This paper presents calculations in the distribution of the electrical fields generated by the potential of phase conductors in overhead high-voltage power lines. The calculations relate to the area between the line paths and the terrain, with particular focus on the area near the ground, which is important in terms of any humans present there, temporarily or permanently. Field intensity distribution is determined for different arrangements of phase conductors and line paths, and for different tower designs. The optimisation criterion is the width of the area excluded from residential development, defined as double the distance from the axis of the line where the electrical field strength exceeds the regulatory permitted 1 kV/m value.