I use them in the house - but sometimes, when I am sitting in the barn for a long time (waiting on a kidding or whatever) I take the Powerline and plug it in, in the barn so I've got a wifi signal out there and can internet surf while I wait
My barn will be at least 50m from where the signal comes into the house, and the plug that 'puts the signal into the mains' but I don't think there's that much attenuation as the signal travels through the mains.