The Denny to Wishaw Network Upgrade Project includes new infrastructure, and some changes and reinforcements to existing infrastructure, including:
- Construction of a new double circuit 275kV / 400kV overhead line, running north-south from Bonnybridge 275kV substation to a point near Glenmavis in North Lanarkshire, where it will connect to the existing 275kV overhead line (known as XX Route) that runs between the Easterhouse and Newarthill 275kV substations;
- Uprating one side of the existing overhead line (known as ZG route) between Denny North and Bonnybridge substations from 275kV to 400kV;
- Work at Bonnybridge 275kV Substation to terminate the new Bonnybridge to Glenmavis overhead line; and
- Moving the uprated 400kV circuit from the 275kV substation to the 400kV substation at Denny.
Above: Existing Bonnybridge 132kV and 275kV substations
We will also need to uprate some other overhead lines in the region from 275kV to 400kV, but these will be subject to a separate consultation in due course.
The new overhead line will be carried on lattice towers (pylons), made of galvanised steel. They are grey in colour and become duller in appearance after about 18 months.
The towers will have three arms on each side, and each arm will carry a set of conductors (wires).
This is because there will be a circuit on each side of the towers, and each circuit has three sets of wires.
The towers have a standard height of 46 metres, but can go up to 63 metres where required to ensure electrical safety clearance to the ground. They are usually about 300 metres apart, but the exact distance between them will vary depending on the landscape and any obstacles such as roads, rivers and railway lines.