62,000 customers restored and 4,900 still without power by 0600

A fire at the North Hyde substation in West London damaged equipment and led to a loss of power supply in the area, National Grid said. In an update timed at 7am on 21 March, the operator reported that power had been restored to 62,000 customers as of 0600, with 4,900 still without power.

National Grid said it was working alongside SSEN Distribution, the distribution network operator for the area, to reconnect affected domestic customers, and that restoration efforts would continue that morning. The fire also affected supplies connected to the substation used by Heathrow airport.

By 2pm on 21 March, National Grid said the network had been reconfigured in partnership with SSEN Distribution to restore all customers impacted, including the ability to resupply the parts of Heathrow airport connected to North Hyde. The company described this as an interim solution while further work is carried out at North Hyde to return the substation and its network to normal operation.

At 6am on 22 March, National Grid said power supplies had been restored to all customers connected to the North Hyde substation, including Heathrow, allowing operations to resume at the airport. It said it was implementing measures to help further improve the resilience levels of its network. At 3.30pm the same day, the company welcomed the National Energy System Operator's investigation into the events and said it would work closely with all parties involved to understand the cause.

The cause of the fire has not been reported. National Grid said it was working with the Government, Heathrow and the police to understand it.

Why it matters for households

The incident shows how a single substation fire can interrupt supply to tens of thousands of homes and to a major airport at the same time. For households in the affected part of West London, the sequence reported by National Grid was a staged restoration: 62,000 customers back by 0600 on 21 March, a reconfiguration of the network later that day to reach all impacted customers, and full restoration for customers connected to North Hyde by 0600 on 22 March. The company has said further work at the substation is needed to return it and the network to normal operation, and that it is bringing in measures to improve network resilience.

Households can report a loss of supply to their distribution network operator by calling 105, as set out in our guide to reporting a loss of electricity. Our guide to how long until the electricity comes back explains how restoration typically proceeds after an incident of this kind, and our page on storms and the electricity network covers how networks are affected and what happens during repairs. The power cuts hub collects these guides.

What happens next

The National Energy System Operator is investigating the power loss impacting Heathrow, and National Grid has said it will work closely with all parties involved to understand the cause. National Grid has also said it is carrying out further work at North Hyde to return the substation and its network to normal operation, and is implementing measures to improve the resilience of its network. No dates for the completion of that work or for the investigation have been reported.