In load calculations, the unit used to express sign branch circuit loads is typically which?

In load calculations, the unit used to express sign branch circuit loads is typically which?

• A. Watts
• B. Amperes
• C. VA
• D. Kilowatts

Answer: (C)

The main idea is that branch-circuit loads are expressed in VA because VA represents apparent power, which accounts for both the voltage and the current actually drawn, including any reactive (inductive or capacitive) effects. In load calculations you’re sizing conductors and overcurrent protection based on how much current the circuit must carry. Real power in watts alone can mislead you when a load has a power factor less than one (like motors or ballasts); the current can be higher than what watts would suggest. If you know the voltage, you can convert VA to current with I = S/V for single-phase (or I = S/(√3 V) for three-phase). For example, a 900 VA load at 120 V draws 7.5 A, which directly informs conductor sizing and protection. If you used only watts, you might underestimate the actual current needed for many loads, leading to undersized wiring. Using VA ensures the calculations reflect the true electrical demand on the circuit.

The main idea is that branch-circuit loads are expressed in VA because VA represents apparent power, which accounts for both the voltage and the current actually drawn, including any reactive (inductive or capacitive) effects. In load calculations you’re sizing conductors and overcurrent protection based on how much current the circuit must carry. Real power in watts alone can mislead you when a load has a power factor less than one (like motors or ballasts); the current can be higher than what watts would suggest.

If you know the voltage, you can convert VA to current with I = S/V for single-phase (or I = S/(√3 V) for three-phase). For example, a 900 VA load at 120 V draws 7.5 A, which directly informs conductor sizing and protection. If you used only watts, you might underestimate the actual current needed for many loads, leading to undersized wiring. Using VA ensures the calculations reflect the true electrical demand on the circuit.