Wireless Electrical and Electromagnetic Pollution News
12 October 2011Earthing
In the context of earthing, I would like to add a few thoughts on the challenges people face who try to earth themselves in a wired world.
For body voltage testing, the testing protocol of the Building Biology Evaluation Guidelines SBM-2008 specifies that the person to be tested must be electrically isolated and that the person should not be close to grounded or earthed surfaces (e.g. earthing sheet).
SBM-2008 Explanations and Testing Conditions: http://www.baubiologie.de/downloads/manuskripte/randbedingungen2010.PDF (in German only, English translation coming soon)
The reasoning behind this is that body voltage testing shows a potential difference (never the electric field strength!), for example, between the potential of the human body and the potential of the earth. You do not have to be a rocket scientist to understand that when you "earth" the human body to be tested that it will have the potential of the earth, which is why in this case the body voltage reading, indicating a potential difference, will always be close to zero. No surprise here. This reading, however, does not tell you anything about the actual electric field exposure. Therefore, the VDB Guidelines ( http://www.baubiologie.net/verband/richtlinien/ in German only; VDB = German Association of Building Biology Professionals) state: "It is incorrect to use body voltage testing as the SOLE testing method with which to assess an exposure situation."
Proponents of earthing seem to be the only entities on earth that require a test subject to be "earthed" during body voltage testing. In this case, the body voltage testing does not tell you anything about the electric field exposures in the given space; it only tells you with its zero reading that the electrical connection between the naked human body and the earth is well established. Here is an article on the different ways of how electric fields can be measured and how, in a worst-case scenario, an earthing sheet can actually increase a person's AC electric field exposure.
http://www.buildingbiology.ca/pdf/ACHTUNG_ABSCHIRMDECKE.pdf
My recommendation: If you wish to earth yourself, be sure to choose a location where ambient AC electric fields are below 0.3-1 V/m, and as mentioned earlier, be also sure about a reasonably clean grounding connection.
Best regards,
Katharina
Katharina Gustavs
Building Biology Environmental Consultant IBN
Translator English/German STIBC
www.buildingbiology.ca
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