Magnetic fields from electric power lines: theory and comparison to measurements

It is shown that currents and magnetic fields should be described statistically, because load currents fluctuate considerably during the day. The source currents include both the current in all power line conductors and current which flows in the earth. The critical factor in predicting magnetic fields at ground level is the location and magnitude of the return current. Formulas for predicting the magnetic fields of power lines, given a knowledge of the currents in the power line conductors, are given. General characteristics of the magnetic fields near power lines are deduced both from theory and measurements