Can the new line go underground?
Under the Electricity Act 1989, SPEN is required to consider technical, economic and environmental matters, and reach a balance between them.
High voltage, high capacity overhead lines are the proven economic and reliable choice for the bulk transmission of electricity throughout the world.
SPEN will consider undergrounding a 132kV, 275kV or 400kV overhead line, or section of that line, in particular circumstances where no suitable route for an overhead line can be identified. You can find out more about this in our Approach to Routeing and Environmental Impact Assessment document, which is available on our website.
The existing overhead line between Denny North and Bonnybridge substations was built in about 1975. We will need to replace the conductors (wires), and the insulators from which they are suspended.
We do not need to replace the existing L8 steel towers (pylons) as they are designed to carry circuits up to 400kV, but we may need to deviate the lines where they enter the substation sites.
Prior to uprating the overhead line, we may need to create temporary accesses to the towers and laydown /storage areas for our equipment, usually mid-way along the route.
Linesmen will climb each tower and the existing insulators will be unbolted and lowered to the ground using a tractor and winch, which will then lift the new insulators into position.
Following commissioning of the overhead line, all equipment and temporary access of construction areas will be removed with the land being reinstated to its former use/condition.