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Why aren't my power lines underground?


The Auckland region has a mix of both overhead and underground power lines. 55% of customers have power lines underground in front of their properties. All new developments in the region have power lines underground as the site works for construction and road building typically provide easy and cost-efficient access to install the lines.

However, some areas have overhead power lines because:

  • Undergrounding costs up to 10 times more per kilometre than overhead power lines

  • Costs are especially high in areas of Auckland built on hard volcanic rock which is common in central Auckland.

  • In rural areas, undergrounding power lines is prohibitively expensive given the lower population numbers per kilometre.
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The cost of undergrounding ultimately ends up with consumers, which is why we still use overhead power lines in some cases. They’re affordable and easy to repair when something goes wrong. We use the technology that’s best for each area so we keep the costs down for our customers.

Wouldn't undergrounding all power lines prevent outages?

Unfortunately, faults still occur on underground electricity cables that result in outages. These can happen when:

  • Contractors or DIYers hit underground electricity or gas cables

  • Underground cables are more resilient to tree damage but can still be damaged by storms if trees are uprooted.


Underground faults may also take longer to find. A field crew may spend hours digging up sections of a road before identifying where the issue lies.
 
 

 





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