Seven real diagnostic scenarios — nuisance tripping, voltage sag, motor overheating, ground fault hunting, harmonics, and intermittent connections — each worked from symptoms through measurement, diagnosis, and resolution.
"Replace the breaker and see if it holds" is a technician's move, not an engineer's. This module is built around the opposite discipline: measure first, form a hypothesis consistent with the measurement, then test that hypothesis with a targeted change. It draws directly on the components (Module 2), circuit theory (Module 3), power distribution (Module 7), and motor (Module 8) material earlier in this program — troubleshooting is that same knowledge applied under pressure, against a real fault someone is waiting on.
Every scenario below was chosen because it has at least two plausible causes that look identical from the outside — a tripped breaker that could be a real overload or a loose lug, a hot motor that could be a bad bearing or a lost phase — and each requires a specific measurement, not an assumption, to tell apart.