Question

All fixed storage water heaters of 120 gallons or less are required to have a branch circuit over current device and conductor rating of not less than ___ percent of the nameplate rating of the water heater.

a. 100
b. 125
c. 140
d. 170

Answer 1

Fixed storage water heaters of 120 gallons or less are required to have a branch circuit overcurrent device and conductor rating of at least 125% of the heater's nameplate rating to prevent overloading.

Step-by-step explanation:

According to the requirements stated, all fixed storage water heaters of 120 gallons or less must have a branch circuit overcurrent device and conductor rating of not less than 125% of the nameplate rating of the water heater. This is based on the National Electrical Code (NEC) which often requires circuits be rated for at least 125% of the continuous load to ensure safety and prevent overloading of the circuit components.

For 120-V electrical systems, factors such as the power consumption of individual appliances, the circuit's amperage rating, and the continuous use threshold of 80% for safety, all contribute to whether an electrical circuit would trip its breaker. For instance, if the combined power consumption of all appliances including an immersion heater, lamps, and a space heater, exceeds the safe operating limit of the circuit (calculated as 80% of the breaker current capacity), the circuit breaker is likely to trip to prevent damage.