What sensor for 3 phase over WiFi monitoring? IoTaWatt, Emporia Vue, Iammeter, emontx4, other options?

Hi there,

So I’ve taken up the task to set up electrical power consumption monitoring for the biggest consumers in our industrial sheet metal factory. Think of machines like air compressors, sheet metal punching machines, robots and co2 laser systems.

The goal is to create some dashboading of power consumption in homeassistant/grafana/influxdb so we can create awareness of power consumption (motivate departments to shut down machines in time) and get insights in standby-usage and maybe introduce some circuit breakers here and there to save some energy.

I am no electrician and mostly focused on the IT aspect of dashboarding and connectivity, so bear with me. Trying to find the best system here. (Installing the sensors will be done by a professional, not by me.)


  • CT clamping system, non-intrusive, we don’t want to put the power meters ‘in-between’ the grid transformer and the machines.
  • Ability to monitor machines rated up to more or less 200A on a 3 phase system.
  • WiFi connectivity to save significant costs on running new ethernet wires across our factory. We already have good wifi coverage. Protocol such as Zigbee won’t work, distances too large and imho not stable enough.
  • External antenna option (individual phase wires are often only accessible within sheet metal power cabinets (Rittal, etc.)
  • Open data portal, local connectivy option. For instance MQTT would be a big plus. I don’t want to rely on cloud services / subscriptions and want to be able to read the data streams and feed it into influxdb/etc.
  • Wishlist: Multiple 3-phase systems on a single ‘box’ would be a plus so we can also monitor from the power distribution cabinets instead of at the machines where the wires run to.
  • Not having to solder or flash custom firmwares and out of the box functionality would be a plus.

So here are the options I’ve found with pro’s and cons:

  • Iammeter
    Pros: Seems to match all requirements, can only monitor one 3 phase system per device
    Cons: Can’t find a lot of topics about or experience with this system here
  • IoTaWatt
    Cons: No external antenna support. Therefore probably won’t work within sheet metal power cabinets.
    Pros: Seems to match all other requirements, open architecture is a big plus, a lot of CT clamps per device.
  • Emporia Vue
    Cons: Requires flashing custom firmware and soldering
    Pros: From what I can tell seems to meet all other requirements, plus a lot of CT clamps per device.
  • Shelly 3 Pro EM and other Shelly products
    Cons: No external wifi antenna, only 3 phases per device
  • OpenEnergyMonitor emontx4
    Cons: Doesn’t support 3-phase in the current firmware yet, the model with wifi shield requires a server component to calculate values, docs say this system only monitors voltage on one phase so measurements might deviate a little bit (how is this for the other systems)
  • OWON PC321-TY
    Cons: Tuya based, no straight forward and/or reliable way to fetch the data over a WiFi interface. (There’s Zigbee2MQTT support for the Zigbee model, but I want to use Wifi, not Zigbee)

So far the Iammeter, as far as I can tell, is the only one which supports my requirements out of the box.

What do you guys think, am I missing or forgetting something? Know a better sensor I could use? What would be your suggestions?

Here’s a typical breaker box in a rittal cabinet, wires for this machine have a diameter of ~12mm:

We’re looking to do some very similar things in our industrial environment. So did you end up with Iammeter? How is this project progressing? Any tips you can share…

How about this?

1 Like

I have a supla mew-01 pending installation ( https://www.amazon.nl/3-fasen-wifi-energiemonitor-nieuwe-oplader-MEW-01/dp/B088PGSTXW/ref=asc_df_B088PGSTXW/?tag=nlshogostdsp-21&linkCode=df0&hvadid=452903905639&hvpos=&hvnetw=g&hvrand=12031707416371999231&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9064884&hvtargid=pla-1040839842144&psc=1 ) This one was easy to get running locally but is limited to 100A per phase and I’m not sure if it can support a delta hookup I stead of a star/y-scheme three phase machine.

For the 170A machinery in delta (no neutral line) I’m thinking about a modbus Schneider Electric sensor but I still have to figure out how to relay the measurements to HA / VictoriaMetrics. I’m somewhat reluctant to hookup our own Alibaba imported electronics to critical machinery. ( The delta scheme iammeter sensor also is only available on Alibaba )

(Supla is a polish EU brand with CE conformity.)

Please share what works for you too!

Here are more examples of iammeter selection and connection to home-assistant: Four ways to integrate the Electricity Usage Monitor (IAMMETER) into the home assistant