Magnetic fields near overhead distribution lines-measurements and estimating technique

Measurements and analysis of magnetic fields in the vicinity of 51 separate overhead distribution lines are summarized. Data obtained covered a wide range of loads up to nearly 300 A. Results of measurements and correlation between the magnetic field and the phase currents at various distances from the line are discussed. A method of estimating the magnetic field exposure based on the load history of the distribution circuits is presented. A good correlation between the maximum primary current and the magnetic field at lateral distances within 15 m from the centerline was obtained. Near secondaries and service drops, magnetic fields generally decrease with increasing distances. A weak relationship between magnetic fields and conductor currents was found for secondaries and service drops.>