Daily challenge · 6 questions · ~3 min
Electrical Voltages Practice Quiz
Six questions on 120V, 208V, 240V, 277V and 480V — the voltages every apprentice meets in their first year. Each one drills the residential-vs-commercial logic and the √3 wye maths. Need a refresher first? Read the full guide: 120V vs 208V vs 240V vs 277V vs 480V explained.
Q1.On a US 120/208V three-phase wye service, what is the line-to-line voltage between any two hots?
Q2.Which voltage is used almost exclusively for commercial lighting in mid-rise North American buildings?
Q3.Why is US residential 240V described as 'split-phase' and not three-phase?
Q4.A 5 kW load runs at 240V single-phase. Roughly what current does it draw?
Q5.You install a packaged HVAC unit marked '240V only' on a US strip-mall supply. What happens?
Q6.On a 277/480V wye, you measure 277V from A-phase to neutral. What do you measure between A and B phases?