The Science behind the Cable - Boghead

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The Science behind the Cable

– and why you shouldn't worry!

Please note that this page only regurgitates information and guidance publicly available from the World Heath Organisation (with some added explanation for clarity). It is not the view of the Boghead Community Group (who have not, to date, considered or presented a formal view on this matter).

All electric items in our home or outside (wiring, electrical equipment, motors, etc) produce an Electromagnetic Field (EMF).

There are 2 components of an Electromagnetic Field - an electric field and a magnetic field. The electric field does not exist for underground cables (due to the shielding on the cable) but the magnetic field does. So that is the only part we need to consider. (Overhead electric cables produce quite different fields and studies related to those do not and should not be compared.)

The unit of measure for Magnetic Fields is the Tesla (just like Meter is the unit of measure for Distance). It is symbolised by T (just as Meter is m). The Tesla is quite a large value for measurement and so it is typically divided into millionths called a micro Tesla or µT for short.

The World Health Organisation (advised by other scientific bodies) has set the public exposure guideline for the general public for magnetic fields at 100 µT. This is based on a body of evidence over many years showing no adverse risk to people. Note that this is a guideline only as several everyday objects (and some key medical equipment e.g. MRI scanners) significantly exceed those guidelines (see below) and there are still no adverse effects.

Standing on a hillside with absolutely nothing around you would expose you to a magnetic field just from the earth itself of around 25 to 65 µT (depending on your location on the planet)

A typical 132kV single underground cable buried at 1m (as proposed through the village) if you sit directly on top gives a magnetic field of approximately 5 µT. At 3m that reduces to about 3 µT and at 15m is effectively 0.

But even standing on the road on top of the cable we are talking about a level only 5% of the WHO guideline. So absolutely nothing to be concerned about. And, in your home, behind the walls this is pretty much non-existent.

So let us put that level into context. If we compare the manetic field from the new cable to some other typical or household objects:
  • A car will typically produce a magnetic field of approx. 2 to 3 µT at head height (higher at foot level - up to 20 µT)
  • A hairdryer at 3cm from your head produces between 6 and 2000 µT (so that could be up to 20x the WHO guideline, or 400x the magnetic field at the road above the cable)
  • An electric razor produces between 15 and 1500 µT (up to 15x the WHO guideline, or 300x the magnetic field at the road above the cable)
  • A vacuum cleaner at 1m distance produces about 2µT (or 20 µT at a 30cm distance)
  • A microwave oven produces up to 8µT at 30cm distance
  • If you take an electric train to get to work that would typically expose you to 50 µT (or 50% of the WHO guideline).          

So, we are constantly exposed to Electromagnetic Fields of varying strengths in our everyday lives. The cable proposed to run under the road, with only the very small magnetic field produced, which is much less than many already existing in our homes, is something that should not be of concern.

World Heath Organization:
"In the area of biological effects and medical applications of non-ionizing radiation approximately 25,000 articles have been published over the past 30 years. Despite the feeling of some people that more research needs to be done, scientific knowledge in this area is now more extensive than for most chemicals. Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields."

You can find some of the souce material from the WHO here.

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