In article ,
Don Pearce wrote:
It shouldn't. Assuming you only have a single safety earth connection to
the common signal ground return, the whole thing could be left to float
at whatever induced mains voltage happens to occur (including half mains
from filters or even a full contact to the live). It won't make any
difference although I'd be rather leery of actually touching any of the
kit if bringing your hand to within close proximity generates even the
slightest hint of mains hum.

These days most grounds are heavily compromised by EMC from switching
power supplies coupled in through the Y1 capacitors. Hang enough of
those on a single circuit and eventually you can even trip the RCD
breaker.

Which was the theory behind running my AV ground right back to the house
earthing point, rather than CU earth.

--
*Why don't sheep shrink when it rains?

Dave Plowman London SW
To e-mail, change noise into sound.