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Working around trees and vegetation

How to safely keep trees clear from power lines

Trees and vegetation growing in and near our power lines is a major cause of power outages, especially during storms.

It’s the responsibility of the landowner the tree is on to keep it pruned and away from our lines. We undertake regular tree surveys to ensure that areas close to our lines are clear but we also ask the public and people working on-site, to help us keep an eye on things.

If you’re trimming trees and vegetation either on your own land or as a contractor for a client, it’s very important that you do not attempt to trim any trees within four metres of power lines yourself – only our trained arborists or an approved contractor can do it because of the danger of electrocution.

Northpower approved contractors to trim your trees

These contractors are approved by us to work close to power lines, please contact them directly to arrange your tree trimming:

Think Trees Arborist Services Northland
Phone: 021 0238 6231

What happens if trees are left untrimmed?

Because of the danger that trees in power lines cause, there are penalties for non-compliance with the government legislation Electricity (Hazards from Trees) Regulations 2003.

Tree owners who receive a Cut or Trim notification from us must ensure the tree is trimmed to outside the Notice Zone (NOTZ) within the timeframe in the notification outlined below.

Not doing this can result in fines up to $10,000 plus up to $500 per day for continuing offences and the tree owner could also be liable for costs if our lines or equipment are damaged by the tree.

The Growth Limit Zone (GLZ)

The Growth Limit Zone (GLZ) is the legal minimum space surrounding any power lines that must be kept clear of trees. It can vary depending on the voltage of the power lines, however no person or piece of equipment is permitted within four metres of our lines.

For safety reasons, trees and vegetation in the GLZ can only be trimmed by us or an approved contractor.

The first tree trimming is provided free of charge but any ongoing trimming will incur a charge.

It’s important you don’t trim the trees in the GLZ yourself due to risk of electrocution.

The Notice Zone (NOTZ)

You can trim any trees in the NOTZ provided we’ve given written authorisation. Please contact us and let us know the tree location and when the work will be done – at least three working days before you want to carry out the work.

If your tree is growing in the NOTZ, we may send you a Hazard Warning Notice advising that the tree needs trimming.

Growth Limit and Notice Zones vary according to the line voltages.





50 to 66kV

66kV or greater

Growth Limit Zone






Notice Zone






No longer want to maintain a tree?

It’s the land and tree owners decision whether they want to continue to maintain a tree or have it removed. If they don’t want to organise and pay for regular maintenance, they can declare ‘No Interest’ in the tree if:

  • the tree was naturally sown or
  • the tree was planted and at the time of planting the tree owner believed the tree, when fully grown, wouldn’t interfere with power lines

They need to read, understand and fill out the No Interest Tree Form and we’ll advise whether we will remove the tree or what trimming we can do.

Please note that if this option is chosen, the trees may be trimmed to a level deemed suitable by us or removed.

No Interest Tree Declaration Form

Doing some planting? We can help

Please don’t plant trees that will grow large close to power lines – low shrubs and small trees are best. You can view a list of our recommended trees here.

When planting trees, please always check for power lines and underground cables before you dig.

When purchasing a property, you may also like to check if mature trees are growing near power lines, as there can be large maintenance costs in keeping them trimmed.

Trees and vegetation growing near service lines

It’s the home or business owners responsibility to keep trees and vegetation clear of their service lines – the line that brings power from our network at the property boundary to the home or business.

Trees and vegetation that grows in or near service lines can cause flickering power supply or a total outage.

When maintaining and pruning near service lines, it’s best to be safe and organise a temporary power disconnection.