NIA SSEN 0035: Informed Lightning Protection

Key Activities

Lightning strikes are known to cause a significant number of supply interruptions to our customers. In our Scottish Network, lighting strikes are the second highest cause of customer interruptions and minutes lost, and in our Southern Network it is the fifth highest cause. Therefore, there is a need to reduce the impact that lighting related faults have on our customers.

Expected Benefits

This project is now complete. The project has proven that customer supply interruptions caused by lighting related faults can be significantly reduced by installing surge arresters in strategic locations.

Progress

The project installed c150 surge arresters installed within SEPD and 300 in SHEPD on circuits where lightning faults had occurred frequently. These circuits have experienced a 50% improvement in Interruptions Incentive Scheme (IIS) costs due to lightning vs the previous 3 years where no lightning protection had been installed, and a 76% improvement when comparing against the previous 10 years. This has been calculated by measuring lightning related IIS costs for the years before and after lightning protection devices were installed. However, even with a 50% improvement in IIS costs, the payback period is 16 years, which is about the expected lifespan of the surge arresters. It is probably unfair to compare IIS costs to the previous 10 years as many circuits have been changed over the time (e.g. back-fed to reduce IIS impact). It is clear that lightning protection can play a role for reducing IIS costs, but it needs to be cheaper, have a longer lifespan or be more strategically located to have a significant benefit. With this in mind, we do have plans to roll out lightning protection more strategically to improve the benefits case.