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Post Time: 25/06/2007 12:58:37 |
niccon
Total Forum Posts: 4 |
Hi there. Following the developement of many troubling health issues within my family since moving, I tested the EM field in our home with one of your meters and found it to be worryingly high in certain areas including bedrooms. Following your instructions, the tests showed that the source was the house electrical system.
I am now in the process of having the place rewired with screened cable in a bid to reduce these fields but noticed that our Earth supply was a bit outdated.
When I contacted my Electrical provider they suggested that they can either come and replace the existing supply system or they could install PME Earthing (if locally available) which is a newer type in which the earth is passed to ground via the Neutral inlet cable.
The problem is that screened cables absorb EM fields generated by the wires and feed them to earth. Would this PME earthing still be as efficient as a drain for the field currents given that it is connected via the neutral cable? |
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Post Time: 27/06/2007 10:39:13 |
alasdairP
Total Forum Posts: 173 |
Hi. The screened wiring should make a dramatic reduction in electric fields. The lighting circuits are usually the worst offenders re. producing high electric fields, by the way.
The earthing connection is not critical from the electric fields point of view and a good return to your Neutral is what is needed for protection against electric shock. I suspect that your existing Earth connection is adequate for this (though your electrician should check the Earth impedance using a suitable test method - there are special test meters avaialable, or you can dump current into the Earth and measure the voltage rise w.r.t. Neutral).
Given a 'clean slate', I would probably chose an proper Earthing rod into the ground - however, that also requires an Earth Leakage Circuit breaker which have gone out of favour with the IET who set the UK Wiring Regulations. So it is generally best to use the supplied Earth connection. PME is responsible for stray and net currents which can cause elevated magnetic fields over quite wide areas as Neutral currents can transfer the the ground and/or old metal gas and water pipes. However, PME is what most Electricity Network companies currently use. It doesn't matter from the electric field point of view. The electrical provider should provide a free Earth connection safety test for you.
So, to repeat, from the electric fields viewpoint, it doesn't matter how the earth is connected.
I hope this helps.
Alasdair Philips
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Post Time: 27/06/2007 20:46:23 |
niccon
Total Forum Posts: 4 |
Thank you very much for your replies and for your website! It will be good to finally see this problem sorted. |
