Overhead Power Lines and Trees

Overhead Power Lines (OHPLs) and Trees

Introduction

Trees adjacent to overhead power lines can represent a public safety risk and interrupt the supply of electricity, especially in severe weather.

It is therefore necessary to manage them in order to minimise these potential problems.

Related Pages

BT Lines, Telegraph Poles and Trees

Natural Target Pruning - How and Where to Remove a Branch

Protected Trees- Tree Preservation Orders and Conservation Areas

Pruning Mature Trees

Responsibilities of a Tree Owner - A General Guide

Responsibilities of a Tree Owner - Works to Trees

What the law requires

District Network Operators (DNO's) e.g. such as Scottish Power, United Utilities, CE Electric UK, EDF Energy and Western Power Distribution etc. are currently required by law (Electricity Act 1989) to keep trees clear of OHPLs for ‘reasons of public safety’.

New laws which came into effect in 2009 mean that DNO's must also keep sufficient distance between trees and overhead lines to avoid them interfering with supply and so improve reliability.

The new requirements mean that more extensive tree cutting will be carried out, with trees that pose a high risk being removed.

Extent of the tree works

There are no statutory minimum clearances for trees adjacent to OHPLs, however the electricity industry work to national guidelines for safe distances. These vary according to the voltage level at which the power lines operate and whether or not the tree is climbable.

Guideline clearance distances for voltages less than 33kV:

• 3.0m - from a branch able to support a person's weight.

• 0.8m - from a branch unable to support a person's weight.

The national guidelines also specify that:

All tree works must be carried out in accordance with good arboricultural practice and
the relevant British Standard.

In the event the work undertaken achieves the national guidelines for safe distances but falls short of best practice the landowner should contact the responsible DNO.

An example of tree work that achieves the national guidelines but falls short of best practice

Who maintains the tree?

In theory, the owner of the land is responsible for managing the trees and can reclaim the costs incurred from the electricity companies.

However, cutting trees in close proximity to live overhead power lines is inherently dangerous and not recommended unless the operative is suitably experienced and qualified.

In practice, the work is normally undertaken by the DNOs at their own expense.

The DNOs should always seek the consent of the landowner prior to carrying out any tree works.

If agreement cannot be reached

All DNOs should try to proceed by agreement with landowners. If agreement cannot be reached the DNOs have statutory powers (under paragraph 9 of Schedule 4 to the Electricity Act 1989 as amended) to require work to be carried out to any tree that is so close to an overhead line that either:

• It obstructs or interferes with installation, maintenance or working of the line; or

• It poses an unacceptable level of danger.

Where the DNO has exercised these statutory powers, the DNO shall ensure that any works carried out are in accordance with good arboricultural practice.

In addition to this, as little damage as possible should be inflicted on other trees, nearby fences, hedges or growing crops. Any felled trees or parts of trees should be removed in accordance with the owner’s wishes. The DNO also has the obligation to make good any damage done to the land.

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