Newbie here. Does this graph look okay?

Hi. I just set up Iotawatt and I’m new to all of this. Does the graph look okay? It’s monitoring the two (hot) mains coming into a 200amp panel. Also, I had someone tell me that the neutrals on a 240/double pole circuit need to be monitored in addition to the two hot conductors - is that accurate?


Yes, I think it looks realistic for what it is. You are graphing Watt-Hours (Wh) which is a unit of energy. Typically, I would look at Watts, a unit of power, for something like this. If you plot both Wh and Watts on the same graph, they will look identical, but the difference is that the units in the scale will be something that I can relate to.

For example, the larger increase around 22:00 is an increase of about 40 Wh. Your plot is showing 2 minute intervals, so that increase represents something that uses 40Wh in 2 minutes. That’s hard to understand.

(40 Wh / 2 min) x (60 min / h) = about 1,200 Watts. I understand 1,200W. That a fairly high power 120V load. We know it’s 120V because the other leg doesn’t change. The increase 2 hours before appears to be a 240V load as it shows on both legs.

So give Watts a try, it may be easier to understand. If you want to know the total Wh for that 24 Hour period, you can look at the statistics below the graph that will show the total Wh of a Watts plot line.

No, it is not accurate. In fact, some 120V circuits don’t have a neutral. Something like a well-pump or hot-water heater does not typically have a neutral. You can read about it in the documentation here.

Hi Overeasy, thanks for the detailed response. Is it accurate to say that watts is a snapshot in time, whereas wh is over a duration of time? For me watts–>watthours is analogous to mph–>miles driven (or perhaps, top speed in mph–>miles driven).

I see the yellow conductor is cycling at regular intervals. Does this mean necessarily that some amount of electricity is being used? Or would it look the same even if the panel didn’t have any branch circuits and there were no loads at all? If these topics are covered somewhere, please let me know as I’ll try to answer as many of my questions as I can.

By the way, I’ve really been impressed with Iotawatt so far. Everything about the experience has gone smoothly and I was particularly pleased that the setup went exactly as documented.


That’s a good analogy.

It does. Again, just add the Watts to that plot and you will see. The periodic yellow cycles are about 100Watts and I’d guess it’s your refrigerator.

If you had no loads, the mains would be flat zero.