I'm not sure running a lawnmower over slabs (which sit on enough concrete and foundation to easily bear the weight of a car) would have much effect on the line, which pops out of the gtound (and the concrete) right next to the house. The problem was with the line which led from there, across the front of the house (pinned to the wall, about six inches above the ground), then in through a hole into the lounge (living room). Some of the insulation on that line had perished and was letting water in when the wind blew hard and it was raining (which has been the case for the last few weeks).