Final answer:
The maximum amperage rating for the individual over-current device on the primary side of a 600-volt, 20-amp transformer is approximately 33.33mA.
Step-by-step explanation:
The maximum amperage rating for the individual over-current device on the primary side of a 600-volt, 20-amp transformer can be determined based on the formula I = P/V, where I is the current in amperes, P is the power in watts, and V is the voltage in volts. Since the power is equal to the voltage multiplied by the current, we can rearrange the formula to solve for the maximum amperage rating: I = P/V = (20A) / (600V) = 0.0333A or approximately 33.33mA.