When designing line of electric power transport, it is necessary to dimension these installations according to the high magnetic fields.
This present paper gives a method to calculate and represent the magnetic field around a three-phase line; it proposes to bring to the owner of these works the elements to the problems raised by this constraint: determination of the magnetic fields intensities to know their calculation and their measurement.
Certain spirits also worried about a possible physiological action of the magnetic fields; to appreciate such a possibility, it should be retained that the amplitude of the fields produced by the works of transport energy, on the surface of the ground about (1 to 10 μTesla), i.e. of the same order of magnitude as the earth’s magnetic field.
We present a calculation programme based on the MATLAB logiciel which makes it possible to better analyze and to represent the transverse profile of the magnetic field under the lines. We also give examples of application of the method and program.