NFU Scotland members are understandably concerned about the impact of the proposed new 400KV power lines planned across Scotland on their businesses. To improve understanding of the processes, what is involved and why overhead lines are the preferred option NFUS met recently with SSEN.

This article lays out the key points SSEN suggest members need to be aware of and provides details about a NFUS/SSEN national webinar planned to answer more specific queries.

As we are all aware, there is a drive to achieve net zero by 2045. The governments of the UK have accordingly decided to invest heavily in renewable energy and the infrastructure that comes with it. As with all new developments it doesn’t affect everyone, and some are left with significant impacts to their businesses and local living space.

SSEN are clear they want to work with landowners, occupiers and tenants to achieve the best possible outcome with the minimum of impact.

In order to support this strategy, the projects have been developed around 'design and build' contracts where the same contractor is responsible for much of the design and the delivery of the works in conjunction with SSEN and those whose businesses are impacted.

Consultations – next round

Last year SSEN held public consultation events in relation to proposed 400kV substation sites and overhead line routes. SSEN are now preparing further consultation events scheduled for the end of May 2024 which will run for a month. These will set out the options for final substation site planning boundaries and overhead line alignments. Their 'preferred' options will also be displayed.

Ahead of the events, the consultation material will be made available for the general public. Property owners/occupiers will already have sight of the draft site/alignment options in order to encourage meaningful engagement in the form of site-specific feedback.

During the consultation period, all comments from landowners, occupiers, communities and statutory bodies will be assessed, considered and used to influence the design put forward for planning applications and formal land rights.

SSEN Transmission have stakeholder engagement at the forefront of their approach to these developments and aim to build trusting and long-term relations with landowners, occupiers and tenants. SSEN wants to achieve as many land agreements on a voluntary basis as possible. To provide voluntary consents, many parties will want to understand the overall impact of the development on their holding including the location of infrastructure as well as other elements of design such as access routes.

Action required

This consultation is your opportunity to discuss with the designers where specific pylons and other infrastructure should go to minimise the impact on your farming business. SSEN are open to discussion and negotiation. Sites for pylons like the intersection of field boundaries, corners of fields, even amending the layout of fields should be considered. At this stage there is still flexibility in the design to accommodate your business operational needs.

SSEN said: “It is essential that those affected take advantage of this opportunity to comment on the overhead line alignment options so their comments can be fully considered before the design is finalised for planning. In order to make this engagement as productive as possible, we are urging landowners/occupiers to provide comments not just in relation to their opinion of the proposed infrastructure project, but rather specific to the proposed position of the infrastructure on their holding as well as other practical considerations such as access into the proposed sites.”

Following the consultation events, reports on the consultation will be published setting out the chosen 'proposed' options to be taken forward for planning submission and formal land rights documents.

Underground cabling option

NFUS discussed the options for underground cabling with SSEN. For the following outline reasons SSEN opted for an overhead system of cabling.

Underground transmission circuits at 400kV require up to five cables per phase. In order to deliver the necessary capacity, which requires a three phase 400kV double circuit, up to 30 parallel cables will be required. For electrical reasons, these cables need to be suitably spaced out. To achieve the required spacing, a trench of over 40m wide would need to be excavated, typically between 1m and 7m deep. During the construction period, a working corridor of more than 70m wide is required for cable installation.

These cable trenches can also leave a residual visual impact on the landscape with a potential to result in significant environmental impacts and future land constraints such as planning and drainage.

The ongoing maintenance and inspection of underground cabling is significantly more challenging than that of overhead transmission infrastructure. The route must be surveyed periodically to ensure that the cable system is protected from external factors such as infrastructure development, ground movement and the risk of vandalism.

Whilst minor faults on cables are less common than on overhead lines, when cable faults do happen, they result in major disruption. Restoring power in the event of a cable fault can take significantly longer than for an overhead line. Faults on overhead electricity lines typically take anything from a few hours to a few days to repair and are generally easy to locate. Underground cable faults often require extensive works, specialist resource, tools and equipment to locate the fault, followed by significant civils works to expose the damage, replace the damaged section and then up to an additional month to carry out necessary cable jointing and testing of new sections.

An underground cable would be expected to have an operational life of around 40 years, similar to an overhead transmission line conductor. However, steel lattice towers would typically be expected to have a lifetime of around 50-70 years and when an overhead line conductor reaches the end of its design life, it can simply be replaced with limited impact to landowners. The replacement of an underground cable would be significantly more intrusive, impactful and disruptive.

Contractor protocols

Contractors are also being held to strict protocols in relation to accessing and working on private land. This is tied in with their contracts and SSEN Transmission are committed to close site construction management. These protocols are currently being developed and agreed with most of the utility providers by the NFUS chaired Road, Rail Utility Group which includes a range of organisations involved in statutory access to land.

NFUS/SSEN webinar

NFUS members will benefit from a national webinar being held in conjunction with SSEN on May 14 to explore the issues and actions members need to take if they are affected by one of the routes planned. Details on becoming a member of NFU Scotland are available on the NFUS website https://joinnfus.org.uk/