London Power Tunnels 2London Power Tunnels 2

Project name
Temporary Ventilation National Grid London Power Tunnels Ph 2 Package 2
Industry category
Power Cable Tunnel Infrastructure
Fan model
2x ZVN 1-7-30/2, 2X ZVN 1-9-37/2, 2X ZVN 1-9-45/2, 3X ZVN 1-9-55/2, 1X ZVN 1-7-30/2
Fan type
Unidirectional Axial fans
Fan impeller diameter
700 mm & 900 mm
5 Axial fans plus power and control cabinets
Total installed power
419 kW


The project: National Grid is building a new cable tunnel, 32.5km in length, between Wimbledon and Crayford.
In Spring 2020 National Grid embarked upon a six-year, £1 billion project, to rewire South London via deep underground tunnels. This vital work will help keep Londoners connected to safe and reliable electricity supplies.
In total 32.5km of 3m diameter tunnels are being constructed deep below the road network between Wimbledon and Crayford, which will carry high voltage electricity cables.

Scope of Supply: Zitrón’s scope of works for the project compromised the design, delivery, installation, and commissioning of the Temporary ventilation  fans,  the cabinets, the design of a vertical ducting, and thousands of meters of ducting both circular and oval design.

Several newness compared to traditional Temporary ventilation are as follow:

  • The fans include several control measures in terms of motor temperature sensors and vibration sensors for the control of the performance and wellness of the equipment.
  • The fans include measurement of flow and pressure installed in the fan itself.
  • The newest accessory is the Ventilation on Demand system. A system specifically designed for measuring the airflow delivered at the tunnel front of work (TBM located) and implementing in the Control cabinet the desired minimum speed, the fan station auto regulates to provide always the required airflow

The installation and commissioning of the entire ventilation system to reduce as much as possible the Construction operation was one of the project keys to complete it successfully.

Hatfield Tunnel
HS2 C1