Got my IoTaWatt set up - Question and FYI

After two weeks of waiting (four days just to get from NY to MO!), finally have my IoTaWatt and got it set up. One question - I assume that a red value in the readings indicates that it’s negative? Even though I placed the CTs with the labels facing the source as directed, I guess I’ll have to flip that one around?

Also, just an FYI if you’re interested, I did the calibration on the VT that OEM sent (IdealPower DA-10-09) and to get it to match what my Kill-A-Watt said the line voltage was, I had to adjust the cal value down to 10.9. That seems to be about spot on with the Kill-A-Watt.

Also, since I have more channels for monitoring now, I’ll likely be adding more CTs over time - for monitoring 220/240V loads (Air conditioner, range, etc), will a single CT on the neutral yield accurate values, or do I need a CT on each line and combine them in the graphing?

What defines the ‘quality’ value? initially, it was showing 1%, right now it’s showing 3%.

So far, I’d say the IoTaWatt is really nice - the setup and calibration I’ve done has been cake (calibration of the EmonTX was a bit of a chore IMO). Hopefully, once any bugs are ironed out, it’ll be more reliable than my EmonTX has been in the last year. The sampling alone seems to be a huge improvement over the EMonTX. For anyone that just wants energy monitoring, IMO, it’ a better value than the EMonTX as you really only need it to monitor energy, wheras with an EmonTX, you need that, and an EmonPi (Or Raspberry Pi and RFM69Pi) - by the time all is said and done, the 433Mhz gear will end up costing more. Now if you want to monitor temps as well, that’s different. My OEM 433Mhz gear will be for temp and humidity monitoring only once I move over fully to the IoTaWatt Within the next few days).

It’s all relative. You could flip the AC power adapter around (we can do that, the Euros can’t). So if more are red than black, start there. Even though they appear red in the status display, they will post as positive unless you checked “allow negative power”.

I have two kill-a-watt and they both agree with my Fluke 175 meter. You cal is about 1.5% off the number I got testing one adapter on two factory IotaWatts. Not too bad.

No and maybe. Some 240 appliances don’t have a neutral, and on the ones that do, you would only be measuring the net difference between 120 loads they apply to the two legs.

Whether of not the appliance has a neutral (white) wire you can:

  • use two CTs on the black and red, then add the two together to get total power
  • pass the two hot leads through one CT in opposite directions. The CT will then show the correct total power.

If the appliance has no neutral you can:

  • use one CT on either the black or red and double the resulting power to get total power.

I think you are asking about the quality displayed in the graph application. That’s just an indication of how many samples were available for the time period you are plotting. I’m assuming you just set your IotaWatt up and have only a little data on the graph. As time marches on and you get more data, that number should grow to 100% indicating you have data for 100% of the time represented in the graph.

Thanks for the positive feedback. It’s nice to hear when you spend most of your time helping people with problems.