IN Brief:
- Scottish Woodlands has begun upgrading existing access tracks between High Constellation Wind Farm and Crossaig South substation.
- SSEN Transmission plans a 3.9km, single-circuit 132kV underground connection for the consented 50MW wind farm.
- United Infrastructure is expected to undertake ground investigations in late autumn, ahead of further access works planned for June 2027.
SSEN Transmission has started enabling works for the High Constellation Wind Farm Connection Project in Argyll, with Scottish Woodlands upgrading access tracks ahead of the proposed installation of a 3.9km, 132kV underground electricity cable. The connection will link BayWa r.e.’s consented 50MW wind farm south of Tarbert to the transmission network at Crossaig South substation.
Scottish Woodlands is improving sections of the existing tracks between the wind farm development and the substation, with the work expected to finish by the end of October 2026. The improvements will help provide access for subsequent ground investigations and construction activities along the proposed cable route. Installation of the underground electrical circuit has not yet begun.
United Infrastructure is expected to arrive in late autumn to undertake environmental and construction ground investigations, which SSEN Transmission anticipates will last approximately two months. A separate programme of temporary access-track construction associated with cable installation is currently expected to begin in June 2027, subject to the project’s progress through its remaining development requirements.
The connection scheme involves a single 132kV underground circuit extending from the wind farm’s proposed substation to Crossaig South. At the generating site, electricity collected from the turbines will pass through the wind farm’s electrical infrastructure before entering the high-voltage connection. The cable will then transfer that power to the existing network, within the limits established by its design and the connection agreement.
SSEN Transmission’s current plans specify approximately 3.9km of underground cable, with conductors rated to accommodate the wind farm’s 50MW installed capacity. Detailed electrical design will determine the final cable specification and installation arrangements. The published project information does not identify a cable manufacturer, conductor cross-section or confirmed date for energisation.
Although the route is comparatively short, installation requires coordination between electrical engineering and the civil works that determine how the cable is protected and cooled. Underground conductors produce heat as they carry current, with the surrounding ground influencing the rate at which that heat can be dissipated. Soil conditions, cable depth, spacing and backfill therefore form part of the design used to establish a suitable continuous operating rating.
The ground investigations are intended to provide information needed to plan these works, including the conditions likely to be encountered during excavation and the measures required to manage construction impacts. Where existing access tracks cannot accommodate the equipment needed for cable laying, temporary improvements or alternative arrangements may be necessary. SSEN Transmission intends to use access from the A83 and existing tracks where practicable.
At either end of the cable, the electrical design must provide suitable switching and protection arrangements. These allow faults affecting the circuit or connected equipment to be identified and isolated, while ensuring that the installation can operate within the requirements of the wider transmission system. The proposed connection runs from the wind farm substation’s 132kV busbar, through associated switchgear, to the existing Crossaig infrastructure.
The 50MW rating of High Constellation describes the maximum installed generating capacity rather than a continuous export level. Wind conditions and turbine availability will determine actual generation, while the cable and connection equipment must be capable of accommodating the electrical conditions for which they are designed.
SSEN Transmission notified Argyll and Bute Council in June of its intention to install the cable under the Town and Country Planning (General Permitted Development) (Scotland) Order 1992. The notification is recorded under reference 26/00939/PNELEC. The legislation provides certain development rights to statutory electricity undertakers, subject to the relevant conditions and other statutory requirements.
The network operator has also prepared a Voluntary Environmental Appraisal covering the proposed route. Construction arrangements will need to account for the commitments identified through that work, including soils, protected species and traffic management, alongside any outstanding wayleaves and approvals.
The project’s indicative programme has changed during development. Earlier information anticipated completion in 2027, whereas the June 2026 notification indicated that works could continue into early 2029. The October update establishes the immediate enabling-work sequence without confirming a new completion or energisation date.
United Infrastructure was awarded a contract for initial design, engineering and pre-construction activities associated with the underground connection in July 2026. The procurement includes an option for subsequent construction activities, distinguishing the awarded preparatory scope from the physical installation works that may follow.
Scottish Woodlands’ current track improvements mark the start of activity needed to make the route accessible for those later stages. Completion of the access upgrades, further ground investigations and the temporary construction access planned for 2027 will provide successive opportunities to confirm the remaining programme before the cable itself is installed and commissioned.
