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Network reliability

Performance summary 2017/2018

Network performance
45%
reduction of customer minutes lost
88.5%
of customers had their power restored within one hour of a high voltage fault
Overview of outputs
11
Improve network performance by the end of RIIO-ED1 so that, on average, customers will have 16% fewer power cuts and have their electricity supplies restored 23% quicker.(See note 1 below).
Customer interruptions have reduced by 27% and customer minutes lost have reduced by 45% from the underlying performance benchmark calculated for 2011/12.
12
Make sure that at least 85% of customers have their power restored within an hour of a high voltage fault happening.(See note 2 below)
88.49% of customers had their power restored within one hour of a high voltage fault.

Guaranteed Standards of Performance (GSOPs)
99%
reduction of the number of customers left without electricity for more than 12 hours
Overview of outputs
13
Reduce by 20% the number of customers experiencing a power cut which lasts for 12 hours or more.(See note 1 below).
The number of customers without electricity for more than 12 hours (where the GSOP applied) was 52, an improvement of over 99% on our 2012/13 benchmark performance. Customers received a set payment where we failed to achieve the GSOP.
14
Achieve no failures on all other GSOPs.(See note 2)
We had no failures against most GSOP categories. However, we failed to notify eight customers of planned interruptions to their electricity supply and failed to meet the standard for restoring supply following a main fuse failure for one customer.

Worst served customers
10,453
customers will be helped by projects put in place to reduce the number of worst served customers
Overview of outputs
15
Reduce by 20% the number of customers classified as worst served.(See note 1 below).
To date, projects to reduce the number of worst served customers have been put in place for 10,453 customers. Our target for the whole of RIIO-ED1 was 6,812 customers.

Making our network more resilient
48
substations have had flood defences installed
777km
of trees cleared from overhead lines
Overview of outputs
16
Apply flood defences to 75 substations, reducing the risk of both damage to equipment and power cuts due to flooding.(See note 1 below).
To date we have installed flood defences at 48 substations. We are on track to achieve our RIIO-ED1 targets.
17
Speed up the programme of tree clearance (specifically related to storm resilience) by 40%, with the aim of clearing 700km of overhead lines per year (delivering the programme five years earlier than suggested by Government guidelines).(See note 1 below)
We beat the tougher targets we set ourselves, clearing trees from 777km of overhead lines in 2017/18.
18
Improve substation battery life to last for 72 hours if there is a major, network-wide power loss.(See note 1 below)
All programmes are ahead of plan.
Protection batteries – 50% of eight-year programme complete.
SCADA batteries – 50% of eight-year programme complete.
Telecommunications sites – 90% of eight-year programme complete.

Note 1: This target is for the full eight-year RIIO-ED1 period, not for each separate year.

Note 2: This target is for each year of RIIO-ED1.

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