Danger of Trees Near Power Lines

Why are trees a threat to my power supply?

Approximately 20% of the unplanned power outages you experience are caused by trees and other vegetation growing too close to power lines.

In high winds, trees and their debris can be blown onto power lines, causing the lines to short-circuit, and can also cause significant damage to our electrical equipment, resulting in power cuts.

What are the safety risks of trees growing too close to power lines?

Trees growing through, or close to, power lines are dangerous because they create a potential path for electricity to travel to the ground.

People that come into contact with this path (by touching, climbing, trimming or cutting down the trees) put themselves at serious risk of being electrocuted or receiving significant electrical burns.

Trees near power lines are also a serious fire risk in dry weather conditions; leaves or branches touching lines can catch fire!

The Electricity (Hazards from Trees) Regulations 2003

In order to manage the risk of trees causing safety or power supply issues on our network, we comply with the Electricity (Hazards from Trees) Regulations 2003.

The purpose of these regulations is to protect the security of supply of electricity and the safety of the public. 

The regulations give us the ability to issue a range of notices to tree owners, and ensure both safety and reliability of power supply are maintained by:

  • prescribing distances from electrical conductors within which trees must not encroach (growth zones); and
  • setting rules about who has responsibility for cutting or trimming trees that encroach on electrical conductors; and
  • assigning liability if those rules are breached; and
  • providing an arbitration system to resolve disputes between works owners and tree owners about the operation of these regulations.
How we help

Our Vegetation team carries out regular surveys of trees and vegetation throughout the areas we operate in.  We work closely with our customers to manage any trees identified as posing a risk to the reliability of our network or the safety of our community.

In the Rotorua and Taupo areas, our network passes through some of the country’s most densely forested areas, so we continually work with forestry owners to minimise the risk of trees causing power cuts for our customers.

Regardless of whether the powerlines are owned by Unison or are privately owned, the legislation states that it is the responsibility of the tree owner to ensure trees are maintained in accordance with the regulations.

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Service Lines

Private Service Lines are not covered by the Electricity (Hazards from Trees) Regulations 2003. Property owners are responsible for ensuring that trees do not encroach on their private service lines. Unison will not issue any notices for trees encroaching on private service lines. If you wish to trim trees on your property near a service line, you can request a safety disconnection so you can do so safely (some conditions may apply).

We also have a list of contractors approved to work near power lines.  Why not play it safe and use them for triming your private service line too?

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Unison Network Electricity Lines

Trees encroaching on Unison Network Electricity Lines are covered by the Electricity (Hazards from Trees) Regulations 2003. Tree owners are responsible for keeping their trees away from network electricity lines.

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Shelter Belts

If you have a shelter belt on your property, continue to trim as you have in the past. Make arrangements with Unison or other approved contractors to cut or trim the shelterbelt to ensure that the trees do not encroach on the Notice Zone. Note: First Cut and Trim notices do not apply, due to past agreements under the Shelterbelt Code of Practice.