If you are procuring HV cable jointing or substation services for a new development connection, you will almost certainly be working within a framework that involves an ICP, an IDNO and a DNO — and possibly all three. Understanding what each of these organisations does and how they relate to each other helps you understand why the connection process works the way it does, and what R&D Cable Jointing's role is within it.
What Is a DNO?
A Distribution Network Operator (DNO) is a company licensed to own and operate the electricity distribution network — the cables, substations and switchgear that carry electricity from the high-voltage transmission system down to homes and businesses. The UK has six DNO licence areas, each covering a defined geographic territory:
- UK Power Networks (UKPN) — London, South East England and East of England. The DNO for most of our operating area including Kent, Essex, London, Hertfordshire and Surrey.
- Scottish and Southern Electricity Networks (SSEN) — South of England and North of Scotland
- National Grid Electricity Distribution (NGED) — Midlands, South West England and Wales
- Northern Powergrid — Yorkshire, North East England
- Electricity North West (ENW) — North West England
- SP Energy Networks (SPEN) — Central and South Scotland, Merseyside and North Wales
The DNO owns and maintains the existing distribution network. When new connections are required — for housing developments, commercial sites, EV charging infrastructure or renewable energy — the DNO is the network operator that the new connection will ultimately interface with, or that the connection will be made on behalf of.
DNOs carry out some new connection works directly, but a large proportion of new connection activity is carried out by ICPs working to DNO standards under the contestable works regime.
What Is an ICP?
An Independent Connection Provider (ICP) is a company accredited to design and install new electricity connections to the distribution network — working to the same standards as the DNO but operating commercially on a competitive basis. The ICP installs all of the new infrastructure — cables, substation, switchgear, metering — to the DNO's specification and hands it over to an IDNO (or occasionally the DNO itself) for ongoing ownership and maintenance.
The ICP model was introduced to bring competition to the connections market and reduce the monopoly pricing that historically characterised DNO connections. Developers can now approach an ICP to deliver their connection scope — often at lower cost and faster programme than going direct to the DNO.
ICPs are accredited under the NERS (National Electricity Registration Scheme) and must demonstrate compliance with DNO standards across their design, installation and testing activities. R&D Cable Jointing works regularly within ICP supply chains — providing the specialist HV jointing, substation installation and LV works that ICPs require to complete their connection scopes.
What Is an IDNO?
An Independent Distribution Network Operator (IDNO) is a company licensed to own and operate electricity distribution networks that are not owned by a DNO. Where a development is served by an ICP connection, the new infrastructure — once installed and tested — is typically adopted by an IDNO, who becomes the responsible network operator for that infrastructure going forward.
The IDNO model allows private ownership of embedded distribution networks — the 11kV and LV infrastructure serving a housing estate, a business park or a commercial development. The IDNO charges the DNO for use of its network assets under a connection and use of system agreement, and is responsible for the ongoing maintenance and operation of the assets it owns.
Common UK IDNOs include ESP Utilities Group, Energy Assets Networks, UK Power Distribution, Eclipse Power Networks and Fulcrum Electricity Assets — many of whom are clients of R&D Cable Jointing.
How ICP, IDNO and DNO Interact on a Typical Development
On a typical housing development or commercial scheme with a contestable HV connection, the roles work as follows:
- The developer appoints an ICP to design and build the new connection
- The ICP designs the connection to the applicable DNO standard, installs the 11kV cable, substation and LV infrastructure, and carries out testing and commissioning
- The DNO reviews the ICP's design, witnesses testing and commissioning, and approves the connection before energisation on connection day
- The IDNO adopts the new infrastructure from the ICP and becomes the responsible network operator. On connection day, R&D Cable Jointing as the SAP takes control of the new LV network on behalf of the IDNO
- The DNO makes the physical connection between its existing network and the new infrastructure — typically at a ring main unit or cable joint at the point of connection
What R&D Cable Jointing Does Within This Framework
R&D Cable Jointing operates as a specialist subcontractor within the ICP supply chain — and sometimes directly for IDNOs and DNO supply chain contractors. Our role is to provide the physical installation works that require specialist HV jointing expertise:
- HV cable jointing — installing the 11kV cable joints and terminations that form the HV cable circuit from the point of connection to the new substation
- Substation fit-out — installing earthing, small power, CT wiring and LV STC panels inside the new substation to DNO/IDNO specification
- Testing support — sheath testing, pre-energisation inspection and support through DNO audit and adoption
- SAP attendance — on connection day, providing the SAP who takes control of the new LV network on behalf of the IDNO and manages the switching operations for energisation
- LV jointing — installing service connections, MSDB and lateral cables as part of the LV scope
Already have an ICP or working as an ICP? We work regularly with ICPs and IDNOs across our coverage area. Send us your scope and programme and we'll confirm availability — we understand the ICP connection process and can fit around your programme without the need for lengthy explanation.
DNO Safety Rules and Authorisations
Works on or adjacent to DNO distribution networks must be carried out under the applicable DNO's safety management system — typically the DNO's own Distribution Safety Rules (DSR). Each DNO has its own DSR framework, and engineers working on that network must hold the appropriate authorisations for that specific DNO.
We hold UKPN authorisations covering our primary operating area of London, South East England and East of England. For works on other DNO networks, we work with our approved partner network and ensure the appropriate authorisations are in place before attending site.