Introduction: Develop a new technique and associated equipment which will allow National Grid's Overhead Lines (OHL) suppliers to replace fibre optic cable wrapped on the earthwire with an Optical Ground Wire (OPGW) using a live technique (i.e both circuits live). This technique will eliminate the need for installing temporary fibre diversions (needed to keep telecoms services going during the work) and the need for transmission outages as the work can be carried out live. The process will reduce scheme costs, reduce the requirement for optical and transmission outages, enable the work to be carried out in all environments and be less damaging to the environment. Capital works will also benefit because the method will lower the risks which normally have to be mitigated in the larger capital scheme ultimately lowering overall scheme costs.

Objectives: The project has defined the following objectives:

• Replacement of wrapped earthwire without use of temporary bypasses.

• System can be deployed without requiring transmission outages (i.e. with the HV circuits live).

• Significant reduction in the number of optical outages (reducing risk to customers).

• Can be deployed over difficult terrains where there is no method at present.