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We provide two main ways to connect to our network at our existing substations: a high voltage ‘bay’ connection or a lower voltage connection through a ‘tertiary’. If your project size justifies it, we can also ‘T’ into our overhead lines and build a new substation to connect you into.
Who is a tertiary connection suitable for?
A tertiary connection is typically suitable for smaller projects looking to connect directly to National Grid’s network. It is called a tertiary as it uses the third winding on our existing high voltage transformers. There are a limited number of tertiaries available across the network; you can see our current availability in our Research Assistant.
National Grid build the infrastructure assets and typically build the connection assets, although these can be built by you through a user self-build agreement.
Please note: Compared to a bay connection, tertiary connections can have higher downtime. Please enquire through our Research Assistant for this or any other options and we will set up a pre-application discussion to explain all the options available to you.
Who is a bay connection suitable for?
A bay connection is for larger projects up to 1800MW per bay (at 400kV). It’s called a bay as we provide a portion of our substation for you to put your assets into and provide a busbar (normally both main and reserve) for you to ‘clamp’ onto. We provide the connection point and you then build a transformer and all the assets up to the busbars.
We have two types of equipment in general: AIS and GIS (Air/ Gas Insulated Switchgear). Please use the Research Assistant to find out which type exists at the substation you are interested in connecting to. A GIS bay differs to an AIS one as the circuit breaker and isolator are part of the bay, therefore there is a different ownership regime at these substations. Please enquire through the Research Assistant for this or any other options and we will setup a pre-application discussion to explain all the options available to you.
A 'T' connection offers another way of connecting to our network. Our overhead lines are temporarily diverted whilst modifications are made to enable this connection, and a new, dedicated substation is built. It is generally not feasible to offer this connection near to our existing substations or for smaller projects, due to cost and planning reasons.
Due to the significant costs associated with connecting such projects, there are a couple of key considerations for you to think about:
Please enquire through our Research Assistant for this or any other options and we will setup a pre-application discussion to explain all the options available to you.