Isolated Electricity Supplies - Why they are not used for everything

An isolated supply is not referenced to ground, and so the only way to get a shock from it is to touch both conductors at the same time.
They are not used everywhere as it is very difficult to ensure they remain isolated - any fault to ground anywhere would go unnoticed but convert the system to ground referenced.

Vidbb

Vidbb.com is a free music search engine from youtube. Watch and download free mp3 and mp4 from youtube.
Vidbb.com indexes only links to video materials, which are public and free of charge at youtube.com. Administration Vidbb.com not endorse any user submission, and expressly disclaims any and all liability in connection with user submissions.