Our setup is that we have an Eon Smart meter, a GEO clamp as part of the Energyuse trial and a Energenie Mihome Clamp as part of another trial. I thought I would compare the readings using the resistive loads of a 2Kw kettle and a 3Kw Immersion Heater. In the following table I have normalised the figures to remove the base load of some 400 watts due to lighting & computers running during the test.
Smart Meter GEO Clamp Energiene Clamp
2000 1793 2257 Kettle
3000 2745 3564 Immersion
As the Smart meter can be assumed to be accurate it interesting that GEO clamps used in this trail give a lower reading while the other trail gives a higher reading