Frequently Asked Questions

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1. What is the purpose of these guidelines?

National Grid’s Sense of Place site layout and design guidelines provide advice and pragmatic solutions for anyone involved in the planning, design and development of sites and buildings near high voltage overhead power lines.

The purpose of the guidelines is to promote the highest possible quality in the design and development of such sites, while suggesting ways in which the visual impact of the transmission corridor can be reduced.

2. What’s the point? All sites like this will be undesirable and nothing short of moving the lines will make them any better.

In order to meet the demand for development land, society doesn’t have the option to reject all sites that are crossed by existing high voltage overhead lines, and nor should we. Many of these sites are in strategically important locations that can make a significant contribution to sustainable patterns of development.

The Sense of Place guidance starts from the position that good urban design is always beneficial. Poor urban design will lead to poor quality places, regardless of the presence of pylons and overhead lines, but good design can lead to positive place making and can improve the quality of places close to pylons and power lines.

If we can influence the design and layout of just a fraction of the sites affected by high voltage overhead lines, we will potentially have improved the quality of living and working environments for many people.

3. Where did the concept for this initiative come from?

For many years National Grid has published information for planning authorities and developers on the safety aspects, maintenance and amenity issues linked to developing sites near existing high voltage transmission lines and substations. For more information, visit Development near Lines.

We are aware, however, that there is increasing pressure on sites crossed by high voltage overhead lines to be developed, and that the urban design agenda is placing a new responsibility on all of us to promote the efficient and effective use of such land. That is why we believe these guidelines are particularly timely and relevant.

4. Are these guidelines a replacement for the existing ‘Development Near Lines’ publication?

No. The new guidelines go beyond the advice in ‘Development Near Lines’ to address more complex issues of urban design and the effective and efficient creation of positive public places.

5. How many sites are likely to be affected?

We estimate that there are in the region of 50 sites in England and Wales near or affected by National Grid’s high voltage electrical equipment that are currently earmarked for potential development.

Although National Grid has no control over new commercial or residential development near its existing lines, we always encourage planning authorities and developers to get in touch with us if they know a particular site like this might be going ahead. We can offer advice and information for the master planning for such sites.

6. Is this work relevant to all power lines or just the high voltage ones controlled by National Grid?

These guidelines relate primarily to existing 400kV and 275kV transmission lines – the transmission system operated by National Grid which connects the electricity generators’ power stations with the local networks of the electricity distribution companies. These are the pylons and lines that probably impact the most on the landscape and on public space, and that usually cannot be removed or re-routed.

However, the principles outlined in this guidance may be useful in considering any such constraint to development because of the way they illustrate good site layout and design solutions.

7. What examples are there of existing good practice that I could look at?

Our preliminary research around the country revealed very few examples of where a new site has been developed with any real consideration of the visual or physical impact of the existing high voltage overhead lines, pylons etc.

The appearance of the living environment in close proximity to transmission lines is often very poor, but our research has suggested that this need not be the case. A better example of how to deal with the transmission corridor is apparent at the Fairford Leys development in Aylesbury, where the lines have been accommodated in a riverine corridor (river plus overflow storage area). While it may not illustrate the only – or best – solution, it is noticeable that this development uses the land beneath the overhead lines to contribute in a positive way to the overall development to create a higher quality environment.

8. What other examples do you have of how this might work in practice?

We are currently seeking demonstration projects where we could work in partnership with the developer and local authority to test these concepts. In the meantime, we have developed a draft master plan for one particular site, at South Woodham Ferrers in Essex, which illustrates a whole range of solutions that we believe could allow the high quality development of the site and could offer interesting ideas for other sites too.

9. Can you supply the same master planning service to other sites?

Unfortunately not, although we are happy to talk through the various principles and techniques within the Sense of Place guidelines and to offer our advice and suggestions. The South Woodham Ferrers conceptual masterplan is really just for illustrative purposes, a way of demonstrating the practical application of the Sense of Place guidelines to a typical urban fringe potential development site.

10. Pylons and overhead lines are going to be visible however well the development around them is planned. Why not just re-route the high voltage overhead power lines, pylons etc, or put them underground?

