Trees and power lines

Trees too close to power lines are a hazard and a major cause of power failures during bad weather. They can break power lines and network equipment, resulting in risk of serious injury or death as well as causing widespread power outages.

Tree owners’ responsibilities

Tree owners are responsible for their trees; the results of tree damage to power lines can be a significant cost to a tree owner. Please check your trees, hedges or shelter belts regularly. If you are not sure what to look for, please call us so we can help. Remember, trees need to be kept a safe distance away from power lines and other electricity network equipment because:

Trees and vegetation coming into contact with power lines can cause power outages, not just for the tree owners, but the wider community.
Children that climb trees close to power lines are at risk of serious injury or death.
In severe weather conditions, vegetation can become electrically ‘live’ and may electrocute anyone coming into contact with it.
In bad weather, trees can topple or branches break away causing damage to power lines resulting in a power outage. In snow or icy conditions, the additional weight on the tree can cause a similar scenario.
Trees close to lines may cause electrical sparking resulting in fire.
Tree roots can grow around underground electricity cables, rupturing the insulation and causing power outages.

What do the Electricity (Hazards from Trees) Regulations mean to you?

These regulations are to provide a safe electricity supply to you and to protect the security of electricity supply to everyone in the community.

The regulations place responsibilities on tree owners (you) and the electricity network operator (MainPower).

Following the regulations will help ensure security of supply to you and the wider community.

The Zones

The regulations specify different zones for trees growing close to power lines and other electricity network equipment: the Notice Zone and the Growth Limit Zone.

Please don’t wait to be reminded that your trees need to be cut. Be proactive, regularly inspect your trees and if they are in either the Notice Zone or the Growth Limit Zone they must be trimmed safely. Call us on 0800 30 90 80 for a free inspection and a quote from our utility arborists.

Be aware that if your trees cause any problems on our network, you can be charged for all costs of repair.

Cut / Trim Notice

If your tree is growing within the Notice Zone (Tree A) you will receive a legal notice from us saying that it must be trimmed soon because it is growing too close to power lines and equipment. If your tree continues to grow into the Growth Limit Zone (Tree B) you will receive a legal notice from us requiring the tree to be trimmed (by a qualified contractor) within a specified time frame.

This is because the tree is now too close to power lines and equipment, and could cause a power outage and / or harm the public. The notice zones vary depending on the voltage of the power lines.

Overhead line	Notice Zone	Growth Limit Zone
66,000V (high voltage)	5.0 metres	4.0 metres
33,000V (high voltage)	3.5 metres	2.5 metres
11,000V (high voltage)	2.6 metres	1.6 metres
400V / 230V (low voltage)	1.5 metres	0.5 metres
Notes: These distances are from the power line, not the power pole. These distances are a minimum and apply in all conditions, including high wind or snow. In most instances, the power lines that go to a house or building are low voltage power lines. Power lines that go down a street may be low or high voltage.

Offences committed by tree owners

There are penalties for tree owners who do not comply with a written request to cut their trees, or do not advise MainPower of the time and location of the cutting work.

On summary conviction, tree owners may be liable for a fine not exceeding $10,000 and a further fine of $500 for every day on which the offence continues.

If your trees are considered an immediate danger to our network, MainPower has an obligation to remove any hazard. If you have failed to keep your trees clear of power lines, or have not responded to our requests, then as the tree owner you are responsible for all costs incurred by us to remove any hazard and to repair any network assets that have been damaged.

Cutting trees near live lines

Due to the risk of danger, cutting trees near live power lines is a very specialised job. MainPower has its own team of experienced and qualified utility arborists (arborists trained to work near live lines).

Fall Hazard Zone

Tree owners should be aware that trees present a hazard if they fall and damage power lines. The closest a tree can be located is calculated on the basis of the height of tree plus 4 metres. Check that your trees are outside the fall hazard zone and consider trimming or removal to avoid causing damage and incurring future costs.