Group CEO John Pettigrew also denied claims he was on holiday at the time of the incident and added the “UK is not Argentina” after comparisons with the country, which experienced a blackout earlier this year following a massive electrical failure that left tens of millions of people in the dark.
He said the grid operator has been doing “everything in our power” to understand the sequence of events and consequences of the incident, which forced trains to a standstill, knocked out traffic lights and affected some hospital services and airports.
It came after two power plants – one gas and one wind farm – accounting for around 5% of the UK’s electricity needs, failed almost simultaneously.
Business Secretary Andrea Leadsom announced an investigation into the power cut and will also be commissioning the government’s Energy Emergencies Executive Committee to consider the incident.
“System did the job it was designed to do”
Mr Pettigrew said the system “did the job that it was designed to do”, with power restored within 15 minutes, adding the distribution network operators (DNOs) had all restored electricity to their own customers within 45 minutes.
He also admitted the timing of the power cut at 4.50pm on a Friday afternoon in August, “when people are trying to get home to their families and friends after a hard week at work is one of the worst”.
The chief executive added: “Since that partial power cut, thousands of colleagues across the industry have been working hard to ensure the system is robust and to understand exactly what happened, and what we should do differently in the future.
“The whole UK energy industry needs to understand the causes of this power cut and also why it was able to create such significant disruption to services across Great Britain, particularly the transport network.
“Nevertheless we shouldn’t be too hasty to declare a complete failure of our current system. Whilst this event was due to a rare and exceptional combination of circumstances, we were able to restore power within 15 minutes.”
“UK is not Argentina”
He added since an incident on this scale has not happened in the UK since 2008 and because it is so rare, “it becomes so widely talked about”.
Mr Pettigrew went on: “Contrary to the comparisons in some parts, the UK is not Argentina and even after Friday’s events, we have statistically one of the most reliable energy networks not only in Europe but anywhere in the world.
“This is the result of the energy industry investing £100bn in distribution and transmission networks since 1990. In the past six years alone, National Grid has invested £10bn in improving the security, integrity and carbon performance of UK energy supply markets. Power cuts are actually 60% less frequent than they were when I started working at National Grid back in 1991.
“We are certain this was a result of a freak coincidence and not a cyber-attack. While we must not be complacent and must continue to be vigilant, our investments in cyber security defences provide a silent shield to UK power supplies.”
He said National Grid is already “well into our own international investigations” looking at the performance of the networks and the actions of the Electricity System Operator (ESO) and will be reporting the findings to Ofgem and government by the end of this week.
“No near misses or early warning signs of similar incidents”
In a separate statement, the grid operator also refuted media reports claiming there have been blackout “near misses” prior to the power cut last Friday.
In a statement, National Grid said: “Contrary to media reports, there have been no near misses nor early warning signs of incidents similar to last Friday’s power cuts. This was a highly unusual event, without precedent in the past 10 years.
“We work with Ofgem to set the agreed limits of frequency of electricity output to keep the whole system safe and the lights on. All the time until Friday’s events, the system has remained within safe limits.”
“We can and must learn from Friday’s events – however rare their occurrence – as National Grid and as an energy industry.”
Ofgem sets timeline for National Grid report
Ofgem has set out a timeline for National Grid ESO to report to the regulator on the power cut, with an “urgent” interim report expected by Friday, 16th August and a final technical report by Friday, 6th September.