On 27/01/11 22:46, Kevanf1 wrote:
 Just to show my age :-)  I remember my complete scepticism when they
 were first put forward as a theory... back in about 1997 if I recall. 
The idea goes back a lot father than that Kevan. I remember a home 
automation system based around a Commodore 64 where the different 
components communicated over the mains. That would have been around 1986.
Google tells me it was also available for the Spectrum. Here's a page 
about it: 
http://www.worldofspectrum.org/hardware/feat34.html