What is the maximum allowable primary current of a 2 kVA step-down transformer with a four to one turns ratio if the primary is connected across a 440 volt line?

Correct Answer: Option A — 4.5 amps

Apparent power ($S$) in a transformer equals primary voltage ($V_p$) times primary current ($I_p$). For a 2 kVA (2000 VA) transformer on a 440V line, primary current is calculated as $2000 / 440 = 4.54$ amps. 46 CFR Subchapter J and IEEE 45 mandate accurate sizing for overcurrent protection device coordination.