Even metal dental work. And the old crystal radio kits when I was a boy. Cost almost nothing, came with no antenna but an alligator clip on a wire you'd attach to a metal fence or whatever. Not a big deal but some may not know...why do fluorescent lights give you buzz and hum? They are actually flashing 60 (in the US) times a second and each time throw some electrical interference into the air. Like a movie, we can't see it's flashing. Why does a dimmer do that too? Kind of the same thing, if it is set for 50% light then the light is off 50% of the time, flashing 60 times a second. Gee, two years of electrical engineering in college and that's about all I remember! I'm not sure about LED bulbs but I suspect they work that way too. Since analog (tungsten) bulbs are now illegal in many areas things are not looking good.