Shielding by a house from the electric field of a power line

The claim that "a typical house shields about 90% of electric fields from o utside" is examined when the house is located near a high-voltage 50- to 60 -Hz transmission line. Calculated electric fields near such a line are used . In order to provide an accurate analysis, the usual house shape is approx imated first by a hemisphere, then by a cylinder, and finally by a box-like shape on the conducting earth. It is shown that when actual materials and wall thicknesses are used, the electric field in the house is 99-100% of th e incident field, so that there is no shielding. The electric field scatter ed into the house by an iron plumbing vent that extends from the ground to above the roof is found to be significant near the pipe. Scattered fields f rom plumbing and heating pipes and electric wiring are significant only wit hin a meter or less. It is concluded that the superposition of incident and scattered fields from pipes and wires in the walls yields widely varying f ields at different points but that the average exposure of persons living i nside the house is not greatly reduced below exposure to the unmodified fie ld of the power line.