Measuring consumption of a 400v 3 phase load

I’m getting started with energy tracking and for most of my loads it’s pretty straight-forward using a combination of Shelly plugs and PM1s. However, I have a sauna that I would like to also track the consumption of, and it is a 3phase 400v system. I have been unable to find equipment which can take that voltage. I was looking into the Shelly EM3, but while it would work in terms of amps, it is also rated 230v.

Does anyone know of hardware that can take a 400v load and measure its energy consumption?


Shelly em3 can monitor all 3 phases, its good for your use case. Its just being powered by one phase 230V, but can monitor the whole house consumption perfectly.

Iammeter should do it too Three Phase Energy Meter Wi-Fi,split phase,residential energy consumption,solar pv monitor,net energy metering, Modbus TCP/RTU I use these

Interesting! I actually asked Shelly but their response was that it was not possible since the device needs a neutral line from the load it tracks, and it does not support neutral from a 400v load.

Have you tried?

Ty! Looks interesting

That’s a bit confusing. Monitoring 3 phase systems is exactly what the 3EM is made for. Since it’s measuring currents through a clamp, I don’t see why it would need N from a load. There is no physical reason for that. Though it should measure the currents of a 3 phase 400 V symmetric load just fine. I guess it is a symmetric load, because otherwise there’d be an N.
Further: If the heater is really symmetric, without an N connection, you could also measure just one phase, both other phases have to have the same load.

Thanks for that!

Did you find a solution for your 3x400v consumption tracking ? I’m in the same situation and would like to know if Shelly 3em can do it.

There may be differents power grids around the world.
However, I can confirm that Shelly 3em will work with the typical European grid which is
3 phase 230/400V + N at 50 Hz

I contacted Shelly, and they told me that the 3em would NOT work with 400v. It will with 3 phase 230V, but not 400V. I did not try it myself but took their word for it.

I ended up using this one instead. It is rated specifically for 400v, and I can confirm it is working very well (incl local control via HA).

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I guess that was some kind of missunderstandig.

When you have 3 phases and N, you can get 230V and 400V at the same time and that will work with the 3em. If you have only the 3 phases without N, you have 400V only and that will not work.

EDIT: Again: thats for the european grid, somewhere else it might work differently.


L1 - L2 -> 400V
L2 - L3 -> 400V
L1 - L3 -> 400V
L1 - N  -> 230V
L2 - N  -> 230V
L3 - N  -> 230V