What is the need for UNITS when configuring Outputs?

Im confused about the selection of Units when configuring Outputs. I want to graph Total Watts and Total Amps so I created these 2 Outputs:


With these inputs

When I plot Total_Amp and TOTAL_W as Watts the traces overlap each other:

When I plot Total_Amp and TOTAL_W as Amps the traces overlap each other:

When I plot Total_Amp as AMPS and TOTAL_W as Watts the traces appear correctly:

So, what is the purpose of selecting units when configuring Outputs? Can I rename Total_Amps as TOTAL, then graph it as watts or amps?


The units specified for the output are the default units that are used when displaying the output in the real-time status display, or when you query the output and do not specify a units method. Graph+ does specify a units method corresponding to the units that you selected. Note that in your three examples, the traces are labelled with the units being displayed.

Thanks for the reply. I did not think about the status display. I usually use graphs, both ad-hoc and saved.
Is there a way to change the inputs in the real-time status display to default to Amps?

Something to keep in mind when viewing amps instead of watts: you have no voltage reference being applied. When it comes to 240v vs 120v devices, they could both be drawing 20A, but one has double the voltage and thus double the power. This isn’t obvious at first glance of an amps status display.

Personally I try to avoid that view unless I have a specific reason to view it.

It is really nice to view on recently installed systems just to check that you are <80% of a rated circuit on continuous loads :slight_smile:

Darkassassin07 & iotapl, good comments and tips both.
My main reason for the iotawatt is to monitor circuits during power failures when I’m running on a 5500watt portable generator. All circuits are 120v since I can’t run the HVAC compressor or the electric oven on the small generator. My goal was to balance each leg of the generator output.

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Have you considered using VA to assess capacity? Like Amps, it doesn’t discount reactive power, but like Watts, it factors in voltage. When your generator says 5,500 Watts, they pretty much mean at unity (1.0) power-factor where VA = Watts.

If you haven’t already, check out uploading the data to InfluxDB and then displaying in Grafana. I’m doing exactly what you are doing, and being able to set charts with thresholds is nice

Also, do you expect to have internet when running on generator? Because Graph+ references CloudFlare for CSS and fonts, so you’ll need to set it up to work locally ahead of time