Understanding Electricity and Trees

Guides Health & Safety

24th January 2020 | Info

Electricity is a power source that you can’t see and will kill. It must be considered as being very dangerous and never taken lightly when working near or next to. While it is true that wood is not conductive for electricity, water is, and when there is a high enough voltage, it will travel through any moisture within the wood. So, with a living tree being full of water within its sap, they can become live in certain situations which could result in electrocution.  

It is a regular occurrence that trees come in to contact with electrical supplies from either overhead lines or other electrical sites such as substations. When working on trees in these situations, it is important to know what is safe to undertake and what the limitations are before carrying out any works. 

The variables of a job can be quite extreme, and any rules and regulations will and do vary depending on the DNO (Distribution Network Operator) for that area depending on their policy. You can find your DNO for your area at the Energy Networks Association: 


The main rule to follow is that if you are not qualified or don’t hold the right level of competency then under no circumstances should you go near overhead lines, electrical equipment or enter a substation without the correct competency or appropriate supervision from the DNO. 

The Health & Safety Executive have helpful advice on the matter which can be found here: 


Other useful information on the subject can be found in the Health & Safety Executive Guidance Note GS6 – Avoiding danger from overhead power lines: https://www.hse.gov.uk/pubns/gs6.pdf 

Within these guidance notes, it states that establishing exclusion zones from powerlines or electrical equipment is imperative and notes the following safe working distances for the exclusion zones, which are as follows: 

 Low Voltage lines – 1m 

11kV and 33kV – 3m  

132kV – 6m 

275 and 400kV – 7m 

Here, the kV reference refers to the number of thousands of volts that the line carries. For example, 11kV is 11,000 volts – which is a serious amount of electricity.  

It is also important to be able to recognise the different types of powerlines or electrical equipment that is found on the network to be able to establish what is what when assessing the scope of works for tree work operations in these circumstances. There is a range of training and certification from NPTC in Arboriculture for Utility works and UA1 covers Basic Electrical Knowledge. The link below shows all the qualifications achievable in this specialised area of Arboriculture; 


Further reading can be found on the Forestry Industry Safety Accord – FISA guidance notes 804 Electricity at work: Forestry, that has further information and guidance:  


Please note – Guidelines can vary depending on the DNO regulations, this article is just a guide – Always seek the DNO’s advice before carrying out any work, around electricity. 

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