Power upgrade works in Mayfair

UK Power Networks owns and maintains the electricity network delivering power to your area. We are currently undertaking power upgrade works in Mayfair to strengthen the resilience of the local electricity network.    

The existing infrastructure supplies electricity to local businesses and thousands of homes. These upgrades will help ensure a reliable supply of power for the area now and into the future. 

The power upgrade works include two separate projects:

• Installation of a new electricity cable between Seymour Place and Duke Street Substation
• Upgrades to equipment at Duke Street Substation

We are working closely with Westminster City Council to agree traffic management and logistics plans, with the aim of keeping disruption to a minimum and to managing the impacts of the works on the local area.

The works will be carried out in stages. We will keep residents, businesses and organisations informed throughout, with information being made available online, and regular updates issued so people know what to expect and when throughout the programme.

The cable works between Duke Street Substation and Seymour Place will upgrade an existing circuit (Lodge Road to Carnaby) that carries power across London.

The new cable route will replace an existing section of the network that needs upgrading - around 1.3 kilometres (km) of cable will be installed, with work being carried out in phases to minimise disruption along the route. Our teams will work at multiple locations along the route simultaneously, and we will complete our works as quickly as is safely possible to reduce disruption.  

We will be excavating short trenches to lay pipework (ducts), then returning to open excavations at intervals along the route to pull through and connect the cables. 

Our work should have no impact on your electricity supply. We plan to begin work in Spring 2026 and will complete the cable project by Spring 2027.

Duke Street substation is located beneath Brown Hart Gardens on Duke Street, Mayfair (W1K 6WP), and houses three transformers that now need to be upgraded.

The substation sits within a Grade II listed building owned by the Grosvenor Estate, originally built to house a power station and generator hall. All the works we plan to carry out will have full regard for the building’s listed status, ensuring the historic structure is protected and preserved.

Each transformer weighs approximately 80 tonnes and stands around four metres high – measuring about five metres in length and three metres wide. Because of their size and location, the transformers cannot be moved in one piece, so we will need to dismantle them underground and remove in sections. This means that most of the work will take place below ground and won’t be visible from the street – this will also help minimise disruption.

We plan to start setting up work on site from July 2026 and anticipate that it will take around three years replace of all three transformers. We will dismantle, remove and replace each transformer one at a time. The vast majority of our work will be undertaken out of sight of the general public, and the only visible work for most of the project will be members of the team entering and exiting the substation. Only the transformer removal and replacement will be seen from the street, and this work will form a small part of the three year programme.

Work is due to take place in stages in the roads listed in the table below.

As well as using advance warning signs, we will write to residents with further details before work is due to start in each new area. Safety is our priority and in consultation with the local highways authority, traffic management measures will be in place as we progress along the cable route.

Work will progress in stages, with traffic management and safety barriers being moved along the route in sequence with our working area. We apologise for any inconvenience caused and aim to complete the work as safely and as efficiently as possible to minimise the impact.