Electrician here, apparently it’s amateur hour with the voltage jokes, but I digress. The power lines should be relatively okay, the hum noise is from the electrical field being stronger than what is needed to push some electricity into the air around the lines. Humidity makes it easier for that to happen, but it isn’t super dangerous. There’s basically enough power flowing that it’s making it into the air. 10 feet seems way too close to any property line, but I would imagine that the power company and zoning board had to have talks about it? In the end, the hum should be lessened on drier days, don’t go near the lines with anything metallic, but if the look of them is that much of a downer, I suppose keep looking