On Sep 3, 2018, at 2:30 AM, Gary Stainburn <gary at ringways.co.uk> wrote: > > ...Pentium M processor...tiny fan...assumed power consumption would be low. You could well be right, but I’m a fan of taking measurements over guessing. :) If you were in the US, I’d recommend either of these from personal testing: https://amzn.to/2NMWXJq https://amzn.to/2oyz5Oz I wrote the review voted most helpful for the latter item. You might want to read it. A clamp meter + line splitter is more fiddly to use than a Kill-a-Watt, but you can use the clamp meter for many more things, so it’s a better overall value unless you simply will not be doing those other things. Neither of those will work for you due to US vs UK AC line connector differences, but these two items appear to be roughly equivalent: https://www.amazon.co.uk/dp/B01DSQ30FO/ https://www.amazon.co.uk/dp/B00H99EECU/ plus: https://www.amazon.co.uk/dp/B075D512KM/ I’ve found the same clamp meter that I reviewed above, differing only in OEM labeling. I’m not too happy with my guess for the best line splitter, for two reasons: First, I'm unfamiliar with your UK power plugs, so I don’t know if that’s actually a UK plug. Second, two of the reviews of that line splitter point out a design flaw that you might care about. I’d have passed it by if I could find something better on the Amazon.co.uk site, but that is the best I found, alas. You need a line splitter to do this test with a clamp meter, else you get a zero reading since the electromagnetic field from the neutral line cancels that of the hot line: you have to measure one or the other, separately. It doesn’t matter which one you measure: the current through both lines is the same, differing only in direction, which is what we mean when we call something an electrical “circuit”. Alternate plan: build a “broken circuit:” https://tangentsoft.com/elec/broken-circuit.html You can either make one for an inline current meter, as shown, or take the basic idea to DIY your own line splitter.