What's the expected accuracy of (for example) the 50A clamp?

Reason I ask: I finally got my cabinet rewiring done, so I can measure total consumption. I was already monitoring 2 suspect sub-circuits, and now I would assume that sub1+sub2 <= total - however, that's not always the case. currently sub1+sub2 = 406W and total = 391W.

icarus75's picture

Hi petur,

Accuracy of the current clamp measurements is primarily determined by the power factor and variations in line voltage, see a.o. the [1] and [2] forum threads. My hunch is that sub1 and sub2 have a different power factor. Your total current equals the vector sum of the sub1 and sub2 currents (and not the scalar sum). Hence the total clamp will give a slightly lower reading than the sum of the readings of the two sub clamps.



petur's picture

Why didn't I think of that :/

One is computer equipment, which should have a pretty good power factor, the other is a fridge a suspect of gobbling too much power. I guess I can suspect it of having a bad power factor too....