What to expect end to end on your connections journey
We collaborate closely with the National Energy System Operator (NESO) to deliver your connection to the electricity transmission system. NESO will be the counterparty for your connections contract, with National Grid Electricity Transmission (NGET) contracting with NESO to deliver the associated works to connect you.
There are several key points to consider before you submit an application to connect to the high voltage electricity transmission system in England and Wales. These include, but are not limited to:
- Connection type
- Connection size
- Connection date
- Location
- Planning consents
It's also important to be aware of all the relevant codes all transmission system connected parties must follow. Visit these links below to understand more:
- Grid Code - The technical code that customers must comply with
- Connection and Use of System Code - The contractual framework for connecting to and using the National Electricity Transmission System (NETS)
- Security and Quality of Supply Standard - sets out the criteria and methodology for planning and operating the NETS
- Balancing and Settlement Code - Rules and governance arrangements for electricity balancing and settlement
Research Assistant update notice
As part of our ongoing commitment to providing accurate and relevant information, we have removed the Research Assistant tool from our site.
This decision reflects recent industry changes, including Connections Reform, and the evolving roles of NGET and NESO. We are currently reviewing and updating our digital tools to ensure they align with the latest developments and continue to meet the needs of our customers and stakeholders. This review will confirm whether the removal of the Research Assistant is temporary or permanent.
We appreciate your understanding and encourage you to check back soon for updated content. If there’s specific content you’d like us to include in future updates, we’d love to hear from you. Please contact us via our dedicated Contact Electricity Transmission page.
If you are considering applying to connect to the electricity transmission system, it’s important to understand how the reformed connections process now works.
Under the new arrangements, all new transmission connection applications are assessed by NESO. NESO reviews each application to check that the project is ready to progress and - for generation projects - that it aligns with government‑set regional clean power targets. This replaces the previous first‑come, first‑served approach and is designed to ensure that network capacity is optimised and allocated to projects that are both ready and needed.
Applications that meet the assessment criteria will be awarded Gate 2 status. These projects will receive a fully worked connection offer via NESO from the relevant Transmission Owner (for England and Wales, this is NGET).
Those applications that do not meet the assessment criteria are awarded Gate 1 status. These projects will receive an indicative, or ‘placeholder’, offer from NESO. Gate 1 projects can reapply in future once they are able to meet the requirements for a Gate 2 offer.
To find out more about the newly reformed connections process, visit the NESO website: Connections | National Energy System Operator
Once your application and Data Registration Code (DRC) are confirmed as technically competent, and your application fee has been paid to NESO, this triggers ‘clock start’.
Clock start marks the beginning of the three-month period to develop your grid connection offer, with NGET preparing the offer for NESO to issue to you.
Setting up your team
We will put together your NGET core scheme team, who will support you throughout the development of your connection. This team will be made up of:
- Relationship Manager: your consistent point of contact for all enquiries relating to NGET throughout the entirety of the connection journey.
- Power Systems Engineer: completes the power system analysis to determine the works that NGET needs to deliver to ensure compliance against the Security and Quality of Supply Standard (SQSS) and to facilitate a connection to the network.
- Connections Engineer: identifies the most appropriate connection product for your application and confirms the associated costs and programme for your offer.
- Revenue Analyst: analyses the costs associated with your connection and determines the appropriate charging elements for your offer.
- Contract Manager: collates all relevant information into a contract; ensuring that all agreements comply with our licence obligations, safeguarding both National Grid and our customers.
Analysing your connection requirements
Our Power Systems Engineers will run detailed computer-based power system analysis to assess the electrical impact of your project on the transmission network. The depth and scope of these studies depend on the data you provide. These studies are outlined below:
| Thermal studies: Determines power flow requirements | These studies calculate the current flowing through the power system, to ensure our assets have enough capacity to support your connection. All our assets have thermal ratings, so the study will show if an increased power flow due to the new connection remains within the safe rating of that asset. |
| Voltage studies: Determines requirements for any additional reactive compensation devices | Voltage studies may be undertaken to examine any potential voltage instability, voltage control coordination, or to calculate voltage step changes. This will allow us to understand if any new voltage compensation measures alongside your connection may be needed in case of any instability on the network. |
| Fault level studies: Determines required rating of circuit breakers | These studies determine the size of the circuit breakers needed in line with your connection, to preserve the safety of the equipment should a fault occur. To calculate fault currents correctly, we replicate worst case scenarios to ensure the system can handle all fault conditions. |
Designing your connection
Following the studies, we use the results to determine the most suitable design for your connection. This is guided by industry standards, such as the SQSS, ensuring the proposal is the most economic and efficient solution.
The Connections Engineer will develop this solution further by carrying out desktop exercises to calculate costs, define the design and outline the programme of work.
