480 Volt 3 Phase Supply that is supplying a machine. I have measured the current in all 3 legs and need to calculate the power ( eg: the power that will spin the electrical meter). If it was balanced and all the currents were the same,, I could use "1.73 X v X I"

I have read that you can use the 2 watt meter method (Measure the current and voltage on 2 of the phases and calculate the Power, then add them and that will be the Kw).

I1 = 2.9 Amps

I2 = 5.2 Amps

I3 = 3.9 Amps

What would be the way to calculate the power?

Thanks!!