Using an SCT-013 to calculate "low overhead" instantaneous power monitoring, is this method missing something?

[Bill.Thomson]

That will be OK if the frequency is tightly controlled where you are,…

The North American grid frequency drift is actually quite small.
Typically on the order of ±0.05 Hz.

DIY Current Monitor on Raspberry Pi. My power calculation isn't accurate. Help please?

It can, and does, but the actual amount is quite small. Viz: [image] As you can see, it dips and rises all day every day, usually anywhere from 59.95 to 60.05 about 98% of the time. If it ever drops below 59.9, or rises above 60.1, a serious system event has occurred, e.g. a major loss of generation or load somewhere in the US.