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We use isolation transformers for many reasons, one of them is may be safety. So why not just keep the distribution transformers floating? If they're floating, then someone touches the live wire, I don't see how this would present a safety hazard.

The closest earthing system to this configuration is "IT". But I don't want to keep the impedance in the leaking current path, we'll keep it as high as possible, floating.

Also,it does not look like we're still using the earth as a conductor for economic reasons since the neutral wire is pretty much always provided.

What am I missing here?

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    \$\begingroup\$ See my answer to Earth ground portable generator. \$\endgroup\$ – Transistor Jan 28 at 17:35
  • \$\begingroup\$ Thank you for the insight. It looks to me like the only issue, would be the added complexity (and cost) for detecting the 1st fault to prevent the damage that could be cause by the 2nd one. Can you elaborate a bit more on the parasitic capacitances, since I don't feel like this would be harmful at all. \$\endgroup\$ – HatimB Jan 29 at 9:41
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Your missing the dielectric effect of coupling capacitance and risk of common mode noise like lightning. Humans and moist air have capacitance. And all dielectrics have a breakdown voltage to become conductors, including your finger interface which when touching another dielectric in series with a conductor like your stove top.

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  • \$\begingroup\$ If the transformer's secondary configuration is such that the coupling capacitance is low to earth, I still don't see how this current would be harmful at all. A human might feel a zip but they should be ok since the energy stored won't be substantial. Can you elaborate a bit more on this please? \$\endgroup\$ – HatimB Jan 29 at 8:41

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