A single-phase lighting load operates at 277 volts, draws 20,000 watts and has unity power factor. For this calculation, apply a supplied 125-percent factor to its current. Which listed ampacity is the smallest that meets the resulting value?

Where to look it up

Explicit exercise assumptions; not a universal code requirement.

Why B is correct

At unity power factor, current is 20,000/277 = approximately 72.20 amperes. Applying the supplied factor gives 72.20 × 1.25 = approximately 90.25 amperes. Of the listed values, 100 amperes is the smallest that is not below 90.25. This compares the stated ampacities; it does not select a conductor or overcurrent device or establish a universal lighting-load rule.