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Case Studies

Calvert - HV Contestable & Private Distribution Supply


  • Client: WRG - WPD
  • Location: Buckinghamshire
  • Description: 11KV / 3.5Mva Contestable / Private Distribution Supply
  • Duration: 10 Weeks
  • Value: £376,000

Project involved the Design and Construction of a new combined 11kv Electrical Substation to accommodate DNO Contestable & Private11kv switch gear. An underground installation of 3kms of 11kv distribution cabling to a further new remote 11KV  sub – station to serve the main commercial building supplies onsite was also completed under the scheme.

Scheme was particularly challenging as this was a very busy existing private industrial site. Our works were restricted to a very tight project site, with traffic management and safety utmost. We were required to ensure that the ongoing business was not effected by our works, as customer commercial truck traffic was constant along where the route we were working through out the project as a whole.


Design of Contestable  - WPD  & Private 11Kv substation for incoming cable route, to include for electrical calculations for cabling and switch gear sizing, showing calculated losses, design earthing arrangement, protection arrangement.


  • Design & Construction of a new combined DNO & Private approved GRP Substation housing to include construction of concrete plinth. Installation & Construction was carried out on a very busy road so safety and planning were paramount with commercial truck traffic passing frequently due to existing business still functioning.
  • Contestable Installation & commissioning of 11kV underground cable between point of connection and customer intake substation including.
  • Contestable Supply and Install of WPD 11kV metering Ring Main Unit ,suitable protection relays, testplugs , NVD Protection panel plus voltage capping relay (Argus 8) , emergency trip button, Battery and Charger & Multicore cabling (cable to be provided and metering panel installed by DNO).
  • Below ground earthing arrangement installation around combined substation.
  • Private Supply and Install of 11kV switchgear in Combined substation and at remote sub 3kms away at industrial site compound
  • Grading study carried out between 11kv combined substation and remote new 3km site sub –station
  • Installation of Private 3kms of 11kv distribution cabling to serve a main commercial building onsite including all excavations, backfill and reinstatement.
  • Commissioning and testing to include for the provision of test reports, as laids & certificates.



Combined Installation of  11Kv / 3.5 Mva Contestable / Client  Distribution Supply

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