Text size: A A A

3.12 Substations: associated with HV and EHV connections

You are responsible for:


  • Providing and installing lighting in the HV switch room to an intensity of illumination of 100 lux (In accordance with 'Recommendations for Lighting Building Interiors'). In general this will equate to a 1500mm fluorescent tube. For clarification, UK Power Networks will not provide and install lighting.

Earthing system

  • Installing their own earthing system. An earth terminal will not be provided with High voltage service terminations. You will also need to install a single earthing conductor between their installation and UK Power Networks' earthing system. This must come direct from the main earth bar (fitted with a removable link) and be clearly labelled. The sizing of the conductor will be your responsibility.

Emergency trip button 

  • Installing an emergency trip button, a 30v dc battery supply (complete with trickle charger) and multi-core cabling to UK Power Networks metering circuit breaker/relay panel. UK Power Networks recommends this, in order to comply with Regulation 12 of the Electricity at Work Regulations 1989.

Metering cable

  • The supply and installation of a 12core 2.5 mm² PVC/SWA/PVC cable, within appropriate ducting, from the meter position to UK Power Networks' Metering Unit to facilitate high voltage metering. The maximum length of metering must not exceed 20 metres.


  • The provision and installation of Your own Transformer and the associated cabling from the Metering Unit to the Transformer (N.B. cable to be made off by UK Power Networks at the Metering Unit).


  • Testing any earthing installation or cables installed by You and for providing a test certificate to UK Power Networks prior to connection to UK Power Networks’ system.

CTs, relay, TLF and fuse settings

  • Contacting the UK Power Networks Design Engineer to agree any CT specification and ratios and relay/TLF/fuse settings on Your equipment. This is essential in order to ensure adequate discrimination/co-ordination between Your equipment and UK Power Networks' metering circuit breaker.

Authorised persons 

  • Appointing Authorised Persons to take control and responsibility for the supply in order to avoid danger.
  • Providing the name and designation of the person who is to take charge of the supply and their preferred means of contact, so that procedures can be formally established for the safe operation or work on UK Power Networks' and the Your  high voltage equipment.

Site Responsibility Schedules (SRS) 

  • Completing the Site Responsibility Schedules (SRS) as requested by the UK Power Networks Project Designer or Project Manager. Please note this must be completed before the service can be commissioned.

Telephone line 

  • Installing a dedicated telephone line to the substation where a mobile telephone signal cannot be received within the substation.

LV supply 

  • Supplying an essential LV supply from your LV Network as required for remote control or battery charging purposes in accordance with EDS 08-0141