1) Most cooktop small appliances are 120 volts. How many volts is the cooker rated for 120 or 240 volts?

2) A 10.8kW appliance is a 240 volt supply. Applying Watts Law where P = I x E, solve for I (Current). I = P/E = 10,800 watts divided by 240 volts = 45 amps. Thus a 30 amp breaker will always trip since the circuit is overloaded.

I am a licensed electrician and it is a commercial cooker. It has to be an internal problem. The circuit is fine. I thought you may know about this particular cooker.

1) The branch circuit over current protection device is undersized. Do the math by applying Watts Law. P = I x E. Solve for I

I = P/E = 10,800 watts divided by 208 volts = 51 amps. No way will a 30 amp OCPD protect a 51 amp load. The breaker will trip every time, especially if a continuous 3 hour or more load.