On this page
- What are the issues?
- How do we manage these issues?
- What are Subdivision Corridors?
- What are National Grid Yards?
- What else do I need to know about?
- Where can I get more information?
Land use and development near National Grid assets (including transmission lines, poles, towers and substations) must be managed carefully so it does not create unacceptable safety risks, block Transpower’s access for vital maintenance and upgrade work (including emergency repairs), or otherwise restrict the efficient and safe operation of the National Grid.
If you want to develop your property and there are National Grid assets directly overhead or nearby, it is important that you contact Transpower to discuss your plans.
General building and land use enquiries are typically managed by our Landowner Relations Advisors (LORA) and Landowner Liaison Officers (LOLO). You can find out who your local LOLO is on our contact page, or by calling 0508 LANDOWNER (0508 526 369637).
Enquiries about sensitive activities (such as residential housing), subdividing, or development that may require resource consent from council, are managed by Transpower’s Environment Policy and Planning Group (EPPG). These resource consent enquiries can be submitted through Transpower’s online Corridor Land Use Management Enquiry Portal – Pātai.
The portal was created by our Environment team in collaboration with software developers Nuwave. Pātai’s purpose is to streamline RMA-related enquiries by providing customer’s a central portal to submit their enquiries and reduce the administration involved in the current process, for all involved. The portal also helps direct non-RMA related enquiries through to the right team within Transpower.
Incompatible activities and land uses must be set back from National Grid assets to avoid compromising their ongoing operation, maintenance, upgrading and development, or the safety of those living, or working around them.
Electrical and physical hazards due to incompatible activities can result in faults or power outages which have flow on effects for the security of the network. These can be inconvenient and expensive not only to Transpower, but to consumers. The main issues are:
- Blocking off access to support structures;
- Earthworks undermining the integrity of National Grid support structures (towers, poles);
- Risks of electrical hazard;
- Noise and visual effects; and
- Inconvenience to landowners, neighbours and the public.
To address these issues, we use National Grid Yards, Subdivision Corridors and Substation Corridors to describe the areas around our transmission lines and substations where you need to take care and consider Transpower in your design. Your council might describe these areas in other ways such as 'buffer or transmission corridor setbacks', however they all refer to the same need to restrict incompatible activities or inappropriate development around National Grid assets.
This approach is consistent with the government issued National Policy Statement on Electricity Transmission 2008 (NPSET), a planning document under the Resource Management Act 1991 (RMA). The NPSET sets national policy direction requiring the appropriate development of land under and near National Grid assets. All plan documents (such as district plans and regional policy statements) must give effect to the objective and policies in the NPSET. Councils must also have regard to the NPSET, when considering resource consent applications. We discuss this further on another page.
The National Grid Subdivision Corridor is the area where Transpower needs to be involved in the design and layout of a subdivision (and its subsequent land use). It is the area up to 39 m either side of the centreline of a transmission line. This is the general extent of the area where the conductors (wires) are physically present - as the lines can swing out this far in high wind conditions. The size of the corridor differs depending on the voltage and type of support structure. In the Auckland Unitary Plan, the National Grid Subdivision Corridor has varying widths in depending on the maximum “blowout”, or swing, of the conductors (“wires”) on each individual line span (the distance between the support towers or poles).
What can I do in the National Grid Subdivision Corridor?
Subdivision is an opportunity to design new development in a manner that takes the lines into account – including ensuring allotments are of a size that can be safely developed. Many activities, including residential buildings can occur within the Subdivision Corridor, provided they are set back from the National Grid Yard.
Within the National Grid Subdivision Corridor is a narrower National Grid Yard. The National Grid Yard is the area beneath, and immediately next to, National Grid lines (including their support structures).
It is a 12m setback either side of the centreline of a National Grid line and 12m in any direction from the outer edge of a National Grid line structure. This is reduced to a 10m setback where the line is a single pole line, although the distances from the structures remain the same.
What can I do in the National Grid Yard?
