Mascot to Green Square cable project

Ausgrid is planning to reduce the electricity load connected to its Mascot Substation to maintain a safe and reliable power supply to customers in the local area. The project would involve installing new underground 11,000 Volt cables to connect to our Green Square substation in Alexandria.

Project need

Part of the existing electricity load at our Mascot substation needs to be transferred to a new substation in Alexandria to help improve service reliability in the area and reduce the risk of power disruptions and outages. The transfer would be achieved by installing new underground cables in streets between the two substations.

Planning cable projects

There are a number of considerations to factor in while planning cable routes. These include:

  • community impacts
  • availability of space around existing utility services
  • environmental and heritage impacts
  • cost (minimising the impact on electricity bills)
  • technical feasibility
  • traffic impacts
  • coordinating works with other infrastructure projects.

Ausgrid has investigated and decided on a proposed cable route for this project, taking into consideration the above factors - please see the proposed route map.

Project dates

The project is currently in the planning stage, with detailed design work and an environmental assessment underway. Ausgrid is working with local residents, businesses, the Council of the City of Sydney and Bayside Council to plan the work to ensure community impacts are minimised.

Pending internal approval, construction would start in late January 2018 and take about twelve months to finish. Work to install the new cables in streets would be completed in mid-2018, but work to transfer the electricity load from the Mascot substation to the Green Square substation would extend into late 2018.

Ausgrid will keep residents, businesses and other stakeholders updated on what to expect during the project stages.

Project approval process

Ausgrid is the approving authority for these works under the NSW Environmental Planning & Assessment Act. As part of the approval process, Ausgrid is doing an environmental assessment for this project and liaising with the surrounding community, councils and other relevant authorities.

Community engagement

Ausgrid started engaging with Bayside Council and the Council of the City of Sydney about the project in October 2017 and has also been coordinating with other authorities about their work in the area.

Engagement with residents and businesses located along and around the proposed cable route started in mid-November 2017 with door knocks and face to face meetings. The first project newsletter was distributed in mid-November 2017.

We will continue to engage with the community and stakeholders during each stage of the project. Ausgrid welcomes questions or comments about the project at any time (see project contacts top right). Community feedback assists us to identify all potential issues and address them in our construction plans to minimise impacts.


This project would involve installing the new cables through streets in Mascot and Alexandria via trenching in roads and horizontal drilling (boring) under two existing stormwater culverts, one in Ralph Street in Alexandria and the other in Hughes Avenue in Mascot.

In some locations, the cables would be installed into existing conduits. As with any construction work, there would be some noise and dust, and temporary traffic, access and parking disruptions, but we would make every effort to keep these to a minimum.

Construction would involve.

  • digging trenches, approximately 1 metre wide, to lay conduits (plastic pipes) to hold the new cables
  • filling trenches and resurfacing the area temporarily
  • excavating underground joint pits and communication pits at various locations along the route to feed in and join sections of cables together
  • boring under the stormwater pipes in Ralph Street and Hughes Avenue, using Horizontal Directional Drilling (HDD)
  • Permanent restoration of all impacted areas.

The trenching and resurfacing work typically takes about three days outside each property depending on ground and weather conditions. Feeding in and joining the cables can take several weeks to complete.

Generally, restoration work is done in two stages; excavated sections of road are refilled immediately and temporarily resurfaced to allow normal use by traffic. Final restoration would be completed in consultation with the Council of the City of Sydney and Bayside Council and relevant authorities either as sections of work are completed or once the overall project is finished.

Any potential impacts associated with this work are assessed as part of the project's environmental assessment. Measures would be put in place to minimise impacts on the community and local environment.

Ausgrid's work hours are 7am to 6pm Monday to Friday, and 8am to 1pm on Saturdays. Some night work would be required on O’Riordan Street and Botany Road to minimise the impact on traffic, businesses and the general community during the day. We would contact affected community members in advance of this work with more information.