Types of connection

Identifying the type of service you require from New Zealand's National Grid will help us in informing our initial concept assessment to you.  If you want 24/7 'always on' type of service then that would steer your connection type to a solution with double-circuit connection and n-1 security in transformer and critical equipment. If you can withstand occasional service interruptions lower cost options may be viable connection solutions for you.  For more information on typical connection options, service levels and associated cost ranges, check out the connection option downloads at the bottom of the page.

Can my new connection tee into an existing transmission line?

Transpower will consider ‘Tee’ connections, however depending on location you may incur additional costs to ensure Transpower’s wider transmission system remains secure.  Tee connections often require upgrades to automated fault protection systems over the wider transmission system. This can also include a need for new fibre deployed between your site, the connection point and Transpower’s existing sites.  Together this can add significant cost for a tee connection option.  It may be cheaper overall to consider other options such as a new substation at the tee location or extending your transmission line to a nearby substation.

Tee connections may not be allowed in some grid locations if there is a significant impact to service reliability for existing load customers.  Transpower can undertake a reliability impact assessment as part your project’s investigation, to determine which  connection options can be offered at your location.

If you are considering a tee connection, we also recommend you request a system study including protection analysis early in the process.

What do I need to consider when it comes to automated fault protection?

Automated fault protection systems automatically disconnect parts of the power system following a fault to prevent damage to both Transpower’s assets and your assets. New protection systems and changes to existing protection systems can be complex, costly and specific to your technology, connection type and connection location.  We recommend you discuss protection requirements with us and commission protection studies early in the connection process.

What happens if I connect to a constrained part of the network?

The New Zealand power system is run on open access principles.  You can request to build and connect anywhere you want, but Transpower will always need to manage the integrity and security of the transmission system.  You cannot buy or reserve capacity on the transmission system.

You can find more information on constraints in our Transmission Planning Report.  To understand the uncertainties at play when considering investing, refer to the Uncertainty and investment planning section (TPR 2021, Section 3.3).

I am thinking of connecting to an existing substation. Can I reserve a spare connection slot?

No, there is no mechanism to reserve spare circuit breaker panels or other spare capacity. Under New Zealand’s regulated market Transpower must commit spare capacity on a first come first served basis.

Spare capacity is committed when we have a signed Transpower Works Agreement for detailed design and build of your connection.

More information

Typical new generation connection options and cost ranges [ pdf 130.14 KB ]

Typical new load connection options and cost ranges [ pdf 122.54 KB ]

Typical connection options - reference diagrams [ pdf 559.76 KB ]