On Sun, 19 Aug 2018 12:19:58 +0100, alan_m wrote:

Clip-on power meters have been available for many years which do
this (albeit less accurately),

Mines pretty good once I got the tails passing through the clip well
placed.

I've had a clip on meter for many years. The novelty wore off after
around a week. The only time I now look at it is before leaving the
house for an extended time (holiday etc.) just to see that I haven't
accidentally left something on such as the immersion heater.

I capture the XML data stream mine produces and log it. Then have a
bit of PHP that'll plot a graph of consumption for a given day. I
look at that maybe a few times a week and normally catch her indoors
leaving the iron on or can see when she has...

--
Cheers
Dave.