Posted by S Andreason on
URL: https://www.es-forum.com/EMF-Blocking-tp3349069p3355629.html

Hi,
C.a.b. Johnson wrote:
> piece in front of the refrigerator wide enough to block the magnetic radiation from bending around the back towards the front.  
Magnetic fields move in a circular pattern. Toroids actually. Not in a
straight line from the center.
So it is best to avoid calling it a radiation.

>   I could buy a new refrigerator for that but I suppose that the new ones are just as bad as the old ones.
>  
Not always, but in this case it is probably safer to say they all put
out an unwanted magnetic field, as they all have motors. Except the
amonia-based propane burning models for travel trailers and off grid use.


> So how to go about blocking the Refrigerator with Mu Metal?  Do you suggest just leaning a piece up against it and rotating it around to block whereever you might be?
>  

It is not that simple. One flat sheet, won't cut off very many of the
circular bands, unless the magnetic field is smaller than the mu-metal
sheet. The magnetic force comes AROUND the (fridge/motor/magnet) from
one pole to the other. For mu-metal to be effective, it needs to
encompass the magnetic field without creasing, or sharp bends. (It must
be kept smooth.)
Then the thickness of the mu-metal will also determine how much of the
field is attenuated. I get about 50% reduction with the 0.004" thick
foil I got wrapped around an AC motor, and in another little project I
made a half cylinder around a transformer. The literature says up to 75%
reduction with one layer.

I still find avoidance is easier.

Stewart