Network capacity map and cost calculator terms and conditions

Network Capacity Map:

Cost Estimator:

The purpose of this tool is to help you to assess the availability of capacity on the transmission network in England and Wales. It gives a general indication of the capacity available for generation/demand developments looking to connect to the transmission system at major England and Wales substations. 

The colour gradings are intended to provide an indication to the user of constraints on the England and Wales transmission network and the areas where a connection is more likely to be achieved without the need for significant transmission reinforcement(s). 

The main points to note regarding the network capacity map are:  

  • the data is provided as an indication only and further system studies will need to be carried out in respect of the specific proposed connection during the connection application. This is to ensure we provide a more accurate measure of the impact on the transmission network in England and Wales 
  • the data within the map is updated every six months (to reflect changes on the England and Wales transmission network) but please note that the transmission system is always subject to changes 
  • the “generation headroom” and “fault level headroom” values given for the major England and Wales substations are calculated by taking into account connected generation, generation which has accepted an offer for connection but which has not yet connected and calculated capacity of the substation. These generation figures will regularly change as offers are issued, accepted or lapse 
  • the “demand headroom” values given for the major England and Wales substations are calculated by taking into account current peak demand values and calculated capacity of the substation 
  • currently the network capacity map cannot differentiate between multiple offers for the same transmission substation site inflating the overall connected generation figure and in the event this occurs the Interactivity Process outlined within the (Customer Use of System Code) CUSC will be followed. 

Please note that connections to the transmission substations with an overall RED classification are still possible, but there is likely to be a requirement for significant transmission network reinforcement.  

The network capacity map does not replace a full formal application when determining network capacity and to obtain a more accurate indication of the capacity available and any transmission works please submit an enquiry using the Enquiry Form.

The purpose of this tool is to provide you with an indicative capital cost of connection when considering a direct connection to the National Grid transmission network. 

It produces an indicative estimate of the cost of the connection asset works using costs incurred by National Grid in undertaking these types of works in the past. The specific transmission connection charges applicable will depend on the exact requirements of the connection and so the actual charges may differ from this estimate. If you want to discuss the specifics of your connection, please make an enquiry with us using the Enquiry Form.  

Things to note in respect of the estimate:

  • the cost estimator is generic and does not specifically consider the transmission network in terms of any additional transmission reinforcement works.  
  • It assumes there is no need to carry out any additional work. This will be determined at the point of application via technical studies  
  • it assumes that the transmission connection works are straightforward, the connection design meets the requirements of the National Electricity Transmission Security and Quality Supply Standard and that the cable is installed where no abnormal ground conditions exist (i.e. no public highway/river crossings) 
  • it assumes the route corridor for the cable circuit that extends beyond the existing substation is without obstructions/significant geological or topographical features 
  • it assumes that we will be carrying out the transmission connection asset works on your behalf. Please note that at the point of connection it is possible for you to undertake this work yourselves 
  • it assumes that your equipment will be compliant with the various industry standards and Grid Code requirements 
  • it assumes that land and space is available at an existing substation site and therefore the indicative cost is exclusive of any land purchase or consent requirements 
  • the costs of securities are not included within this tool and you may be liable for additional costs as part of your connection. 

The data within the cost estimator is updated annually so please note that the indicative cost is accurate for the present financial year alone. Based on the maturity of your requirements at this stage we have had to base our assumptions on our standard solution in accordance with the Customer Use System Code (CUSC) definition of Ownership Boundary. This may need adjustments to reflect the true position at the point of application. 

While we use reasonable endeavours to ensure that the cost estimator and related information is accurate, we do not warrant, and do not accept any responsibility or liability for the accuracy or completeness of the content or for any loss which may arise from reliance on the indicative cost or related information.  


The cost estimator and network capacity map give a general illustration of capacity and costs to apply to connect to the transmission network in England and wales. 

The network capacity map identifies where constraints exist. It is intended to give an indicative view and should not be relied upon to assess the network capacity or terms of a specific connection. While we use reasonable endeavours to ensure that the network capacity map and related information is accurate, we do not warrant, and do not accept any responsibility or liability for the accuracy or completeness of the content or for any loss which may arise from reliance on the network capacity map or related information.  

We have included maps showing the approximate boundaries of land owned by National Grid Electricity Transmission plc (“National Grid”) which may be of interest to you in the context of potential connections. Please note that the land may be subject to third-party interests or tenancy agreements. If the land is of interest to you and you would like to understand more about a specific plot, then please use the enquiry form on the Electricity Connections website.

Please note that in considering any enquiries National Grid is not making any commitment regarding the availability of the land or any associated connection which will be considered independently of each other or as a combined land & connection enquiry. Initial enquiries are limited to a maximum of 10 plots unless otherwise agreed with National Grid.

National Grid reserve the right to terminate the land option if contractual milestones and conditions are not met. Both National Grid and the customer can agree not to progress a Heads of Terms, if options are not progressed within 4 months.

This map does not currently include all the land owned by National Grid. It is our intention to include additional holdings over time and in the interim period we welcome enquiries around sites not listed.

Legal disclaimer: we have developed the guides to prices and timescales to assist you with connections applications. They give a general illustration of connections cost and time to connect only and cannot be relied upon to assess the terms of connections for specific premises. 

Subject to the above, we shall not be liable to you in tort (including negligence) or otherwise, arising under or in connection with your use of the cost estimator or network capacity map for: (a) loss of profits; (b) loss of sales or business; (c) loss of agreements or contracts; (d) loss of anticipated savings; (e) loss of or damage to goodwill; or (f) any indirect or consequential loss.