Yes, it is. I had a device that I could plug into the wall outlet and any device plugged into that module could be controlled by the master control box. I could turn in on or off, and if it was a light, I could dim it. The devices had to be on the same circuit. I also had a device that turned your houses wiring system into one big antennae. Sounds good but you pick up all kinds of junk and it isn't as good as an idea as it seems. There was a box that was supposed to filter everything out, but it did not work very well.
Innteresting enough is what is gong on in the train part of this forum. N scale trains run on D.CC., each track being positive or negative. Now, they can send a digital pulse through the track and the train has circuity so that a train can be made to go backwards.. Theoretically, you could pull the Gomez Addams routine and make your trains collide which was impossible on N scale trains some years back. A houses wiring system can be used for all manner of things if the A/C is filtered or used to piggy back signals on.
As far as Radiation exposure from wireless LAN, HAHAHAHAHAHA!!! That's ridiculous.
(IMHO)