Even if the area distribution lines are buried, the wires come up
to (usually pad-mounted above ground) transformers and the
BPL signal will permeate all the wiring in your (and your
neighbors') house(s) ...

Underground distribution will help (some) but it doesn't actually
solve the problem.

Right now, the emissions I heard in the trial areas were weaker in areas of
underground distribution. However, the losses are higher, so the utility would
have to install its digital repeaters more often along the underground lines.
It is a safe assumption that the industry that is asking the FCC for higher
emissions limits will increase the power so that underground wiring is at those
limits, too. We need to stay focused on what the rules would permit -- 30 uV/m
at 30 m -- rather than individual implementations that may be below the limits
in some cases.

Right now, the companies are probably using "stock" equipment for these
marketing trials. When it goes live, you can bet they will develop higher
powered systems as the most economical way to deploy in underground-wiring
areas.

73,
Ed Hare, W1RFI