Master Electrician Practice Exam

What is the maximum load in VA that the branch-circuit conductors of a 20-ampere, 277-volt circuit are permitted to carry for continuous lighting?

1. 4000 VA

2. 4432 VA

3. 5000 VA

4. 5500 VA

The correct answer is: 4432 VA

The maximum load that branch-circuit conductors can carry for continuous lighting in a 20-ampere, 277-volt circuit is calculated based on the National Electrical Code (NEC) guidelines, which state that continuous loads should not exceed 80% of the circuit's maximum capacity. To find the allowable load for a 20-ampere circuit, you first calculate the total capacity by multiplying the current (20 A) by the voltage (277 V): \[ 20 \text{ A} \times 277 \text{ V} = 5540 \text{ VA} \] Since the lighting load is considered a continuous load, you apply the 80% rule: \[ 5540 \text{ VA} \times 0.80 = 4432 \text{ VA} \] Thus, the maximum load that the branch-circuit conductors can safely carry for continuous lighting is 4432 VA. This figure ensures that the circuit operates efficiently and reduces the risk of overheating or electrical failure over time. The other options do not adhere to the 80% rule, making them unsuitable for continuous loading scenarios.