Smaller IoTaWatt Version


I have been lurking (and OEMC forums) here a few weeks while trying to assemble my own energy monitor. I have learned so much during my journey getting a single CT running and measuring, that I realize I don’t have the skills and time to really build a good system.

I really like the IoTaWatt because of the setup flexibility, the ability to work standalone and the multiple dB options. However, I am hesitant to buy because I know that I don’t really have use for a device with so many in puts and feel like I would be wasting money buying one. I know Emontx is out there, but it really doesn’t compare to IotaWatt, since the EmonTx needs a basestation which really doubles the price.

So my question is, (especially with the potential change to esp32 being investigated) is there any thoughts on a IoTaWatt lite?
Maybe something with the same software features, but half the CT inputs? Something in the 100$ unit range for a basic package.

Thanks for the project and all the information that is freely available! I have learned so much and gained a gigantic appreciation for all the engineering that goes into projects like this!

Hello @Judman13,

Sorry to say, it doesn’t work like that. Reducing the IoTaWatt to 6 inputs would only save about $5 in parts but increase the cost of ETL certification (they consider it a different listing). Moreover, fragmenting manufacturing into more runs of fewer units would increase manufacturing unit costs.

The bitter taste of low quality lingers long after the sweetness of low price.


I will also say that once you start, you will find that you will want more not fewer inputs. I started with a Brueltech ecm-1240. I really started down this path in the late 90’s when I worked on one of the first trials of demand-side load management with a utility in the Midwest. It was magical when on a Sunday morning, for the first time, I saw data from 4 houses and could tell a little about what was going on. Back then nobody had dreamed of something as affordable as the IoTaWatt.

Today I have two in my house and I feel I could use even more channels. Now that I am working from home, I can see how much power my workstation uses and I can see when it is not sleeping. If I only had one or two channels, it would be much, much, much harder to understand what is using power. There has been a lot of work put into disaggregation of loads, but I have not seen any results that are great. Having many channels is the path that works today. And as Bob said, the parts cost for the additional channels is not large, so not much savings there. The costs to have multiple products is very real and would need to be amortized across the number of units that would be sold. That would not yield a lower unit cost for a lite version. If there were going to be sales in the millions of units, it might make sense to offer a lite unit.


Same for me, I encounter more often that people need more like 20 inputs, definitely in case of a 3phase grid, 3phase solar and 3phase cooking equipment…

@overeasy, is it possible to measure 3phase consumption at once by putting the 3 cables all at once in 1 200A current clamp? Or is this ‘bad practice’?

When passing multiple conductors through a single CT, they must all be the same phase. So you can combine any number of three-phase loads into a single set of three CTs, but the three-phase ante is always three CTs.

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so it’s very bad practice :innocent: