"Dave Plowman" <dave.sound@argonet.co.uk> wrote in message
news:4c1109cf2edave.sound@argonet.co.uk...
> > Would you know if the Earth was needed or better left off? Do you know
> > which way the current is flowing and why there is a positive and
> > negative in AC current.
>
>  There's not. There's a line and neutral. Nor should an earth ever be left
> off - if it's causing a ground loop there are other ways of sorting this.
>

What about removing the earth line from an Oscilloscope so that fault finding can be done
on a switched mode power supply, or live chassis TV?

Isolation amplifiers are so expensive and unreliable.