Powerlines and EMFs

power lines gridOur electricity supply comes to us from a generating station, by means of powerlines. The majority of these are overhead cables, supported by large transmission towers or pylons. The cables emit magnetic and electric fields. Powerlines carrying smaller loads to meet local power needs are supported on smaller metal towers or wooden poles. Housing developments are often built near an existing line. Power cables can be routed above, or sometimes fixed to, houses.
The distance you need to be away from powerlines depends on how large the load is and whether the load is balanced. You also need to take into account the geography of the local area. Underground cables also emit high magnetic fields, which can extend outwards for a considerable distance. Due to the varied and often unpredictable paths that electric currents in our electricity systems use it is not possible to calculate the field levels in a typical situation. The only way of knowing your exposure is to actually measure the fields and compare them with the average magnetic field level of not more than about 0.05 microtesla for a UK home. There are other potential harmful effects from the electric fields, as revealed in research at Bristol University.
The Stakeholder Advisory Group on ELF EMFs (SAGE) was set up by the Department of Health to explore the implications and to make practical recommendations for a precautionary approach to power frequency electric and magnetic fields. It has now produced its first report, and more information is available from the Department of Healthwebsite.
This was followed by a "Cross-Party Inquiry into Childhood Leukaemia and Extremely Low Frequency Electric and Magnetic Fields (ELF / EMF)", which was set up to allow the five Members to consider in detail the evidence for an association between Electric and Magnetic Fields (EMF) from High Voltage Overhead Transmission Lines (HVOTL) and an increased risk of childhood leukaemia and determine what should be done. Their findings and recommendations can be found on the ePolitix.com website.
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Electricity Substations


Substations are part of the electricity supply network that enables the widespread use of electricity at home, work, places for education, leisure, commerce, health care, etc. The size of substations can be very variable, depending on whether they serve mainly residential properties, or also commercial and industrial units, etc. Schools and institutions such as hospitals often have their own substation.

Low power substations are found about 150-200 metres apart in a typical urban area. They are often grey metal boxes in a fenced enclosure. Sometimes they are inside brick or plastic structures. They have a 'Danger of Death' yellow sign attached to the fence. This is to warn the public of the danger of electric shocks. They change a high voltage coming into the substation, often 11,000 volts, though it can be higher, into 415/230 volts. Rural areas may have small grey box transformers attached part way up a wooden pole.


The bigger the substation, the higher the electromagnetic fields are likely to be and the further away a property has to be, to be in low fields. Measure the fields, it is easy and vital to do so.

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