Our response to coronavirus

Find out how we're working to keep the electricity and gas flowing reliably throughout the outbreak.

Guidance on your construction milestones – ‘Appendix J’

Your connection offer includes construction milestones (we refer to them as ‘Appendix J’) that both you and National Grid need to meet to deliver your connection.

We’ve collated the details around these milestones and included what information you need to provide to the ESO. Depending on your connection some of the milestones listed below may not be applicable.

If you use ConnectNow you can also update your progress against milestones within the portal.

1. Date by which connection offer should be signed
MilestoneDefinition

Date by which connection offer should be signed  

You need to sign the offer and return it to NGESO within the timescale specified. If you have any contract queries, please raise these as soon as possible so that we can address them. 

 

2. Apply for planning consent for your works
MilestoneDefinition

Apply for planning consent for your works 

  • You need to apply for the planning consents through the Nationally Significant Infrastructure Project or local planning

  • If you need planning permission for your development on NGET land, we need to approve the application before you submit it. The planning application boundary area should be minimised to avoid unnecessary National Grid land forming part of the application.

 

3. Get planning consent for your work
MilestoneDefinition

Get planning consent for your work

You need to get planning consent approvals or outcome from relevant authorities. The update should include the planning reference number and any specific information on the planning outcome.

4. Obtain land rights for your works
MilestoneDefinition

Obtain land rights for your works 

  • For any land outside of National Grid’s ownership for generation or connection assets, you’re required to obtain your own land rights. 

  • For any land within National Grid's ownership, please liaise with our Land and Property team [email protected] to obtain any lease or easement requirements within our ownership boundary. 

5. Sign the User Self Build agreement
MilestoneDefinition

Sign the User Self Build agreement   

6. Provide evidence of financial commitment / Final Investment Decision
MilestoneDefinition

Provide evidence of financial commitment / Final Investment Decision   

  • You are required to send email confirmation of the Financial Investment Decision (FID) to NGESO. This is a key milestone in the project as it used to support NGET's governance process to approve the project moving into the delivery phase. The FID is a final decision of your Capital Investment Decision process. 

  • You can demonstrate that a FID has been made by:
    - company with Board of Directors: providing a certified extract of your board meeting minutes confirming the FID has been made.
    - company without Board of Directors: providing confirmation that the FID has been taken by your Director(s). The evidence would typically be certified and provided in writing by your Company Secretary or by the relevant Director if you have no formal Company Secretary.

7. Confirm you have a contract or that you have procured long lead equipment for your work
MilestoneDefinition

Confirm you have a contract or that you have procured long lead equipment for your work 

You are required to share contract award confirmation with NGESO, high level information of assets ordered with delivery lead times (if applicable). You’re not expected to share any confidential information as part of the CONSAG.  

8. Work starts at your site
MilestoneDefinition

Work starts at your site

We require clear evidence of site establishment, e.g. site cabins and a spade in the ground. 

9. Confirm the design of your substation bays to NGET
MilestoneDefinition

Confirm the design of your substation bays to NGET

You are required to notify NGET for the design of the substation bays with relevant drawings. 

10. Confirm the agreement reached by you and the third party doing the third party works
MilestoneDefinition

Confirm the agreement reached by you and the third party doing the third party works

You need to share evidence of the agreement with the third party

11. Final diagrams are exchanged and agreed between you and NGET
MilestoneDefinition

Final diagrams are exchanged and agreed between you and NGET

You are required to share with NGESO and NGET a final single line diagram, asset layout drawings for any interface points and for any assets located inside National Grid's operational boundary. Please provide CAD and PDF files. For example: where the connection point is within our substation you are required to share information on the cable route inside the operational boundary.

