Danger of trees near power lines

Why are trees a threat to my power supply?

Around 20% of our unplanned power outages are caused by trees and other vegetation growing too close to power lines.

High winds can blow trees or debris onto power lines, leading to short circuits and significant damage to electrical equipment, which can result in power outages.

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

Trees growing through or near power lines create a dangerous path for electricity to travel to the ground.

Anyone who touches, climbs, trims or cuts down these trees put themselves at risk of being electrocuted or receiving severe electrical burns.

Additionally, trees near power lines pose a fire risk during dry weather, as leaves or branches touching the 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 regulations set out your obligations as a tree owner and prescribe the minimum safe distances for trees growing near network power lines.

In October 2024, the regulations were updated to increase the minimum safe distances between trees and power lines, and a new ‘clear to the sky’ requirement for some trees.

The regulations include:

• Any tree or vegetation that is considered a risk to our power equipment
• Minimum safe distances between trees and power lines (Growth Limit Zones) 
• Responsibilities on tree owners and line owners for ensuring that clearances are maintained  
• Setting out the penalties that each party faces for failing to comply with the regulations
• Outlining the arbitration process for handling disputes between tree owner and line owner 

How you can help:

• Plant wisely: Avoid planting near power lines if possible. If planting is necessary, choose the right species. Unison provides guidance at www.unison.co.nz/planting-guide.
  
  
• Check your property: Regularly look for overgrown vegetation and ensure it is kept at least four metres clear of power lines.
  
  
• Call in the experts: If trimming or cutting is needed for your property, contact your local arborist. They’ll liaise with Unison before starting work to ensure it’s done safely.
  
  
• Report problem trees: Spot trees or vegetation touching power lines elsewhere? contact Unison at 0800 2 UNISON (0800 2 86476) or visit www.unison.co.nz/problem-tree to report the issue.
  
  
• Know your responsibilities: Property owners must keep trees clear of power lines and underground power cables. Failure to maintain them could result in damage costs or fines. Learn more at www.unison.co.nz/tree-notices.

How we help:

Our Vegetation team carries out regular surveys of trees and vegetation throughout the areas we operate in. We work closely with customers to manage trees that pose risks to the reliability of our network or the safety of our community.

In the Taupō and Rotorua areas, where our network passes through some of New Zealand's most densely forested areas, we collaborate with forestry owners to reduce the risk of trees causing power outages.

Whether the power lines are owned by Unison or privately owned, legislation requires tree owners to maintain their trees according to regulations.

Trees near our network lines

We monitor trees growing close to our network lines and will send you a First Cut or Trim Notice, or a Cut or Trim Notice, if your tree is too close.

Keeping trees clear of lines keeps everyone safe. That’s why it’s important trim or cut your trees when we ask you to. If you don’t act on a notice within the given timeframe, you could face a fine of up to $10,000, plus an additional $500 per day until the work is completed. You may also be liable for any costs associated with damage to power lines or equipment caused by your tree. Please work with us to keep our network safe.

Trees near your service line

Property owners are responsible for ensuring that trees do not encroach on private service lines, which are usually low voltage (230 V or 400 V). We will not issue notices for trees encroaching on these lines.

Working near power lines is dangerous and those cutting trees near live lines are at risk of electrocution or serious injury. If you need to trim trees near a service line, you can request a Safety Disconnection from Unison to make sure it's done safely (some conditions may apply). Your local arborist may also be approved to work near power lines, so consider using them for the job.