Overhead Power Lines and Trees
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.
About the Electricity Industry
The Electricity Industry in the UK has three key stakeholders.
- Generators are responsible for generating the electricity we use in our homes and businesses. Generated electricity flows into the National Transmission Network and through to the regional Distributors or District Network Operators.
- Distributors or District Network Operators (DNOs) are the owners and operators of the network of towers and cables that bring electricity from the National Transmission Network to our homes and businesses.
- Suppliers are the companies who supply and sell electricity to us the consumer.
What the Law Requires
District Network Operators (DNOs) e.g. EDF Energy, CE Electric, Central Networks, Northern Ireland Electricity, Scottish Power, Scottish and Southern Energy, Electricity North West and Western Power Distribution, are currently required by law (Electricity Act 1989) to keep trees clear of OHPLs for reasons of public safety. To find your DNO, please follow the link www.nationalgrid.com/uk/Electricity/AboutElectricity/DistributionCompanies/
Since 2009 the District Network Operators are required maintain a sufficient clearance between trees and overhead power lines in order to avoid them interfering with the supply and so improve reliability.
These requirements will probably mean that more extensive tree cutting will be carried out than in the past, 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 works 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.
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.
The Regulations that currently apply to the Electricity Industry are the Electricity Safety, Quality and Continuity Regulations 2002.
The statutory powers available to electricity companies in respect of tree works are available under Schedule 4, paragraph 9 of the Electricity Act 1989 (as amended).