Whether the reports of health hazards are true or not is almost irrelevant. Just the fact that many people are truly concerned about the potential health effects of living near a wind farm, or the electromagnetic radiation from high voltage electrical wires, is reason enough to try to avoid buying a property that is close to power lines. It's a simple law of economics: As demand for a product goes down, so does its price. When you have a certain number of people avoiding a certain property, for whatever reason, the price of that property will be negatively affected.