Dong wish to build a new windfarm in the North Sea and National Grid want it to connect to the substation at Mangreen; this requires Dong to construct an 80m wide cable corridor from near Cromer to the substation. In order to minimise transmission losses the cable should follow the shortest route. The cables will be buried 1.2m underground in 6 trenches about 8m apart (could be 0.7m where there are obstructions). Dong have been planning the route for several years and are proposing the route shown below through Little Melton - the purple area shows a possible alternate route.
The project has been given national infrastructure status as it will supply a significant part of the UK’s energy needs; this means that compulsory purchase can be used if necessary. Currently the project is still in the consultation stage, responses should be made by 20/09/17. A formal planning application will be made in spring 2018 and a decision will be made by the national Planning Inspectorate. Please see the Dong website at http://www.dongenergy.co.uk/uk-business-activities/wind-power/offshore-wind-farms-in-the-uk/hornsea-project-three-development for further information and how you can respond to the consultation.
The Parish Council is not directly responsible for any of the land affected by the cable and is not making a case for or against windfarms. The main purpose of this document is to highlight the possible consequences arising from the cable and to help parishioners reach an informed opinion by Sept 20th when the initial consultation period ends
The PC can only make statements that it can substantiate but recognizes that research into the environmental effects of power lines is still in its infancy and that some people have serious concerns about possible dangers to health. Therefore, the PC has also published on its website the views of some parishioners, which they have asked to be made public.
The PC chair will be available at the village show on Sat 9th between 14:00 and 16:00 and will do his best to explain the PC’s position on what is a very complex technical subject.
No buildings can ever be constructed over the cable. Some parishioners think that this is good as it prevents housing development.
The cables will raise the temperature of the soil above them, this can lead to drying out of the soil.
Electric cables create an Electric field in proportion to their voltage and a magnetic field in proportion to the current flowing through the cable. When you travel under the high voltage cables that pass over Little Melton Road and Burnthouse, you can often hear a crackling as the electric field acts on particles in the air. Because the Dong cable will be buried, Dong states that the electric field will be absorbed by the earth and not reach the surface. The magnetic field will extend about 10m either side of the outer cables in the corridor and because the cables are close to the ground surface, anyone standing directly over the cable will be in a stronger field than someone standing under an overhead cable.
Magnetic fields are measured in Teslas. One Tesla (T) = 1,000,000 micro Teslas (μT)
The field strength will depend on whether AC or DC is used to transmit the power and Dong will not decide on this until the project is granted approval, as wind farms are a new and evolving technology. AC fields induce a current in human tissue and this is an important difference from the static magnetic field generated by our planet. The maximum field strength directly over the cable could be be 55μT, the earth’s magnetic field is 50μT in the UK. Domestic appliances commonly generate similar strength fields and razors and hair dryers are much higher. Travelling on electric train can expose you to a 50μT field, an MRI scan can have a field up to 9,400,000μT. Dong state that Government has set a limit of 360μT for continuous public exposure.
Some studies have found a correlation between living close to overhead power cables and leukemia in children. Continuous exposure to an Electromagnetic field in the home is likely to be more significant than occasional exposure to the field generated by electrical appliances. As yet no biological mechanism has been found to explain how the cables could cause cancer and most of the mechanisms that have been suggested relate to the electric field from overhead cables but which Dong claim is absorbed by the earth above underground cables. The statistical basis of the studies has been questioned as confounding factors could be present.
The magnetic field from the cables falls off sharply with distance and will not be detectable beyond the edges of the cable corridor, so there should be no risk to people in their homes and on the public roads. The cables will cross under roads but the duration of exposure whilst travelling over the cable will be very short.
The cables will pass under the land owned by the Parochial Charity and by Crusaders rugby club (actually in Hethersett). People standing directly above the cables will experience a strong magnetic field. Whilst there is no evidence that this can be harmful, there are few comparable buried cables so there has not been time for long term epidemiological studies. If there is an effect on human physiology then it is likely to be at the quantum level and that is an emerging and complex science, so nothing can be ruled out. However, hairdressers and people travelling on electric trains regularly experience strong magnetic fields and there is no suggestion that their health suffers.
The PC does not believe that the cable poses a threat to the general population of the village and as users of electricity it is reasonable to accept some of the inconveniences associated with the supply. However because the technology and the related science are in their infancy the PC believes that a precautionary approach should be taken - especially as the cable will be in place for at least 25 years and will run under recreational land.