Mechanised vegetation management near live power linesCopy Link

Scottish and Southern Electricity Networks (SSEN) Distribution is responsible for ensuring a safe and reliable supply of electricity to 3.8 million customers in communities across its network in central southern England and the north of Scotland. SSEN Distribution employs more than 3,500 people, including skilled engineers, customer service teams and future energy experts many of whom live as well as work in the communities they serve.

By enabling a smarter, more resilient electricity network, SSEN Distribution ensure that local communities from the Shetland Islands to the Isle of Wight, and Portsmouth to Aberdeen continue to receive the power they need, both now and in the future. With a commitment to ensuring customers have more involvement in vital infrastructure investment decisions, network reliability is a key priority for SSEN-D and the customers it serves.

As part of this commitment to resilience and increasing network reliability, SSEN have to undertake extensive vegetation management activities, including tree felling and pruning, to maintain safety clearances and avoid unplanned outages due to damage caused by falling trees or branches.

Typically, much of this work is done manually by specialist contractors or appropriately trained in-house staff. Tree cutting activities can vary depending upon the species being cut, availability of suitable access, landowner’s preferences, and the voltage level of the associated overhead line.

Currently a variety of cutting techniques are used:

• From ground level using insulated rods  
• From appropriate access platforms – mobile elevating work platforms (MEWPS) etc  
• Where necessary, trees are climbed by specially trained staff to allow access to use chainsaws etc.

These manual approaches present health and safety challenges, especially when working on diseased or dead trees, such as ash trees affected by Ash Dieback. In this specific case, the trees become very unstable, leading to significant risk when employing conventional manual felling techniques. Ash Dieback is of primary concern at present; however, other diseases are starting to affect UK trees due to global warming and globalisation of trade and movements.

Vegetation management activities cover all voltage levels within SSEN-D from low voltage (415V) up to 132kV, across the entire license area. Where safe and practical, the works are performed with live power lines to prevent interruption to power supplies, but where necessary planned outages are organized to ensure that works can be carried out safely.