Project Specifications

About Project

Sunville Rail were contracted to build a new brick built substation at the Hollingbourne site.

Project Overview

The scope of this project covered the DC switchgear renewal at 2 substations located in the South East Territory – (Harrietsham S/S, Hollingbourne S/S).

The particulars of the design and installation related to the Network Rail DC Switchgear Renewal Project for 750V DC switchgear, BBK850 phase C.

The new switchgear replaced obsolete 1950’s Bertram Thomas HSE and British Thompson Houston (BTH) RLR151 circuit breakers.

The general scope of work required at each of the 2 sites were as follows:

  • Installation and commission new building for DC switchgear
  • Install and commission new DC switchgear in the new building
  • Install and commission new indoor 50V battery charger
  • Install and commission LV domestic installation and services in the new building
  • (lighting, standby lighting and personnel and anti-con heating)
  • Install and commission positive cabling from the main DC contractor
  • Install and commission new marshalling cabinet in new DC building
  • Relocation of the existing pilot cable from existing building to new DC building
  • Install and commission new pilot cable and box in new DC building
  • Removal of the existing indoor 50V battery charger
  • Removal of the existing DC switchgear

Hollingbourne S/S only:

  • Removal of the existing HV switchgear
  • Removal of the existing transformer rectifier unit from the substation building
  • Removal of the existing marshalling cabinet in substation building at
  • Construction of new brick built building to house new equipment
  • Demolition of the existing substation building
  • Relocate and commission the existing Transmitton RTU to existing HV switchgear building


  • Demolition of existing DC Hut

Sunville Rail was contracted at both sites, with the primary goal to build a new brick built substation at the Hollingbourne site, including associated security doors, safe access, cable and route works.

Sunville Rail was engaged early on the project to liaise with the civils design team, to enable a smooth transition from design approval to construction.

Due to issues with commissioning dates, Sunville Rail was given the challenge of completing the New Building in an extremely ambitious 29-day construction period.

Sunville Rails multi-disciplined workforce worked back to back shifts and completed the civil works within the programme timescales and within budget. Below are examples of the construction stages of the project.

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