Sometimes only half power detected on 240v devices?

I noticed that sometimes sense only seems to correctly attribute half of the energy to my detected AC (presumably only 1 of the 2 phases on the 240v circuit?), with the other half being categorized under “other”. It gets it right 90% of the time, but I’m curious why it seems to be making this error.

Each phase/leg of your supply is monitored separately. The aggregated waveform that is displayed in the Power Meter is what you eyeball when you see, let’s say, that the “AC went on”. Sense’s “eyeballs” are on the phases separately. It has to make assessments regarding single-phase (120V) and dual-phase (208/240V) devices based on the “synchronicity” of those phases. Meanwhile other devices are introducing “noise” on each phase unevenly. Things can go wrong on one phase or the other that can throw things off.

An AC unit would be more prone to these mis-reads than a large resistive (208/240V) load like a hot water tank (4kW+) because the AC load is more noisy in itself so the “tracking” is harder. The load is also likely relatively of the overall load. The smaller the compressor, I suspect, the harder it is for Sense to track. I’ve seen very few errors in Sense’s native detection of my HW tank (208V - 4.2kW) but plenty of errors in my 120V, ~800W air conditioner tracking.


We discuss this in this video:


Thanks, that was very helpful.

Would love your thoughts on this other discussion: Electricity quality or noise score