Supply security is rated as the second most important element of our service by our customers after price stability and we invest heavily in excelling in this area.
We measure our reliability in Customer Minutes Lost (CMLs). This is the average minutes of service disconnection time per customer in a year. Last year our CMLs were just eight. This is around ten times better than the ‘Big Six’ UK electricity distributers which in 2015-2016 averaged 74 CMLs*.
Our supply margin (plant capacity v peak demand), an important consideration for supply security, is also greater than the UK’s which aims for a margin of around 10% above peak demand. Here, with three supply links to France, across two diverse routes, giving us access to 190MW of imported power against a record demand of 161MW in February 2012, our margin is around 20% even without taking account our on-Island generation assets at La Collette Power Station and Queen’s Road.
We have enhanced security this year with the commissioning of the ‘black start’ 5.5MW Diesel 5 Sulzer generator at La Collette. We work to an adapted ‘N minus 1’ standard. This means, we seek to maintain supplies during the failure of the largest component in the system and we strive to minimise the risk of such an asset failure and we ensure we are well prepared to restore supplies quickly when a failure does occur.
*Source: Ofgem RIIO ED1 Annual Report 2015-166-7