I am building a small brewery and would like to heat a barrel of aprox. 280 liters of water with an three phase heating element. Its power would be 15 kW. That means that connected to 400V the full curent draw would be 37.5 A and current on each phase would be 12.5 A. Our house has main fuses 3x25A so i assume that wouldnt be a problem. I have asked a former coworker if there are any limitations and he said that current draw on start is around 5x higher than current while normal running. That means that current on startup would fry the main fuses.
So i have two questions
Would i require to install a variable frequency drive for a soft start of the heating element.
Which way is best for turning the heating element on or off apart from manually disconnecting the plug from the wall socket. I am thinking of a three phase relay controlled with a microcontroller such as Arduino.