Delivering a 33/11 kV Grid Connection and Site‑Wide HV Network for One of Europe’s Largest Film Studios
Project Snapshot
| Client | Warner Bros. Studios, Leavesden, Hertfordshire |
| Project Value | £1.8 million |
| Duration | 13 months |
| Market Sector | Film & Media Production |
| Services Delivered | 33/11 kV grid connection, new primary substation, 11 kV site‑wide private network |
| Powersystems Fact | Powersystems celebrates 29 years as the UK’s first Independent Connection Provider (ICP) |
Client Background
Warner Bros. Studios Leavesden is one of Europe’s most advanced film production complexes — an 80‑hectare site housing world‑class facilities for major feature films, TV productions and the award‑winning Harry Potter Studio Tour.
The site includes:
- 50,000 m² of flexible production space
- One of Europe’s largest heated water tanks
- Workshops, offices, backlot sets and FX spaces
- A 32‑hectare exterior backlot with a 180° uninterrupted horizon
Originally an aircraft factory during WWII, the site has evolved into a global filmmaking hub used for major productions including Star Wars, Harry Potter, Sleepy Hollow and many more.
With continued growth, Warner Bros. required a significantly upgraded high‑voltage infrastructure to support studio expansion and ensure long‑term electrical resilience.
The Challenge
Warner Bros. required a new 33/11 kV connection and an extensive private HV network to support major site development, with:
- A tight programme aligned to construction and public‑opening deadlines
- Zero disruption to ongoing film production
- Full compliance with UK Power Networks (UKPN) and OFGEM standards
- A high‑capacity design able to support diverse loads, from sound stages to water tanks and specialist FX facilities
Our Engineering Solution
Powersystems was appointed to design, construct and commission a new Primary Substation and 33/11 kV grid connection, working under Competition in Connections (CiC) within the UKPN region.
The delivery included:
- New Primary Substation with dual 33 kV circuits
- 2 × 12.5 MVA 33/11 kV transformers
- 6‑panel 11 kV switchboard for UKPN and customer metered supplies
- Protection panels, battery chargers and telecontrol systems
- 1.9 km 33 kV grid route, including directional drilling beneath the A41
- 4–5 km of 11 kV cabling across the studio complex
- 14 × 1.5 MVA transformers with close‑coupled RMUs for distributed site loads
Powersystems also designed and constructed substation buildings, transformer compounds and all associated civil, mechanical and electrical infrastructure.
Project Process
- Design development in close liaison with UKPN and Utility Partnership Ltd
- Route surveys and civils works, including A41 directional drill
- Primary substation construction and building works
- Installation of dual 33 kV circuits and pilot cables
- Transformer and switchgear installation
- On‑site 11 kV network rollout across the 80‑hectare studio
- Testing, commissioning and UKPN witness approvals
- Integration with studio electrical systems
- Final handover ahead of opening deadlines
Project Facts & Figures
- 1.9 km 33 kV grid route
- Directional drill beneath the A41 trunk road
- 2 × 12.5 MVA 33/11 kV transformers
- 6‑panel 11 kV switchboard (UKPN + metered supplies)
- 33/11 kV protection panels and telecontrol
- Auxiliary 11/0.415 kV pad‑mount transformer
- 4–5 km of 11 kV private network cabling
- 14 × 1.5 MVA transformers with RMUs across the studio complex
- Extensive testing and commissioning of all HV assets
Technical Specifications
Primary Substation
- 33/11 kV transformers (2 × 12.5 MVA oil‑immersed)
- Neutral earthing reactors
- HV protection and control systems
- Battery chargers and auxiliary supplies
HV Equipment
- Hawker Siddeley ECLIPSE 11 kV indoor switchgear
- Dual 33 kV circuits from the primary substation
- Full suite of protection marshalling and termination works
Private 11 kV Network
- 4–5 km 11 kV cable installation
- 14 × 1.5 MVA 11/0.415 kV transformers
- Close‑coupled RMUs located throughout the site
Powersystems Partnerships
- Utility Partnership Ltd (UPL) — Managed delivery on behalf of Warner Bros.
- UK Power Networks (UKPN) — DNO for adoption and approval
- Specialist supply chain partners supporting civils, cabling, protection and commissioning
Key Risks & Mitigation
- Delivering within tight construction deadlines – Mitigation: Robust scheduling, phased commissioning, early design engagement.
- Working on a major live film production site – Mitigation: Strict access control, coordination with studio operations, low‑impact installation methods.
- Major off‑site works (A41 directional drilling) – Mitigation: Specialist contractors, detailed route planning and approvals.
- Coordination with UKPN under CiC – Mitigation: Proactive liaison, early technical submissions, joint inspections.
Environmental Considerations
- Efficient burying of HV circuits minimised landscape disruption
- Directional drilling reduced excavation footprint
- Modern transformers and HV equipment reduce long‑term electrical losses
- Reusing existing infrastructure corridors reduced material and civil requirements
Economic & Operational Benefits
- Increased capacity supports long‑term studio expansion
- Reliable HV supply for high‑demand sound stages and water tank operations
- Secure, resilient infrastructure enhances operational continuity
- Supports growth of the UK film industry through world‑class facilities
Future Prospects
Following the successful delivery of the HV upgrade, Powersystems is well‑positioned to support future expansion phases as Warner Bros. continues to grow its Leavesden operations.
Related Projects
- BESS & Grid Connections (33 kV and 132 kV)
- Industrial & Film‑Sector HV Infrastructure
- Private Network Refurbishments
- Large‑Scale Production Facility Upgrades
Planning a major film or media infrastructure project?
Contact Powersystems for expert support in grid connections, primary substations and private HV network design.