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Isolation transformers are wonderful things when working with high voltage devices with the case open and power on, like when trying to find a blown capacitor in a television. Greatly reduces your chances of dying should you touch the hot side of things, as hot isn’t referenced to ground – only the neutral on the transformer.
If you don’t put both hands on the device, and there is no path through your heart from hot to neutral, chances are good that you live, although you could still get burned on a hand if it’s a path between hot and nuetral in your device.