Almost 30 per cent of Ausgrid’s electricity network is underground, connecting substations and customers via a web of cables that run under footpaths, roads and even waterways.
It means that poles and wires do not have to get in the way of traffic, pedestrians or buildings, particularly in built up city areas or where easements for overhead networks are too narrow, unsafe or heavily vegetated.
When our crews replace or install underground cables they first have to dig new trenches, often over long distances and install PVC conduits that will safely house the new cables.
The trenches are dug in small sections and when the conduits are laid they are buried with excavated material before the trench is covered with a temporary fill. This means motorists and pedestrians can use the area immediately after work is completed on each small section.
Once the entire cable conduit is installed, the new cables are pulled through. The cables are then connected to the electricity network or customers’ premises. Unfortunately, in some cases this work can take several months or longer.
The material used to cover the trenches is known as temporary reinstatement. It consists of a hot mix of soft black tar that sets hard enough for cars and pedestrians to safely use.
By using temporary reinstatement, our crews do not have to leave long open trenches in local neighbourhoods for considerable periods of time. It means that local streets and footpaths are returned to motorists and pedestrians straight after we complete a small section of work.
Ausgrid works with local councils and the Roads and Maritime Services to plan this underground cable work and in most cases they complete the permanent reinstatement work.
Each year Ausgrid pays local councils and the RMS to repave or resurface about 50 kilometres of footpaths and roads.
We inform a council when our cable work is complete and they schedule the permanent reinstatement with their local contractor as soon as possible.