"John" wrote in message
oups.com...

Simon wrote:
I'm thinking of something like a clamp-on ferrite core around one of the
incoming cables close to the meter,

I can't find much evidence that anyone else has done it, nor can I find
any
consumer units with this feature built in.

Something like this?

http://cgi.ebay.co.uk/ws/eBayISAPI.d...m=290011770617
"sensors clip directly onto your existing electricity meter's cabling"

John


Thanks, that gives me some ideas.
The manufacturers have a website at http://www.electrisave.co.uk/
I've just found a DIY example at http://www.edcheung.com/automa/power.htm
but it sounds like he only gets 1mV output per amp of current into the house
from his clamp-on cores, so the job would not be entirely trivial.
If my electricity company meter was inside, I would try pointing a cheap
webcam at it and writing a bit of image processing software to extract power
figures - it's surprising how effective this approach can be.