 per cent of inspected poles rated as unserviceable and replaced across the entire Powercor network.
“During these inspections we found the number of poles needing to be replaced was lower than what is usually found during our normal inspection cycles. The condition of the poles in the south-west region came out better than average, compared to the Powercor network overall,” Mr Rourke said.
“Our Powercor teams based in Warrnambool and Colac do an outstanding job to continuously maintain the network and their extra effort in the past few months to accommodate the additional testing and inspections is much appreciated.”
Related article: Infrastructure Australia says EVs a high priority
Powercor undertook the additional pole inspections out of respect for the heightened sensitivity in the community regarding network safety following the St Patricks Day bushfires in 2018. Of the nine replaced, only one was due to levels of sound wood. Four had been struck by lightning during recent storms and four were due to visual appearance.
The additional inspections came after community members raised concerns about the appearance and age of poles and, as a result, 15 poles were removed from the Sparrow and Craven Spur lines near Terang over December 2018 and January 2019.
Two independent industry experts were engaged to assess the breaking strength of these poles at specialist pole supplier Kopper’s Grafton test facility, witnessed by representatives of Energy Safe Victoria. Of the 15 poles, 13 successfully passed the pullover test, and one was excluded as an invalid result. The remaining pole had been rated as unserviceable and failed at a level just above the region where it was inspected. Powercor has identified a procedural improvement to identify similar issues in the future.
Mr Rourke said that eight, including the worst looking poles, had an actual safety factor close to or better than the strength of a new pole.
“It just emphasises that it is the health of the pole which is important, not its age or what it looks like,” he said.
“These tests show our approach to inspecting, maintaining and replacing poles is reliable and safe.”
Related article: Bat out of hell: Flying foxes increase power outages
In addition to the recent inspections, Powercor’s inspection methodology has been updated with new measures for pole serviceability, increased inspection frequency and clarifications to the use of signage on poles.
“Our safety program is always evolving as technology and methods that network businesses like ours use to inspect infrastructure is improving. We continually review and investigate ways to deliver a safer network for the community and these latest changes are an example of this work,” Mr Rourke said.
Under the new measures:
- Powerlink has replaced the ‘Limited Life’ category to ‘Serviceable – Added Controls’ reflecting that the poles are still strong but will be inspected more frequently
- Those rated ‘Serviceable – Added Controls’ will be inspected annually in preparation for the summer season
- Poles will be classed as unserviceable when their safety factor has dropped to 1.40. Previously, they would be replaced if their safety factor reduced to 1.25. (The higher the safety factor, the stronger the pole.) This conservative approach will add an additional 5mm – or 15 per cent – of sound wood to poles.
- Powercor is undertaking another round of testing to evaluate new technology to improve pole inspection methods.
The inspections were in addition to the annual safety program, which in 2018, involved inspecting about one in three of the 571,800 wood, concrete and steel poles across the Powercor network, in line with Victoria’s regulatory standards.
Under the new methodology, the number of unserviceable poles expected to be replaced each year will increase from 1200 to approximately 2200. These changes will be incorporated into Powercor’s Draft 2021-2022 Regulatory Reset Proposal, with the business seeking $332 million for its overall pole and line replacement program.