Calculating the Overcurrent Protection Circuit (OCPD) for a Water HeaterStep 1: Determine the Amperage (A) Drawn by Each Element

Amperage = Wattage / Voltage Element 1: 3000W / 240V = 12.5A Element 2: 6000W / 240V = 25AStep 2: Determine the Maximum Current (I) Drawn by the Water Heater Since the elements are connected in parallel, the maximum current drawn is the sum of the individual element currents. I = 12.5A + 25A = 37.5AStep 3: Determine the OCPD Rating The OCPD rating should be at least 125% of the maximum current drawn. OCPD Rating = 125% x I OCPD Rating = 125% x 37.5A = 46.88ANote

The OCPD rating should be rounded up to the nearest standard circuit breaker or fuse size, which is typically 50A.* Therefore, the correct OCPD rating for this water heater is

50A.

Conclusion

The overcurrent protection circuit (OCPD) for this water heater with a 3000W and a 6000W element on a 240V circuit should be rated for

50A. Flag for review