Journeyman Electrician Practice Exam

The rating of a branch circuit supplying a fixed electric water heater with a capacity of 120 gallons or less shall not be less than what percent of the full-load current?

1. 100 percent

2. 110 percent

3. 125 percent

4. 150 percent

The correct answer is: 125 percent

The correct choice for the rating of a branch circuit supplying a fixed electric water heater with a capacity of 120 gallons or less is based on established guidelines that ensure safety and adequate performance of electrical equipment. The National Electrical Code (NEC) requires that the branch circuit be rated at no less than 125 percent of the full-load current. This increase allows for the additional demand that might occur during operation, accounting for potential variations in current draw and preventing the circuit from being overloaded. Choosing a rating of 125 percent provides a buffer against surges or initial inrush currents which can be higher than the steady-state full-load current. This is particularly important for devices that may draw significantly more current when they start up, thus protecting the circuit and associated wiring from overheating and potential failure. The other percentages provided are inadequate for capturing these safety considerations. Thus, 125 percent is not only compliant with regulations but also ensures reliable and safe operation of the water heater.