Calculation of 3-phase power in Electric Vehicle Charging
The phase to phase voltage is 400V, which gives 230V phase to neutral voltage. \$\dfrac{400}{\sqrt3} = 230\$. 

So the formula is \$\dfrac{400}{\sqrt3}\cdot 3\cdot16 = \dfrac{\sqrt3}{\sqrt3\sqrt3}400 \cdot3\cdot16 =400 \sqrt3\cdot16\$. Or \$230 \cdot3\cdot16\$