On Wed, 29 Nov 2017 13:09:28 +0000, Dave Plowman (News) wrote:

In article
,
D.M. Procida wrote:
If you read uk.d-i-y, you may have seen a thread ("This appliance must
be earthed") about Dutch mains sockets, which are often unearthed.

If I plug a Cyrus 1 amplifier (which has an extremely metal case and a
stern label saying "This appliance must be earthed") into an unearthed
socket, do I risk death by electrocution, or worse, poorer sound
quality?

The warning simply means the construction doesn't conform to the EU
requirements of a device with metal parts and no earth. Assuming it is
in good condition, I doubt you'd get electrocuted by it with no earth.

Noise figures as part of an installation may be poorer, though.

It makes sense to hard earth the amplifier and utilise the
'interconnects's signal earths to provide safety earthing of the
peripheral sources (TT. tuner, legacy optical disk player and tape deck
(s)). However, take note that phono plugs can sometimes prove ineffective
in earthing due to mismatches in the socket/plug dimensions so you need
to take care in your choice of phono plugs if you're going to rely upon
these interconnects to act as safety earths for your peripherals.

One sure fire way to provide safety earthing on peripheral kit
independent of signal earthing is to use a pair of 6A rated silicon
diodes wired in anti-parallel with a 100 ohm resistor and a 100nF
capacitor (all in parallel) in series with the safety earth connection
with a 1A safety fuse in each individual peripheral's mains supply
connection.

Under normal operating conditions, the signal earths will short out the
100 ohm resistor and the diodes high impedance at sub 500mV peak
voltages, effectively leaving the 'safety earth' connection in a state of
'disconnect' whilst still providing an effective safety earth in the
event of a fault.

One final note, it's good practice to power all of the components of a
"separates" Hi-Fi setup from a single ring main socket[1] via a quality
mains multi-socket extension lead or specialist connection strip. This
neatly isolates ground loop currents that can occur when using different
sockets on a ring main due to induced currents from heavy loads such as
washing machines, toasters, kettles etc.

[1] You can regard double/triple socket outlets (as well as adjacent
single/double/triple socket outlets) as being effectively a single outlet
in this case which can neatly do away with the need for a multi outlet
mains lead extension socket.

--
Johnny B Good