Master question of the day · 13 November 2026
Today's Master practice question
A 225-ampere feeder breaker supplies a panelboard of 60-ampere branch breakers, each with an instantaneous pickup of 600 A. A fault just past a branch breaker draws 2,000 A. The feeder breaker's instantaneous pickup can be set at 4, 6, 8, 10 or 12 times its rating. Ignoring tolerance bands, what is the lowest setting at which that fault will not trip the feeder breaker instantaneously?
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This question is original and written to Each state's electrical licensing board; exams delivered by PSI, Prov and other vendors's published content outline. A new question appears each day at midnight Eastern.