2.4 Transformers and the mains

I declare: solidlikelyshaky

1. Explain the turns ratio and verify it on a small transformer, unloaded and under load.
2. Draw the residential mains of New Brunswick: 120/240 V, the two legs, neutral, ground, and say what each does.
3. Explain why ground and neutral are bonded only at the panel, and what a neutral-line reversal does to an appliance.
4. Measure mains voltage at an outlet with the safe method, and identify line, neutral and ground.
5. Explain three-phase in three sentences (three sine waves 120° apart) and why big motors and e-bike inverters speak it.
6. Diagnosis: a transformer that heats up unloaded, saturation, shorted turns or wrong primary voltage; how to decide.