I am trying to make a software to calculate electric field near transmission lines. When I checked it I got one awkward looking result. At any point near the Transmission line, I guess the time average (or net) Electric Field should be 0. Why should it have any preference on a value and hence on a direction because the Voltages are constantly changing from +ve and -ve. I guess we can tell this from basic principle of symmetry. But presence of 3 lines and their images (below the ground), makes all these confusion to me. Since my software returned result counter to my intuition, I am seeking some help here. Thanks.