You would use the 208 voltage which is a three phase voltage, the 120 volts is each leg to ground or star point. The formula for Amps = kw x 1000/1.73 x Volts x pf. Pf = power factor.
To convert from kilowatts (kW) to amps in a 3-phase system, we need to know the system voltage. Using the formula: Amps = (kW x 1000) / (√3 x Volts), where √3 is the square root of 3. Assuming a system voltage of 120/208V, the amperage would be approximately 135.1 amps.
The demand load for 3 ranges rated at 9KW each is 27KW (3 x 9KW) and the demand load for 3 ranges rated at 14KW each is 42KW (3 x 14KW). Therefore, the total demand load for all 6 ranges is 69KW (27KW + 42KW).