Measure electricity consumption for 3*230V delta grid

Hello community,

First of all, English is not my native language, so there might be some wrong translations (specially for electric terms).

I have 3*230V delta grid (3 wires and no neutral inside the main grid).There is 230V between each phase. I would like to know the consumption of my whole house.

I already have a shelly 3EM ( where I wired one of the phase as neutral.
In theory, according to the “two wattmeter method”, the power measured for the two other phases should be the total power of my house.
In practice, I have a 10% difference (too low) on month basis and up to 50% difference on low power (specially the night).

So this is my first question, is there any way to make the shelly work correctly for 3*320V delta ?

I also found an interesting device that is supposed to achieve what I want: iammeter WEM3080TD (note the D): Bidirectional Energy Monitoring System Din Rail Delta System Modbus Tcp/rtu Three Phase Wifi Energy Meter 150a,Wem3080td - Buy Energy Monitoring System,Wifi Electricity Meter,Solar System Monitors Product on As far as I know, this is the same device as WEM3080T but for 3*320V delta.

Does anybody know iammeter ? And moreover, does anybody have a WEM3080TD (and does it work :sweat_smile:) ?

Last question, do you have any other device recommendation working for 3*320V delta ?

Thanks for your help,


I have the same 3*230v without neutral feed from the grid. My understanding is that the 2 wattmeter method is OK for balanced loads. My house definitely is not balanced over the 3 phases.
I have just installed a Shelly Pro3EM with the 3 CTs, but do not yet have enough data to know if the total load is correctly measured.
The Shelly Pro3EM is designed to be used in a “Y” 3 phase net with neutral, but I succeeded in getting a “credible” measurement after reversing one of the CTs in this “delta” network.

I now need to compare the utility meter readings with the Shelly ones during some time.


I got an answer from Shelly support

Regrettably, the Shelly Pro 3EM requires a Neutral connection to function properly, resulting in inaccurate readings that you are currently experiencing.

Best Regards,

Shelly Support Team

That confirms my limited comparison of the measurements of the grid meter and the Shelly one.

Just saw this post. WEM3080TD is indeed Iammeter’s model specifically for delta. You can check it here Which type of electrical meter best fits your needs? ( Because it is rarely used, there is not much publicity. More detailed documents will be supplemented later.