Transpower seeks to keep the National Grid Yard (NGY) free of buildings and structures and to manage land use and activities that could pose a risk to your safety or to the safe and efficient operation of the National Grid. What can (and can’t) be established within the NGY depends on where your site is located. Existing activities within the NGY can continue as is.
In any location (urban or rural), Transpower will not support any new or extended sensitive activities within the NGY. In many situations it is possible to design around National Grid lines and land within the NGY can be utilised for other activities.
If you wish to establish a new building or structure, subdivide, or substantially change land uses within the National Grid Corridor or NGY, please get in contact with Transpower through our online Corridor Land Use Management Enquiry Portal - Pātai.
These are activities that are more likely to be affected by National Grid lines relative to other activities, and include residential dwellings, educational facilities and healthcare facilities. Local planning rules may define other sensitive activities.
Your Council’s District or City Plan may give effect to the NPSET by including specific rules about subdivision, land use and development near National Grid transmission lines and substations. You can read more about this on our National Grid: City & District plan rules page.
In addition to our National Grid Yard and Subdivision Corridors, there are also a number of important regulations that contain mandatory requirements and safe separation distances for development near existing National Grid lines.
Our Development Guide provides useful information on the issues relevant to developing near National Grid Lines. You can download the document either in its entirety or in relation to the sort of development you may be considering:
- The Development Guide - full document
- Chapter 2 - What are the issues?
- Chapter 3 - National Grid Yards and Subdivision Corridors
- Chapter 4 - Small-scale residential development
- Chapter 5 - Large-scale residential development
- Chapter 6 - Large-scale redevelopment (brownfield)
- Chapter 7 -Commercial and industrial development
- Chapter 8 - Open space and recreation
- Chapter 9 - Rural and forestry land use
- Chapter 10 - Planting near the National Grid
Examples of common Corridor Management challenges
This house was built under the lines in Auckland before the corridor rules came into effect. Now, this house would need to obtain non-complying resource consent as it is located within 12m of the HEP-ROS A centreline. Non complying resource consent is the most difficult type of resource consent to obtain and the council would identify Transpower as an affected party (i.e. we could lodge a submission on the developer's application).
This photo shows the mitigation measures that had to be put in place to ensure the house could be built safely. This type of development is undesirable from Transpower’s perspective because there are on-going risks to occupants (e.g. getting on the roof to retrieve a frisbee).
If not carried out carefully, earthworks can create instability and erosion that threatens a structure’s stability and can result in also clearance violations (not maintaining safe separation between people and live lines). Photos taken from Auckland and Whitby.
Industrial and commercial development can block access and create reverse sensitivity/nuisance effects (restrict business activities). In many areas of Auckland, new commercial and industrial development needs to obtain a non-complying resource consent to be established within 12m of Grid centrelines. In other areas, these developments are permitted mid-span (the middle point between two support towers), although the code that controls safe separation between activities and transmission lines – NZECP:34 must still be complied with, which certainly isn't the case in the last photo!). Talk to Transpower’s Environment Policy and Planning Group if you would like more info on where commercial and industrial development is and isn't restricted in Auckland.
Container load and unload facility in Auckland which experienced a major electrical flashover when a container was inadvertently lifted into a live 220 kV line. This caused a widespread power outage that affected the upper North Island including the refinery at Marsden Point.
HEN-HEP 3 crane incident, December 2017
There are significant risks with mobile plant working under and near transmission lines. Despite NZECP:34 requiring a minimum approach distance, (separation between people/machines and live lines), the responsibility of maintaining these safe separation distances comes down to operator awareness and safety procedures on the site, such as use of “spotters” to warn mobile plant operators that safe separation has been lost. Transpower works with our Service Delivery Managers, Land Owner Liaison Officers and others to review construction management plans that detail how the risks of mobile plant are to be managed. We are also working with other teams at Transpower, including Health & Safety, to increase industry knowledge and awareness.
Subdivisions, where larger properties are broken up into smaller blocks, can result in our established access being physically blocked. These photos show towers “locked in” behind fences after a subdivision in Timaru was approved without adequate consultation and consideration of Transpower’s access requirements.