Published: Fri 21 Mar 2025
IET experts respond to Heathrow closure due to substation fire
Stephanie Baxter, Head of Policy at the Institution of Engineering and Technology said:
"The IET welcomes the £600 million pledged to train 60,000 more engineers, electricians and construction workers. These skilled workers will be essential if the government is to meet its target of delivering 1.5 million new homes by the end of this parliament, along with its Plan for Change.
"The ongoing shortage of skilled engineers and technicians in the UK is impeding engineering sectors, such as construction and manufacturing, from capitalising on innovations, holding back productivity and risks the UK falling behind international competitors. By better preparing young people across the country with the skills to fill shortages in these crucial growth sectors, the government can support families and deliver long-term, sustainable economic growth across the whole of the UK.
"Whilst getting more people into the skills pipeline is crucial, government must also take a joined-up, whole systems approach by working closely with industry and academia to ensure that funding and support is available to businesses, particularly SMEs, to upskill and reskill existing workers throughout their careers.
"For example, access to agile short courses in new technologies such as Digital Twins and AI will ensure that the UK workforce remains adaptive to and able to capitalise on rapidly changing technologies and best practices."
Mark Coles, Head of Technical Regulations at the Institution of Engineering and Technology said:
“Electrical substations are a critical part of the electrical distribution system. Power stations generate electricity which is then distributed across the country at high voltage. Substations connect the power station to the distribution network and then, at the other end, substations connect the distribution network to where power is needed.
“Substations are electro-mechanical installations. Transformers are used in substations to raise the voltage for distribution across long distances and then to lower the voltage to a more usable level for use in electrical installations in, for example, commercial buildings and homes.
“The law, that is the Electricity at Work Regulations 1989, requires that all electrical installations are maintained in order to be safe for continued use. This applies to electrical substations which should be regularly checked. As part of this, records will have been kept of testing and inspection and, for example, thermal imaging cameras will have been used to make sure connections aren’t overheating. Maintenance work will look to diagnose possible failures of equipment and then any required repair work can be carried out. For this situation, the investigation will look at the history of the equipment, such as the manufacturer’s data from when it was manufactured. The investigation will be far reaching, and every aspect will be looked at to ascertain what has happened. It is very unusual for one incident to cause the entire shut down of an entire site like Heathrow airport.”
Professor John Loughhead CB OBE CEng, Fellow and electrical engineering expert at the Institution of Engineering and Technology, said:
“An electrical substation is where high voltage electricity from the national grid is transformed to lower voltages and distributed to users, and contains various switches and safety devices. It is therefore the supply point for users. It is surprising that, as a part of our national critical infrastructure, Heathrow does not have an alternative supply point in case of accidents like this.
“Fires do occasionally, but not frequently, occur at substations and can have various causes - from electrical short circuits to failures in transformers. It's not stated what caused this one and it may take a while for what happened to be determined. A fire within a substation area can damage switchgear, transformers, measurement and control equipment, and cables. Fires are not unprecedented but are also not frequent. If they damage equipment any user 'downstream' of the substation will lose all power. In this case, Heathrow just happens to be the key user, although it seems other users are also affected.
“To restore power, supply companies may be able to route power to Heathrow through an alternative circuit, although it seems this is not easily done or may not be possible, or any damaged equipment will need to be replaced to get the substation back into service. To determine the original cause will mean examination of the damaged equipment and operating records to judge the sequence of events leading to the fire which may be obvious or require some time to work out.”
Graham Kenyon, an electrical engineering expert at the Institution of Engineering and Technology, said:
“An electrical substation like this takes very high voltage power from the national grid, and switches it to various transformers, distribution protection equipment, and other substations that eventually supplies end users such as homes, businesses and airports with power.
“This particular substation is a major distribution centre for the national grid, in a very populated area of the city. In addition to Heathrow Airport and local residences and businesses, there is a significant amount of commercial and industrial power use in that area.
“It’s too early to provide a definite answer on what has happened here. Heathrow airport has multiple supplies from the national grid and means of diverting power if it is safe to do so. Power in an airport is required for safety equipment for flight operations and safety and security of the public in and around airport terminals.
“The Civil Aviation Authority has rules that govern the impact of power loss on airport operations, which includes consideration as to how long the loss of some, or all, power at an airport is expected to last. Airport operations can also be affected by the consequences of a major incident in the vicinity of the airfield or flight paths, for example smoke affecting flights.”