12. Provide data exchange as outlined in the Technical Appendices (TOF)
MilestoneDefinition

Provide data exchange as outlined in the Technical Appendices (TOF):

  • SSR and Torsional Interaction Analysis 
  • Harmonic Performance Assessment 
  • Electromagnetic Transient Assessment 
  • Protection and Control Facilities 
  • Safety and Operational Interlocking Arrangement 

 

Where applicable, you need to share information on the items listed below. For access to the technical specifications from NGET’s extranet website, please contact [email protected]
 
SSR and Torsional Interaction Analysis 

SSR and SSTI (sub synchronous torsional interaction) is to study if the new connections (for example HVDC, windfarms or power electronics-based devices) could inversely impact existing generators or not. The studies check if they can oscillate (or initiate oscillation) with the existing generators or not.

Harmonic Performance Assessment 

This is how we make sure that the impact of a new connection on the levels of harmonic voltage distortion on the system are managed to within the limits set in EREC G5 as mandated by Grid Code. NGET performs a harmonic assessment and issues your harmonic specifications of harmonic limits that apply at the point of connection. These may be included in your offer. You then carry out a harmonic assessment and submit a compliance report to demonstrate the compliance against limits or mitigation options if the connection is not compliant.

Electromagnetic Transient Assessment

This is to minimise the probability and severity of electromagnetic voltage transients or transformer inrush at the grid entry point which may occur when your plant and apparatus is connected to or disconnected from the National Electricity Transmission System.  

You need to provide NGESO with details of such measures and an assessment of the predicted probability and severity of such transients or transformer inrush.  Following submission of this data further information may be required, see PC.A.6.2.1 or PC.A.6.5 of the Grid Code.  

Protection and Control Facilities 

To provide details of the Protection & Control facilities in line with the Appendix F requirements.  The equipment within NGET’s busbar protection or connections protection zone must meet the requirements of the Relevant Electrical Standards.  You must:

  • Complete and sign the Appendix F, Schedule 1 detailing protection at the NGET/User boundary.
  • Provide details of the Circuit Breaker Fail system for review and agreement by NGET.
  • Provide details of the CTs and other equipment which connects to and forms part of NGET’s busbar protection system.
  • Provide plant indications, GIS gas alarms and busbar protection/CBF alarms to NGET’s Substation Control System for the User bay.
  • Your backup protection settings must be submitted to NGET for review and acceptance.

Safety and Operational Interlocking Arrangement

This is required to ensure there is no paralleling of The National Electricity Transmission System through the Storage User’s System. Electrical and mechanical interlocking to be provided by the Storage User in accordance with Technical Specification: 3.01.01_RES.
 

13. You and NGET sign an Asset Transfer Agreement
MilestoneDefinition

You and NGET sign an Asset Transfer Agreement   

You need to sign the Asset Transfer Agreement issued by NGET.

The asset transfer agreement is applicable to bay connections where the ownership of the assets within an existing Bay (400/275/132kV) are transferred to you on acceptance of the agreement. 

The skeleton bay refers to basic civils structures, space allocated for further population of the Bay. Note that as part of the asset transfer any residual value of the skeleton bay, e.g. early asset write off will be charged back to you.

14. Submit all compliance documentation
MilestoneDefinition

Submit all compliance documentation  

You will need to demonstrate compliance against items identified in the compliance statement before energisation. This process can take a long time to complete and therefore it is best to engage early. The compliance process will be managed by a Compliance Manager from the ESO. For more information on the compliance process see:

https://www.nationalgrideso.com/document/95726/download

15. Confirm all necessary third party works are completed
MilestoneDefinition

Confirm all necessary third party works are completed  

You are required to provide a letter from the relevant third party to confirm that all works required have been completed and the third party accepts that the equipment will be commissioned for generation.

16. All of your relevant works are completed to facilitate Commissioning Programme
MilestoneDefinition

All of your relevant works are completed to facilitate Commissioning Programme   

Completion of all works required to facilitate the commissioning process.

17. Backstop date
MilestoneDefinition

Backstop date   

You must demonstrate that you will connect within the timeline given by the backstop date.