Isolating transformer principle

[KeenPensioner]

As can be seen from my profile I am not a qualified electrician but I'm studying in my own time just for the sake of it. Everywhere I look for info on isolating transformers I get something like this "This means that the isolation transformer secondary side must not be grounded. It would create a physical connection between the primary and secondary transformer side." or "no return path to earth from transformer secondary". I don't get that. If you look at the attached image, is there not a "return path" with 0.24A passing through the body? Perhaps I just don't understand how neutrals/earths work! Any help would be appreciated.

 

[Lucien Nunes]

is that not "reduced low voltage" as in 55-0-55 site transformers?

Yes that too, I actually had in mind small ELV power supplies for electronic goods. E.g. sitting on my bench are half a dozen 12V SMPSUs of which some have earth-referenced outputs and some don't. I didn't want to over-complicate things by mentioning that it's not the transformer secondary itself but the rectified output that is earthed in those.

 

[Lucien Nunes]

is that not "reduced low voltage" as in 55-0-55 site transformers?

Yes that too, I actually had in mind small ELV power supplies for electronic goods. E.g. sitting on my bench are half a dozen 12V SMPSUs of which some have earth-referenced outputs and some don't.

 

[KeenPensioner]

Lucien Nunes explains it well to me as an amateur. If I get it now the image below shows what I think he means. Thanks again to everyone