We used to use Isolating transformers, when we tested Armatures for shorted commutators and to sort the coil leads when we were rewinding them, Sure beat an RCD, you only got a shock if you touched both leads, can't say the same about an RCD. The thing I can't understand is that you were only allowed to use one appliance at a time with an isolation transformer, But a generator with floating windings acts the same as an isolation transformer, and it has no such restriction.
