Reserving capacity (PARCA and CAM)

Before you apply, you will need to consider reserving capacity through the Planning and Advanced Reservation of Capacity Agreement (PARCA) process. A PARCA is a bilateral contract that allows entry and/or exit capacity to be reserved for the customer while they develop their own projects. The Capacity Allocation Mechanism (CAM) incremental process allows capacity to be allocated for interconnection points (IPs).


The PARCA allows you to reserve capacity, but it does not provide you with a connection to the National Transmission System (NTS). If you need a new connection to the NTS, or a modification to an existing NTS connection, you will need to go through the application to offer (A2O) process.  

The A2O process typically takes three years from application to the construction of the physical connection. As the capacity process (PARCA) and the connection (A2O) processes are separate, you have the flexibility to initiate these two processes at your discretion.

A diagram of how the PARCA process works

How a PARCA works

Initially, a customer will submit a PARCA application requesting the capacity they need. We will use the information provided in the PARCA application to determine how and when the capacity requested can be delivered.

An important aspect of the PARCA arrangement is that it helps the customer and National Grid to progress their own projects in parallel. It also assures the customer that capacity has been reserved with the option to buy it later. The financial commitment to the capacity (allocation of capacity) itself is required only once the customer and National Grid are relatively sure that their projects will go ahead.

The connection and capacity processes are separate, but they can become dependent on each other. To prevent stranded capacity, we won't allocate reserved capacity if a new or modified connection is required, unless a full connection offer (FCO) has been reached and accepted. Typically, it can take around 12 months to receive and sign an FCO, so the A2O process (if required) needs to be started at least 12 months before the capacity allocation date defined in the PARCA contract.

The timescales associated with the PARCA process may be up to seven years from application to the physical build of any capacity where required, depending on project timescales and our delivery of the capacity.   

PARCA guidance and documents

The following documents will provide you with a more in-depth understanding of the PARCA process, particularly the PARCA Customer Guide, and the application form needed to start the PARCA process.  

Also see:

Transmission Planning Code

PARCA notices

Current PARCA notices

Past PARCA notices 

Applying for a gas connection

To find out more about the application process for connecting to the NTS (A2O) please refer to our Applying for a Connection page.

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Capacity Allocation Mechanism (CAM)

In order to harmonise the development process for incremental capacity, new rules for incremental capacity have been included in the network code on Capacity Allocation Mechanism (CAM NC). An amended version was approved by the EU Member States in October 2016 and came into force on 6 April 2017.

The newly introduced process has several phases, including certain requirements that need to be fulfilled, before an incremental project can be initiated based on market demand and new capacity requirements.

CAM Incremental flowchart from National Grid plans
  • The market demand assessment will be conducted in accordance with Article 26 of the Official Regulation (EU) 2017/459 of the amended CAM code, hereafter referred to as the CAM Code, and covers how the market will signal to TSOs a potential need for capacity beyond the unsold technical capacity available.

  • The project design covers technical studies and a TSO-led public consultation on the proposed incremental project.

  • National Regulatory Authority (NRA) approval covers the finalisation of the project proposal followed by an NRA decision on whether the project goes ahead.

  • The allocation mechanism can be via the standard annual yearly auctions at interconnection points (IPs), or an alternative mechanism can be proposed under the project design.

  • National Grid intends to use the alternative mechanism to follow the existing Planning and Advanced Reservation of Capacity Agreement (PARCA) process as much as possible.

  • Any allocation or reservation of capacity will be subject to an economic test.

  • The CAM process does not cover rules for gaining planning consent or for construction, however, these remain a necessary part of the process for creating incremental capacity, and are considered as part of the process rules where appropriate.

For further information regarding the CAM Process please contact us by email.