Professor Gareth Taylor, Fellow at the Institution of Engineering and Technology, said:
“It is highly unusual that such a single substation outage due to a fire hazard has led to a complete blackout of a critical load such as Heathrow airport. I expect that it is likely that the overall blackout and power outage to Heathrow will be a complex set of circumstances and series of faults – this could be similar to the unprecedented major blackout and power outage of London and London Underground in 2003.
“Reports suggest the fire started by a major fault with a voltage transformer in the substation, but the cause of the fire will be looked at and confirmed by a detailed forensic investigation.”
Mark Aizlewood, member of the IET’s Aerospace Technical Network Committee and Head of Aerospace Integration Research Centre and Programmes at Cranfield University, said:
“The aviation industry is at its best during a crisis. It really comes together, and companies that day-to-day compete to be the best airline will work together with the airport and businesses to resolve from the situation as quick as possible. Airports are like communities, where everyone works together as quick as we can.
“At this stage we don’t really know what the impact will be. If they will be back on at midnight we should have flights back tomorrow, then it’s a question of how long it will take to bring all services back online to function fully again. At the moment the airport is unable to operate and it will come back online as safely and swiftly as possible. The industry really prides itself on safety so there will not be a rush to do so in an unsafe manner.
“It’s too hard to say how long it will take to clear the backlog; some flights will be cancelled, some rearranged, and so it’s difficult to know the impact at this time.
“There was a similar level of disruption with the Gatwick drone sighting a few years ago; at that point aircraft were unable to land for an extended period, this time aircraft already airborne had to divert to other airports or to return. Does the UK need to have lots of spare capacity to deal with these major events? That would not seem sensible, as these events do occur, but they are not regular, so we do not need to have more runways to cater for them.
“Everyone will be working as a team to get Heathrow back online; this is a strength of aviation and something working in the industry I feel proud to be a part of.”
Stuart Mortimore, a Fellow of the Institution of Engineering and Technology and a fire and forensic investigations expert, said:
“The initial press reports suggest that the fire is due to an electrical fault that developed within an oil filled transformer at the substation. Such a failure would have caused severe and widespread electrical arcing activity – "sparking" – which would have ignited the oil as it was ejected forcefully from the transformer. This would have resulted in a large fire that was difficult to extinguish.
“The damage caused makes it unlikely that much useful physical evidence will remain. The investigation is therefore likely to concentrate on the operation of the transformer and its maintenance. Specifically, if it had an on-load tap changer - a complicated switch that can automatically change the output voltage while supplying electricity - that was operating at the time of the fire, this could point to a fault with the switch.
“Maintenance checks will be undertaken to see if periodic oil tests had shown any signs of leakage from the transformer that might have caused electrical components within the transformer to become uncovered, or whether the oil was degrading with age that meant it failed to insulate components adequately. Either of these problems could have caused a loss of insulation, which precipitated electrical sparking and thus the incident."
ENDS
Notes to Editors
About the IET
- We inspire, inform and influence the global engineering community to engineer a better world.
- We are a diverse home for engineering and technology intelligence throughout the world. This breadth and depth means we are uniquely placed to help the sector progress society.
- We want to build the profile of engineering and technology to change outdated perceptions and tackle the skills gap. This includes encouraging more women to become engineers and growing the number of engineering apprentices.
- Interview opportunities are available with our spokespeople from a range of engineering and technology disciplines including cyber-security, energy, engineering skills, innovation, manufacturing, technology, transport and diversity in engineering.
- For more information, visit org
- Follow the IET on X.
Media enquiries to:
Rebecca Gillick
External Communications Manager
E: rgillick@theiet.org
Jack Tappin
Senior Communications Executive
E: JackTappin@theiet.org
We’re upgrading our systems, and this includes changes to our customer and member account log in, MyIET. It’s part of our big picture plan to deliver a great experience for you and our wider engineering community.
Whilst most of our websites remain available for browsing, it will not be possible to log in to purchase products or access services from Thursday, 17 April to Wednesday, 30 April 2025. Our Member Relations team is here to help and for many of our services, including processing payments or orders, we’ll be able to support you over the phone on +44 (0)1438 765678 or email via membership@theiet.org.
We apologise for any inconvenience this may cause and thank you for your understanding.
For further information related to specific products and services, please visit our FAQs webpage.