Reconductoring for added Capacity in the Scottish Highlands

SSEN increased the capacity in challenging terrain quickly and cost-effectively by using the existing Right of Way (ROW) and structures with ACCC® Conductor. This approach helped in saving both costs and time, while also mitigating any potential environmental impacts in an ESA and globally renowned area of outstanding beauty.


Capacity increase


Towers Retained


Upfront cost Savings


Load Requirement: Increase capacity from 89MVA to 198MVA due to increased regional demand and Lochaber Smelter.

Line Importance: Critical backbone connecting Scotland’s west coast with the network. Grid access for aluminum smelter with own hydro plant. Connects the town of Fort William and Major Customer (Smelter.)

Condition: Towers and foundations to be retained.

Clearances: Meet 6.7m clearances in all areas during maximum operation.

Outages: Single circuit only with 10-hour ERTS.

Safety: Maintain SSEN Safety Culture “If it’s not safe we don’t do it.


Retained 97% of the Towers: Only 5 of the 156 towers needed to be replaced. Three of the five were required to increase clearance over a major trunk road due to new clearance regulations.

Type Tested: ACCC® Monte Carlo has been type tested by SSEN according to BS standards and UK conditions, including heat-cycle testing.

Improved Grid Reliability: PL16 is a legacy tower used throughout the UK, Monte Carlo ACCC® Conductor increased capacity and reduced sag.

Increased Efficiency: Re-using the existing asset and extending the life while doubling MVA ratings with minimum disruption.

Future-Proofing the Grid in Steep Terrain

Scottish and Southern Electricity Networks (SSEN) Transmission’s operating region covers a quarter of the UK landmass. SSEN Transmission is responsible for the planning, design, construction, and maintenance of a network which currently comprises 146 Grid Substations, 5165 km of circuits and 14,994 towers and structures. Many of the 132 kV Network towers in the UK were constructed in the 1950’s & 60’s. These towers came with both historical ground clearance and under capacity issues. Replacement (or “rebuilding”) would likely be expensive, contentious and time consuming.

The background to this project was reconductoring for capacity increase with minimal tower reinforcement, in addition to reduced sag in some heavily wooded areas.This 132kV line connects Fort William on the Scottish Highlands west coast to the Supergrid sub-station in Fort Augustus via Loch Lochy. It passes through Invergarry, north and south Laggan, along Loch Lochy, to the west of Spean Bridge then in parallel with the highway connecting Torlundy and Scotland’s strikingly beautiful west coast at Fort William. This line forms the main network tie-in between the backbone 400kV network near Inverness and much of the west coast of Scotland, taking in wind farms and the hydro generation plant mentioned above.

The end customer for this project is SHET (Scottish Hydro Electric Transmission plc) (the Transmission business of SSEN), who are taking full advantage of the capacity increase benefits of CTC Global’s ACCC® Conductor on a number of current and planned projects.

“Reconductoring vs rebuilding saved years of time in permitting and construction, significant environmental advantages, and tens of millions of pounds in project costs.”


44 km

circuit miles

132 kV

Single circuits



Conductor Size: ACCC® ULS Monte Carlo

Project Highlights
  • Extended the asset life of its existing tower fleet and future proof the network using the existing towers and modern conductors.
  • Power increased from 89 MVA to 198 MVA.
  • Offered many second tier benefits such as resistance to cyclic load fatigue and corrosion.
  • The success of the project which was independently recognized with the Utility Week award of “Capital Project of the Year.”

This installation builds on an excellent relationship with SSE, thanks largely to the quick reaction and teamwork within CTC Global. The success of this project, together with the cooperative approach CTC Global staff showed whilst working through a major potential problem, has led directly to a further 120km project in the Inverness area (Tomatim – Boat of Garten).

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