The tunnels operated by EDF Energy and National Grid require specialist ventilation to remove the heat produced by the cables and smoke clearance if hit by fire.
Allan Hurdle, managing director of Elta Fans, said: “The fans needed for the tunnel sites in London need to remove hot smoke in the event of an emergency and must be constructed in such a way so that they do not ignite any gas that may be present.
“Acoustic lagging is a specific feature of these applications as sound levels are important as the main vent shafts are in residential areas.”
The company has also just delivered temporary ventilation equipment to contractor Balfour Beatty which is working on the Hindhead bypass on behalf of the Highways Agency.
The 1.4 metre fans will extract machinery fumes and dust to provide fresh air during construction work.