An electric water heater rated at 1500 Watts on a 120 VAC circuit requires a minimum fuse size of:

To determine the minimum fuse size for a 1500 Watt electric water heater operating on a 120 VAC circuit, we can calculate the current using the formula:

Current (Amps) = Power (Watts) / Voltage (Volts).

Substituting the values, we have:

Current = 1500 Watts / 120 Volts = 12.5 Amps.

When selecting a fuse size, it is essential to consider not only the calculated current but also the requirement to avoid nuisance blowing of the fuse due to surges, such as those that may occur when the unit starts up. Electrical codes, such as those enforced by the American Boat and Yacht Council (ABYC), typically recommend using a fuse that is rated for 125% of the continuous load for circuits that may experience momentary surges.

Calculating 125% of 12.5 Amps gives us 15.625 Amps. Therefore, the next standard fuse size that corresponds with this value is 15 Amps. Choosing a fuse size of this rating ensures that it can handle continuous operation without tripping while still providing adequate overload protection.

This makes the choice of a 15 Amp fuse the appropriate option, as it aligns with the calculated current