Brownhill-Pakuranga cable jointing project

Location: Auckland
Start date: June 2024
Completion date: Stage 1 completion June 2025, Stage 2 completion June 2026
Project client: Transpower
Project partners: CB Civil, Pipeline Civil

Northpower / Project case studies / Brownhill-Pakuranga cable jointing project

Collaborating to deliver great outcomes

Transpower identified a need to proactively replace 45 cable joints on the 220kV cable between the Brownhill and Pakūranga substations in Auckland. We were chosen as the primary contractor to deliver this project. This critical piece of infrastructure maintains the electricity supply into Auckland and Northland. This prudent approach in replacing these joints will ensure the cable operates effectively for the next 30-40 years.

Timelapse of joint bay cable repair

The 10.5 km cable traverses both rural and suburban areas of East Auckland, starting in farmland in Whitford, through Dannemora, East Tamaki Heights, Botany into Pakuranga.

Two experienced civil contractors, CB Civil and Pipeline Civil were engaged to deliver the project with Northpower. Transpower engaged an overseas specialist for the cable jointing work. Our responsibilities include coordinating the cable jointing and civil work, ensuring the health and safety of 60 onsite personnel, as well as the public in close proximity to the cable.

The project is being delivered in two phases: June 2024 to June 2025 and June 2025 to June 2026. Over 77,238 person-hours have been put towards the delivery of this project.

77238

person-hours invested

60

personnel onsite each day

45

cable joints along 10.5km of cable

Specialists in cable repair

Cable repair requires highly specialised technical skills. First, the site is cordoned off and excavated using a digger or jackhammer if under the roadway. The exposed work area – called a joint bay, is then secured with retaining walls, scaffolding, and waterproof wrap.

To expose the cable joint, rock-breakers remove Fluidised Thermal Backfill (FTB) concrete around the 220kV cables. Extreme care, appropriate work practices and tools are used to avoid damaging the cables.

After the cable joint repairs are complete, the area is restored: the wrap is removed, the joint bay filled with Thermal Resistive material, the earth backfilled, and any impacted roadways repaired.

Ensuring staff safety

To ensure a ensure a smooth project delivery for Transpower, Northpower’s project team has effectively addressed and resolved health and safety issues that have emerged during the course of works.
In collaboration with civil contractors and the international specialists, the team has developed several innovative solutions including:

- - Portable air-conditioning was brought into the plastic-wrapped work areas to reduce heat stress for workers.
  - Rock breaking crews were expanded from two to three members to minimise strain experienced from vibrations and given rotating rest periods.
  - A conveyor belt system was co-designed to remove broken concrete from joint bays, reducing heavy lifting for crews and lowering the risk of injury.
  - Using a special extension trailer with crane to transport lengths of cabling up to 24m long to site, instead of moving a 30T cable drum between the joint bays. This avoided expensive traffic management plans, and time-consuming site set up, while minimising the risk of injury.

Ensuring public safety

Northpower applies robust safety protocols to keep the public safe at our worksites. Each worksite is cordoned off with large barriers to prevent the public entering a hazardous environment. In cases where the barriers block visibility for motorists, convex safety mirrors and dedicated traffic management is installed to improve visibility.

Ensuring reliable supply

So far, the project has successfully delivered zero harm worksites, with works currently on track to meet Transpower’s deadlines.

The completion of this project will ensure a reliable supply of electricity to Auckland and Northland, powering economic growth in both regions for the next 30-40 years.