A microelectronic device includes a first conductor and a second conductor, separated by a lateral spacing. The first conductor has a low field contour facing the second conductor. The low field contour has offsets from a tangent line to the first conductor on the low field contour. Each of the offsets increases a separation of the high voltage conductor from the low voltage conductor. A first offset, located from an end of the high voltage conductor, at a first lateral distance of 25 percent of the minimum separation, is 19 percent to 28 percent of the minimum separation. A second offset, located at a second lateral distance of 50 percent of the minimum separation, is 9 percent to 14 percent of the minimum separation. A third offset, located at a third lateral distance of 75 percent of the minimum separation, is 4 percent to 6 percent of the minimum separation.