Growth limit zones

The Electricity (Hazards from Trees) Regulations 2003 specify ‘zones’ which define the area around a power line which vegetation such as trees, vines or plants may not grow into.

In October 2024, the Regulations were updated to increase the minimum safe distances between vegetation 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.

Overhead Line Growth Limit Zones

Growth Limit Zone

The minimum distance that vegetation must be kept clear of power lines, even in windy or stormy conditions.

Cut-back Zone

Vegetation must be cut back so that they are outside of this zone.

Notice Zone

Gives owners more notice to address the risk earlier.

*Clear to the sky requirement

Underground Cable Growth Limit and Notice Zone

Controlled Access Zone

The Controlled Access Zone is four metres from any power line, and designates the area which must only be entered by a Unison-approved person.

If any part of a tree is within the Controlled Access Zone (four metres from any power line), an approved contractor must be used to cut or trim that tree.

The tree in this illustration will need to be cut or trimmed as it is inside the Growth Limit Zone. It is also within the Controlled Access Zone, so a Unison-approved person must be used to safely trim the tree. Contact your local arborist.