In article ,
Clive Mitchell wrote:
With standard unbalanced connections, removing the mains earths from
everything but one is usually the best way to go. Of course I can't
recommend it on here...

Oh dear. There appear to be people still doing it.

So you have equipment with floating mains earths and you have earthed
equipment. A fault occurs, someone bridges the two pieces of equipment
and gets killed.

No - it earths via the screen on the connecting cable.

You NEVER disconnect the mains earth from equipment. It's a very
misguided bit of technical folklore that has already caused several
serious accidents. The correct way to lift ground on a balanced system
is to disconnect the cable screen at the source end of the cable so that
the input device is providing the screen reference.

Balanced system? With correctly designed balanced connections you won't
get an earth loop, even with separately earthed equipment casings. That's
why it's used on pro equipment. I'm talking about unbalanced domestic.

If you do disconnect equipment earths in the way you've described and
someone does die you will be held accountable for their death and will
face a charge of manslaughter.

Yeh yeh... Can you give an example of where this has happened?


Here's a video of a singer experiencing a potential difference between
the microphone and the strings of her guitar.

I can't access that video. However, most of these sort of accidents happen
because the location mains supply is faulty. So the correct approach was
to use *mains* isolating transformers. And always was. Although these days
RCDs take care of the safety angle.

--
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