Central Government, not National Grid or the local planning authority, approves transmission routes and these are chosen extremely carefully in order to minimise the environmental and visual impact of pylons and lines. There is rarely an ideal alternative. It is not sustainable continually to move infrastructure to accommodate development.

Underground cables are sometimes suggested as an alternative to replace existing high voltage overhead lines. We judge every case on its own merits. However, there are also severe disadvantages associated with high voltage underground cables and this is reflected in National Grid’s policy on undergrounding. To find out more about this issue, visit our undergrounding section.

11. What is National Grid’s policy on moving lines?

National Grid has had a policy in place for a number of years which seeks to retain existing assets in situ, recognising that there may be exceptional circumstances, such as developments of national or regional importance, where consideration ought to be given to moving lines.

This policy has been expressed to developers and local authorities in responses to enquiries to move/ underground lines, through Development Plan representations, and through National Grid’s publication ‘Development Near Lines – planning and amenity aspects of high voltage transmission lines and substations’. To find out more about this issue, visit our developers section.

12. What are National Grid’s objections to undergrounding or re-routeing of lines if the developer is prepared to meet all the costs?

As a general rule, any changes to National Grid’s assets that are in response to a developer’s request to move or underground an existing asset would be entirely at the developer’s cost. However cost is not the only issue in deciding whether it is appropriate to underground or re-route an existing overhead line route. Other environmental and technical issues also have to be taken into account.

We would prefer to see developers consulting with National Grid at an early stage in the planning process to find more innovative and sustainable solutions. We believe that by adopting a holistic approach in the early stages of site planning and design, developers and local authorities can overcome the constraints of developing land near high voltage overhead lines and can create positive, high quality environments.

13. How does this initiative address the health concerns about living near overhead power lines?

We acknowledge that there is a wider debate about the potential health effects of electric and magnetic fields (EMFs). EMFs are a natural consequence of most electrical apparatus, including power lines, underground cables and domestic appliances.

The current international scientific consensus is against there being a major public health risk from EMFs. This is backed up by current Government guidelines and the advice of the National Radiological Protection Board (NRPB). Consequently, we don’t support policies or proposals that rely on EMF and alleged health concerns as justification to control or direct development.

These guidelines are not intended to address this wider debate in any detail. Rather they promote the values of good urban design and primarily address the real and tangible issues of good planning and design. This means the guidelines will continue to be relevant whatever the outcome of wider debates. To find out more about EMFs and related issues, visit the EMFs website at www.emfs.info.

14. How does this advice help to minimise noise pollution from overhead lines?

Overhead lines do create some noise in certain circumstances, such as when minor surface damage, dirt or some weather conditions can cause the lines to crackle or hum slightly. However, if any noise is produced, National Grid makes sure that it is kept within strict statutory limits. The company retains its own noise measurement specialists to ensure compliance with statutory limits and to investigate any queries about noise raised by landowners, developers or members of the public.

What constitutes ‘acceptable’ noise levels is usually a highly subjective decision, and can vary depending on the other background noises, climate and the surrounding ground cover within the area. Consequently, our new guidelines can’t give overall advice on the proximity of buildings to transmission lines in order to reduce potential noise, but there may be other valuable and creative uses of the land, which mean that noise becomes less of an issue. For further information, visit our noise section.

15. What do these guidelines say about reducing the visual impact of pylon towers, lines etc?

The guidelines give a lot of detailed design and layout suggestions for tackling issues such as the linearity of transmission corridors, the orientation of streets, topography, development intensity, enclosure and built form, the orientation of blocks of houses or other buildings, screening and landscaping.

16. What are the risks of building too near to overhead lines?

Making contact or near contact with high voltage overhead lines is obviously very dangerous. Overhead electric conductors are normally bare (uninsulated) and if an object approaches too closely it is possible that a flashover will occur and an electrical current flow with the likelihood of fatal or severe shocks and burns to anyone nearby.

In order to prevent such incidents, there are clear statutory safety clearances prescribed and National Grid and the HSE provides additional detailed advice. (Advice on statutory safety clearances is contained in the Electricity Association’s Technical Specification 43-8 Issue 2: 1998 ‘Overhead Line Clearances’.)