Substation fire that shut down Heathrow was caused by moisture flagged as a problem SEVEN YEARS earlier but left unrepaired

The Heathrow airport, which closed the airport for a day, was first caused by a problem seven years ago, but was caused by an irreparable moisture.

Energy Watchdog Ofgem launched an investigation after seeing that a new report in Hayes in Hayes in Western London on March 20 was caused by a prevented technical error.

More than 270,000 airlines travelers broke down with a fire, which forced the UK’s most intense airport to close for almost a day.

The next power outage led to the loss of power of 71,655 domestic and commercial customers and a ‘full resource loss’ part of the Heathrow Airport’s internal electricity distribution network.

The report by the National Energy System Operator (Neso) said that in July 2018 North Hyde Transformer in Western London, there was ‘high moisture reading’ in the oil samples in the center of transformer, but there was no action to replace electrical isolators known as horoscopes.

In 2022, the decision of ‘postponement of the basic care’ in the transformer center, that is, the problem ‘has not been added’ went, that is, the electrical insulators known as horoscopes were not changed.

On Wednesday, Ofgem, Neso examination based on the findings of the National Network Electrical Transmission (Nget) said he opened an official executive investigation.

Neso report, one of the transformers in the fire ‘probably the moisture that caused the short circuit of moisture that caused a’ ‘disaster failure’, he said.

On March 21, Heathrow dived into chaos after forcing a destructive electrical fire to close the most intense airport of England for the day

In the report, a review by National Grid in 2022, the fire suppression system in the North Hyde region was ‘not working’, and another assessment in July 2024 was still ‘non -service’.

Due to the fire that started late night the night before, he did not fly at the West London Airport until 18.00 on March 21.

Ofgem Infrastructure General Manager Akshay Kaul said: ‘North Hyde transformer central fire caused global deterioration, affected thousands of local customers and stressed the importance of investment in our energy infrastructure.

“ As a result of the findings of the report, we have started an investigation into the national network electricity transmission.

“ We also made an independent control of the most critical assets.

Ofgem will also examine the event and the causes more and will take more action.

“ We expect energy companies to properly protect their equipment and networks to prevent such events.

‘When there is evidence that they are not, we will take action and take full account of companies.

‘Britain has one of the most reliable energy systems in the world, and fortunately, events like this are rare. In order to maintain this flexibility, we should continue to invest in the system. ‘

The results obtained from the investigation of Ofgem may find any violations or harmony action to adapt to companies as well as potential contributions to the voluntary compensation fund, penalties and license cancellation.

Neso report published on Wednesday and appointed by Energy Secretary Ed Miliband read the following: ‘In July 2018 oil samples received a high moisture reading in one of the SGT3s (transformer) signs.

Burning North Hyde Electrical Transformer Center causing a power outage in Heathrow

Firefighters are spraying foam in the North Hyde Transformer Center for burning for March 21

After the fire came out, the passengers were stranded for hours. Inspectors say that the fire is not a suspicious reason

‘According to the relevant guide of national network electricity transmission, such readings indicate that a close error and the horoscope should be changed.

‘Reading was recorded in the online system of national network electricity transmission, no mitigation in accordance with the seriousness.

‘On -site controls were not effective and then he could not determine that the action was not done according to high moisture reading.

‘This also includes an opportunity to postpone the basic care of SGT3 in 2022. Therefore, the problem was not accepted. ‘

The report continued: ‘July 2024 fire risk assessment, if a fire is initiated to any of the three supergrid transformers,’ would not be suppressed properly ‘he said.

As a result, a high priority action was created in the pump of the water fog system to be served and protected.

`This action remained extraordinary during the incident in March 2025.

‘National grilled electricity transmission, until October 2025, the fire suppression system is planning a combination of changing and renovation of the system said.’

Neso review also found that the design and configuration of Heathrow’s internal power network, only one of the three supply points’ loss of ‘loss of power to operational critical systems, which would lead to suspended operations for an important period’.

The report plans to respond to such an event, including the restructuring of the network, which would last for about 10 to 12 hours, but the loss of a supply point was not considered as a possible scenario by the Heathrow Airport Limited ‘due to the loss of flexibility of a wider network.

‘This meant that the internal electric distribution network was not designed or configured to benefit from having more than one supply point to provide rapid recovery after such a loss.’

The fire caused the airport to be closed on March 21 at 18.00, but a report found that electricity was restored to the terminals hours ago (in the picture: a sign at the underground station of Heathrow Airport on March 21)

Energy Minister Michael Shanks said: ‘I’m deeply worried that the risks are not handled by the national network electricity transmission, the key operator of our electrical system.

Nget’s own guidance is clear. Based on the high moisture samples that Nget 2018 received, the asset should be out of service until decreasing actions are applied or carefully monitored until the asset is changed. ‘

Mr. Shanks added: ‘I talked to Nget this morning and explained that these findings were unacceptable and that the maintenance of critical assets should be given to the appropriate priority. Fire extinguishing systems should not be left as soon as they work. ‘

He continued: ‘I would like to say that the Great Britain continues to have a flexible energy network, and although such events are rare, it is important to learn the lessons to be maintained and, if possible, to improve our flexibility.’

Cabinet Minister Ed Miliband said: ‘The report is deeply interested because the known risks are not handled by the national network electricity transmission, and ofgem has opened an official execution investigation to take into account the possible undergraduate violations of the electrical system in North Hyde.

“ There are wider lessons to learn from this event. My department, which works throughout the government, will urgently deal with the findings and suggestions determined by Neso and will publish a timely response to the report. ‘

A Heathrow spokesman said: ‘Heathrow welcomes this report, which sheds light on the external power supply error that forces the closure of the airport on March 21st.

‘A combination of the old regulation, inadequate security mechanisms and the lack of the national Grid’s infrastructure caused this disaster.

“ We expect the national network to carefully think about which steps they can take to ensure that it is not repeated.

‘Former Cabinet Minister Ruth Kelly, led by our own review, detected key areas for improvement and work.

Heathrow is the largest airport in Europe with more than 83.9 million passengers traveling at terminals in 2024.

A national grille spokesman said: ‘As Neso’s report appeared, we have one of the most reliable networks in the world in Great Britain, and this is rare.

‘National Grid’ has a comprehensive asset inspection and maintenance program, and since the fire we have done more operations. This includes the end -to -end review of our oil sampling process and the further development of fire risk assessments in all operational areas, and re -testing the flexibility of transformer centers serving strategic infrastructure.

“ We fully support the suggestions in the report and we are determined to work with Neso and others to implement them. We will cooperate with ofgem’s investigation.

‘There are important lessons to learn about the flexibility and increasing need for coordination between sectors, and we are looking forward to working with the government, regulators and industry partners to take these suggestions forward.’

Heathrow spokesman, the national network ‘protection of the infrastructure’ ‘he said.

Sözcü said: ‘Heathrow welcomes this report, which sheds light on the external power supply error that pushes the closure of the airport on March 21st.

‘A combination of the old regulation, inadequate security mechanisms and the absence of the infrastructure of the National Grid led to this disaster power outage.

“ We expect the national network to carefully think about which steps they can take to ensure that it is not repeated.

‘Former Cabinet Minister Ruth Kelly, led by our own review, detected key areas for improvement and work.