Circuit Main Shorting Device (CMSD) project – phase 3

  • Client: Kier
  • Project Type: New installation
  • Sector: Rail
  • Project Commenced: January 2020
  • Project Completed: December 2020
  • Location: Wessex and the South East
Installing the GRP ladder rack containment
RCU Electrician carrying out terminations in an interlock panel
External LC switchgear NCSD units

RCU Solutions was contracted by Kier on the Circuit Main Shorting Device (CMSD) project which installs a method of providing automatic secure and safe isolations to the DC traction power system, utilising switchgear with both local and remote control facilities.

RCU Solutions, supplied calibrated and tested plant and tools to complete the work and, essentially, provided Electrical Site Managers, Supervisors, Electricians and Electrical Mates to successfully implement this major project.

This new method creates a safer isolation process, improving the safety of operatives across Network Rail. CMSD significantly reduces the need to manually access the rail infrastructure to apply straps during isolations and eliminates the need for safety critical staff to work on track and around live 750v DC conductor rails. This new method also increases the length of the possession and window for works to be completed.


This third phase of CMSD involved RCU Solutions staff working at sites across Wessex and the South East, including Egham, Bracknell, Buckhurst, Upper Halliford, Witley, Whitmoor, Knowle, Hampton, Chiswick, Kempton Park, Ascot, Chertsey, Emmbrook, Glanty, New Eltham, Crayford, Woolwich Dockyard, Penge East and New Beckenham.

Work delivered by the RCU Solutions team included containment with specialist GRP ladder rack for DC cables, installation of the HSS and LCS, different types of switchgear including modular buildings and installation to existing substations.

In addition, RCU completed the installation, termination and testing of all control, indication, LV & DC cabling including final connections back to the remote terminal unit and assistance with the commissioning shifts. RCU staff also assisted with off-site preassembly of marshalling panels and interlock panels.

RCU Solutions successfully worked to tight programmes, possessions and deadlines in order to deliver these works safely, efficiently and to a high electrical standard.

Using calibrated and tested correct plant and tools to complete the work
Individual HSS NSCD switchgear units installed within substation on this site
GRP Ladder rack containment for DC cables

The scope of works completed by RCU Solutions included:

  • Supplying calibrated and tested plant and tools
  • Providing highly competent team members
  • Cable pulling, cable dressing, cable terminations, all control and indication wiring/LV cabling/ DC cabling/SCADA
  • Building of marshalling panels and boxes
  • Containment with specialist GRP ladder rack for DC cables
  • Installation, termination and testing of all control, indication, LV & DC cabling
  • Installation of the HSS and LCS, different types of switchgear
  • Installation to existing substations

“RCU solutions has the required skilled and experienced staff with the required competences to work in substations and on track. The interesting innovative element of this project is the safety element. The CMSD project will vastly reduce accidents across the railway infrastructure. Local control panels enable the operator easy access with the option to open and close NSCD switchgear remotely without accessing the substation.”

External GRP containment
GRP DC containment here with cable tray for SWA cables on cable tray above for compound lighting
NSCD switchgear within a new module

RCU Solutions worked well in partnership with Kier Group who said that we kept their best interests in mind throughout the whole project. We have continued to work with Kier ever since.