* Isle of Grain - Medway Kent

* Stratford-London

* South Croydon

* Harlsden/Willsden

Isle of Grain-Medway Kent

  • substation
    Isle of Grain Sub station
  • Sub station
Isle of Grain Sub station

Client: FOC- National Grid

Project- 400,000V AC DTS monitoring

Special Resources - confined space including Rescue Team, BESC

SNS were tasked to install, terminate and test a Distributed Temperature Sensing fibre system from The Isle of Grain to Chetney Marshes via an air cooled tunnel 50m under the river Medway.

Due to the remote locations of the sites, the specialized environment of working and stringent requirements of National Grid, this proved an extremely difficult project to plan and implement, in particualar Risk assessement and method statements, as they had to be clinical and precise as the 400,000V cabling was to remain live within the tunnels.

SNS's team:  1 lead engineer, 6 installation engineers and 6 designated safety officers, 3 at each head house to the tunnel system.

The tunnel system was twin bore with access to 1 bore only at any one time. The DTS fibre systems consist of phase cable mounted fibre and a crown mount to each bore, however drilling of the tunnel structure was forbidden and SNS designed a bespoke cable clamp system to allow the crown fibre to be fixed to the existing leaky feeder mounts.  As a result of smooth progress to the project we were tasked with installing additional containment to the riser shafts and install addtional free issue communication fibres.