London Underground Infastructure

ISS successfully manage and deliver a variety of different contracts and projects, ranging in size and complexity on various rail infrastructures nationwide. ISS have vast experience working on the London Underground Infrastructure, Network Rail Infrastructure and Tram Networks.

London Underground Infastructure

ISS have significant experience in upgrading existing, and the installation and commissioning of new 415V, 11kV and 22kV AC Systems and DC Systems across the London Underground Network. ISS works include the supply, installation and commissioning of LV switchgear, 11kV & 22kV Switchgear, Auxiliary Transformers, Coupling Transformers, Transformer Rectifiers, 650V to 750V DC switchgear, RTU’s, HMI’s, Changeover Systems and much more.

London Underground Infastructure

London Underground projects

Typical projects on London Underground infrastructure include the manufacture, supply and commission of 46 No. LVAC Switchboards, for the Four Line Modernisation (4LM) Project. The Low Voltage switchgear is a product which is approved for use on the London Underground System.

Further projects have included the installation and commissioning into service of 11kV & 22kV Switchgear, DC Switchgear, Transformer Rectifiers and associated power cabling.

ISS are highly competent in the de-commissioning, disassembly and removal of redundant equipment on London Undergrounds infrastructure.

ISS deliver expertise in upgrading protection systems on the London Underground distribution network, replacing old electromechanical protection with modern protection devices, minimising outage durations. Upgrading the protection system prolongs the life span of distribution equipment substantially, increase performance and reduce maintenance cost.

Protection upgrades

ISS have upgraded countless 11kV & 22kV Feeder Protection Circuits. We have a long history of providing new Line Differential Protection and Backup Protection upgrades on the infrastructure completed, replacing old electro-mechanical relays such as the MBCI Translay schemes, with new Micom P521’s, RED 615, P121/2/7’s and Agile P14 relays. ISS provide the design, manufacture, installation and commissioning of protection panels.

Providing Resources into the Underground Infrastructure

ISS provide a range of highly experienced and London Underground certified resources to support London Underground projects, including;



  • HV1 Engineers (Isolate & Earth to 22kV).

  • HV2 Permit Acceptors.

  • LV1 Engineers (Isolate up to 1000V).

  • Project Managers.

  • LV1 Commissioning Managers.

  • Site Persons In Charge (SPC).

  • Substation Competent.

  • Substation Key holders.

  • Safety Critical Engineers.


HV1 and LV1 resources to support many contractors working on the Infrastructure, as well as providing these resources to support London Underground themselves. Allowing our HV1’s to isolate and earth 11kV & 22kV systems to progress your project, or LV1 Engineer to isolate and modify LV circuits. We provide highly experienced Project Managers and Commissioning Managers to complex projects on the London Underground network, providing these resources to London Underground and many contractors delivering projects on the infrastructure.