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G59/G99 Applications

The current process for connecting generation units is set out in the Electricity Networks Association’s Engineering Recommendation G59-3 relating to Recommendations for the Connection of Generating Plant to the Distribution Systems of Licensed Distribution Network Operators.

New Engineering Recommendation G99 – ‘Requirements for the connection of generation equipment in parallel with public distribution networks’ is now in effect and generation connected after 26th April 2019 must comply with this document rather than EREC G59. For further information click here.

More information can be found on the ENA website at

We will make an assessment of the works required and associated costs following receipt of an application form. Once we have completed our assessment we will send you a quotation which will be valid for 90 days.

The works should normally be completed within 12 months of acceptance, although a longer timescale may be agreed for significantly larger developments. This is subject to change; for example, we may need to obtain permissions from third party landowners or the highways agency prior to commencing any works. We may also need to obtain specific legal rights and/or land ownership in relation to our assets being installed within your own land boundary.

Offer types

There are a number of ways in which we can assess your application and provide you with connection charges depending on your requirements:

  • Budget Estimate – we can provide a budget cost for providing an electrical connection to your development. These are not intended to be detailed studies of the network and will therefore only take account of the nearest point of connection. A budget estimate will not normally include any indication of reinforcement required upstream of your point of connection.
  • Connection Offer – we can provide a quotation for the works required, including upstream reinforcement or contributions towards works already completed under the Electricity (Connections Charges) Regulations.
  • Study & Offer – if you are unsure of the capacity you wish to connect, a Study & Offer quote allows you to assess the capacity options available without submitting multiple formal applications. Please note this applies to generation connections with export capacity of 5MVA and above only.
  • Alternative connections – On some of our networks, it is not possible to connect further generation without making changes to our assets. Alternative connections enable customers to connect where they are willing to have their connection curtailed under agreed conditions.

More information regarding each of these options is available using the links at the bottom of this page.


We will include within the Connection Offer a series of milestones that the customer must meet or risk losing their Offer. The milestones set prescribed periods that take effect from the acceptance date of the Connection Offer and indicate certain key stages in the scheme’s development that the customer must meet. The milestones provide a mechanism under which we can monitor the progress of a scheme and, if any milestone is missed (or likely to be missed) we can liaise with the customer and discuss progress with them.

For more information on the background to the introduction of milestones, the typical milestones and timescales included within a Connection Offer and how these are managed by WPD, please see our guidance on Extension of validity acceptance.

Witness testing

Engineering Recommendation G59 sets out the requirements for commissioning tests and checks. It is the responsibility of the installer to undertake these tests and ensure the generation units meet all the relevant requirements.

In some instances, we may need to witness the testing which will incur a fee. For further information regarding our fees please click here. We will notify you in advance should a witness test be required.

What happens next?

Once you are confident that you wish to proceed, please complete and submit an application form. The following flowchart identifies what will happen once we receive your application form.

How do I apply?

To make an application for connection, you may Apply Online, download an Application Form or contact your nearest applications team and ask us to send an application to you.

For applications to connection generating equipment which is less than 50kW three phase or 17kW single phase using Type Tested Generating Units, a simplified application form is available.

G59 Application Form
G59 Simplified Application Form

Lines are open Mon to Fri, 8:30 to 5pm

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Commissioning / decommissioning forms

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