On 13/05/18 11:16, Harry Bloomfield wrote:
Jim K was thinking very hard :
Well yes there is that, I was thinking of a decent clip-on device
to check my consumption & electricity bills...

You can get clip on ammeters, but they may not be that accurate and
with lots of things still drawing current, such as fridges cutting on
and off, the current demand will be very variable. An ammeter will also
take no account of voltage, but then nor would my method of a rough
check via a 1Kw load.

For a £36 cheapie on eBay
https://www.ebay.co.uk/itm/Voltcraft-VC-520-Clip-on-Ammeter-AC-/122327443586),
this is the quote from the technical data:

"Measurement tolerances
Statement of accuracy in ± (% of reading + display error in counts (=
number of
smallest points)). The accuracy is valid for one year at a temperature
of +23°C ±
5°C, and at a relative humidity of less than 75 %, non-condensing."

For an AC measurement on the 40A range, it is stated to be ±(3% + 12).
I can't quite get my head round that, but I would guess that at the
lower end of the scale, it becomes pretty inaccurate.

Or, for £27 and a basic accuracy of 2.5%, you can get a clip-on adapter
giving an output of of 10mV/A, which can plug into your digital multimeter:
https://www.conrad-electronic.co.uk/ce/en/product/122376/VC-510VOLTCRAFTClip-on-ammeter-adapter-0-400-AAC-30-mm?queryFromSuggest=true

--

Jeff