Drawing up your offer
Once the design is agreed, a NGET Contract Manager brings everything together into a contract. We then complete an internal governance process to approve the release of your offer to NESO. Following this, we prepare your Transmission Owner Connection Offer (TOCO) and issue it to NESO.
Final amendments
During the final 30 days, NESO may request amendments to the TOCO. We will work quickly to resolve these. Once everything is finalised, NESO will issue the offer to you.
Once you have signed your connection agreement with NESO, we begin shaping the technical and environmental foundations of your project, laying the groundwork for successful delivery.
We first assess how you will connect to the transmission network. Where existing substations have spare capacity, we may extend them to create a new connection point. NGET delivers all Transmission Owner (TO) works, while you are responsible for your own user (customer) works. Some connection assets can be delivered either by NGET or by you through a User Self Build agreement. These responsibilities are clearly set out in the connection agreement appendices.
If an existing substation cannot be extended, a new one may be required. We carry out site selection studies to identify the most economic and efficient location, considering technical, environmental and network factors. Land offered by customers is assessed alongside other options, and NGET leads on land rights, planning consent and community consultation.
We then progress the preferred design to a construction‑ready solution, coordinate delivery resources, and plan any required outages with NESO. Once you confirm your Final Investment Decision, we secure approvals, award contracts and move into construction.
Permitted Development Rights
You are responsible for securing the appropriate planning consents for your user works, including works which may take place on land owned by NGET.
Customers may not rely on NGET’s permitted development rights (which are reserved for the benefit of NGET’s transmission undertaking / NGET operational land) to undertake customer works, and should therefore ensure that they can demonstrate that appropriate consents are in place for all customer works, including on NGET land. Please refer to our guidance.
Regular progress checks will be undertaken to ensure both yourself and NGET are reaching key construction milestones for your project.
With the design complete and permissions secured, your connection moves into the delivery phase - where plans are brought to life. This stage focuses on the physical build and coordination of all technical elements required to deliver your connection safely and efficiently.
A dedicated Project Manager leads specialist teams to mobilise contractors, arrange site access, and order and schedule key equipment. During construction, further surveys and assessments may be carried out, and on‑site roles and responsibilities will be agreed with you. All infrastructure is built to National Grid standards, and commissioning preparation ensures every safety, technical, and quality requirement is met before energisation.
If you need access to our site to complete your works, this must be overseen by a Senior Authorised Person (SAP). As SAP availability is limited, access requests should be made as early as possible via your Project Manager.
For more information about the process for working near our substations, or on NGET’s owned or controlled land, visit:
Towards the end of construction and about 12 months before commissioning, you will enter the Operation Notification Compliance Process (ONCP). This process ensures all assets meet safety, technical and regulatory standards before energisation.
A Joint Commissioning Panel will manage key activities. These include system access - the planned outages of sections of the electricity transmission network to allow essential works such as maintenance, upgrades and commissioning of new connections.
The panel also oversees technical and safety checks, as well as settlement metering in line with the Balancing and Settlement Code.
Commissioning is the structured process that ensures your assets and NGET assets can operate safely and reliably together once installed and connected. It verifies that technical, contractual and safety requirements have been met before your site assets can energise and ultimately become operational. It runs in parallel with compliance activities and is supported by the Joint Commissioning Panel process.
Once commissioning is complete, your new assets will be ready to operate.
For further information, please refer to NESO's page on the compliance process.
Please note: If you are conducting a User Self Build project, the process will differ. Read more on User Self Build agreements.
When your asset has become operational, you will need to comply with operational Grid Code requirements.
These include coordinated outage planning for work on our transmission assets and providing regular technical data updates. The Transmission Network Control Centre (TNCC) will contact you in relation to outages required on the system.
Throughout the life of your connection, you will pay ongoing use of system costs to NESO, which covers the costs of maintaining the transmission network and day-to-day costs of balancing the energy system. You may also continue to pay for your connection assets, depending on the payment option you select.
During the life of your connection, you might plan to modify or re-plant your connection equipment. The size and nature of this may mean it requires a modification application, which you can submit to NESO through the NESO Connections Portal.
During this stage, our Engineering and Consultancy Solutions (ECS)* can assist you. Through this part of our business, we provide various additional services, including asset maintenance and refurbishment of customers' equipment, technical support, and consultancy.
*ECS operates independently of National Grid’s licensed transmission business. We encourage customers to explore all market options. Our services are offered competitively and transparently.
When you are ready to end your connections contract, you must give written notice to NESO declaring your intention to terminate.
Please ensure you discuss ending your contract with your Relationship Manager in both NGET and NESO. Once written notice is submitted, the process can begin. Our teams will then work with you to identify if any assets need to be disconnected, and whether you need to reduce your outputs or intakes in advance of your disconnection.
Once this work is finished, you will receive formal confirmation that your contract is terminated, a certificate of disconnection removing you from the balancing mechanism, and a reconciliation of outstanding costs.
