Great responses! Thanks to all of you.
One of my (fire related) concerns was someone plugging in a device to my ethernet+power lines that wasn't expecting it. It looks that may not be a problem after all.
Daveg360 - thanks. I had heard of ethernet over power but not the converse. That looks very useful.
RuggedCircuits/bld - thank you for the links. I am digesting them this morning over a steaming mug of joe.