121213-1028 EST
robbietan:
This is a useful reference
http://sp.ehs.cornell.edu/lab-resea...gnetic_Field_Safety_Program_Cryo_Guide_v4.pdf
On page 5 a limit of 5 milligauss for 60 Hz is mentioned.
If there really was 10 milligauss inside the house, then probably a good reason for the power company loss.
This morning I added filtering to my Gauss probe. Not much change in the readings from before. General noise level in the house is 0.5 milligauss (10 microvolts on the meter, 1/2000 of a Gauss) (the meter's quantizing and noise level), same within 4 ft of main electrical panel. At one input hot wire at the main panel top (meaning tight against the insulation on the wire) the reading was 2 Gauss today at the measurement moment.
Outdoors directly under my primary lines I am at this same 0.5 milligauss noise level. This was at whatever various orientations of the probe I picked.
I have a 3 phase primary with no neutral in my neighborhood. Any existing neutral is the earth and pipes in the earth. I assume a Y source at the substation to provide an earthing connection. I doubt there are any Y loads on my primary in my neighborhood.
Some time ago, more than a year, I put a big one turn wire loop, 10 ft x 30 ft, horizontally disposed, in my front yard below the primary lines and measured the induced voltage. This was in the low millivolt range, and fluctuated. Were the three primary wires in immediate contact with each other the ratio of their spacing to the 25' from wires to ground would have essentially caused there magnetic fields to cancel one another at the ground.
The court case you mention seems to imply a Y distribution system with a fairly large neutral current and a substantial portion of that neutral current in the earth path. Thus, a big source, big window in a one turn coil, from which the magnetic field was generated. Now distance from this one turn coil to the house interior is on the same order of magnitude as the window of the one turn coil.
I need to find a big high voltage primary, probably 345 kV, in the country and see what my Gauss probe reads. I generally know one place where DTE ties to Consumers Power, an isolated location. I know that there are ground currents at this point that don't flow in the direction of the power lines.
What I need, and some day I might cook up one, is a transmitted signal to give me zero crossing timing (phase information) from our power company so that I could determine what part of the ground current was correlated with the eastern interconnect (that is generally Canada (Ontario), NY, PA, OH, and MI).
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