New install Question


I purchased and installed the IoTaWatt with 7 CT’s to start with. Install and setup was simple and all is working and pushing the data to my Influxdb for Grafana graphs that is awesome. Question is I have one branch with most everything on a smart UPS and the UPS says current load is 140 watts but IoTaWatt is reporting total 80 watts. UPS could be wrong or could something not be right with my install? That branch is very old wiring. Most of the house was upgraded. Thanks for allowing me in the group.


One or the other.

Another possibility is that your UPS is reporting apparent power while IoTaWatt is reporting real power. Apparent power is Amps x Volts. Real power, what you are billed for, is a little more complicated. The numbers you are quoting are a little outside of what I would call normal for this situation, but sometimes these first reports of discrepancies turn out to be a little different in controlled measurements. Usually, a UPS is connected to a computer and other electronics that tend to jump around a bit as the CPU, fans and disk do their thing. To rule this out, you would need to observe both at nearly exactly the same time, and also record the PF that IoTaWatt displays.

Incorrect installation might be one of two things:

  1. If you are a three-phase user, the phase assignment or orientation of the CT could cause this.
  2. The CT model may be incorrectly specified.

Another diagnostic test would be to plug your UPS through a Kill-a-Watt or other plug level power monitor. These things cost less than $20 and should be very close to the IoTaWatt’s reading. In my experience, they also have a pretty good voltage measurement, and so can be used to fine tune your voltage calibration.

Let me know how you make out.


Thanks, I’ll plug the kill-a-watt monitor in. I have one.


Thanks For our help. I was able to work on this again and turns out user error. I was mixed up on what input was what. This is a great tool and can already see how its going to pay for itself quickly just by seeing how much what is using.