Line 86 is a 330 kV single-circuit transmission line, running between Tamworth and Armidale (111 km), and was constructed in 1982 using mostly composite wood pole (two piece wood pole) structures. Line 86 is the only 330 kV line in our network that was not constructed using steel towers. The unique construction of this transmission line means that wood rot beneath the composite pole joint sleeve is prevalent throughout the composite wood poles that are utilised along the line.
Transgrid is applying the Regulatory Investment Test for Transmission (RIT-T) to options for managing risk on Line 86 (Tamworth-Armidale). This would involve replacing existing transmission infrastructure to address condition issues with options which also have the potential to provide additional wider wholesale market benefits.