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Which end of the power cord should the braided shield be grounded to?
Which end of the power cord should the braided shield be grounded to?
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Old 3rd November 2017, 02:52 AM   #1
Lot49 is offline Lot49  United States
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Default Which end of the power cord should the braided shield be grounded to?

I'm building a couple of power cords using Furutech plugs and cable. The cable has a braided copper shield which, as I understand it, should be connected to the ground wire at one end of the cable―either the device end or the power source end. Or maybe both, I don't know. Any suggestions would be appreciated.
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Old 3rd November 2017, 02:58 AM   #2
audiopro is offline audiopro  Canada
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Power source (male) end only.
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Old 3rd November 2017, 12:32 PM   #3
DF96 is offline DF96  England
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My suggestion is to avoid shielded power cords. It is difficult to think of a circumstance in which they will actually do anything useful for audio.
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Old 3rd November 2017, 12:37 PM   #4
kaputt is offline kaputt  Germany
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Will they cause harm?
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Old 3rd November 2017, 12:48 PM   #5
infinia is offline infinia  United States
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I'd call FuruT Tech support and ask them their opinion. I'd bet they probably have marketing type interns for tech support e.g. of course they'll probably up-sell you the "correct wire/cable" for this connection.
me? id connect it at both ends just for extra bit of fault protection only.
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Old 3rd November 2017, 12:55 PM   #6
simon7000 is offline simon7000  United States
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Quote:
Originally Posted by DF96 View Post
My suggestion is to avoid shielded power cords. It is difficult to think of a circumstance in which they will actually do anything useful for audio.
They add about 6dB of coupling between the mains leads. That reduces differential mode noise. Not much use on common mode.

In total noise reduction it has a bit of other effect as measured. However as the inductance of the ground connection is so high that had almost nothing to do with anything of practical value.

If the shield is grounded to the case it acts as an antenna and can increase the EMI noise level.

If connected to the safety ground, it will couple any noise found there into the common mode AC line EMI.

So the answer is it does not need a connection, but the AC safety ground side is a much better choice if you must ground it.
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Old 4th November 2017, 12:34 AM   #7
Speedskater is offline Speedskater  United States
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Because a hi-fi component's power cord can act as an interference antenna (transmitting or receiving) my feeling is to attach it only at the hi-fi component end. That way it will act as an extension of the chassis shield.
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Old 7th November 2017, 03:08 PM   #8
Kay Pirinha is offline Kay Pirinha  Germany
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What a luck that this antenna ends exactly at the wall receptacle.


Best regards!
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Old 7th November 2017, 03:13 PM   #9
Lot49 is offline Lot49  United States
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Thanks to all who responded. Lots of opinions!
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Old 8th November 2017, 01:32 AM   #10
Speedskater is offline Speedskater  United States
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Quote:
Originally Posted by Kay Pirinha View Post
What a luck that this antenna ends exactly at the wall receptacle.
Best regards!
Well the interference antenna doesn't end at the wall receptacle. But the other interference antennas (I mean the other hi-fi components power cords) are all nearby.
Jim Brown often writes about these kinds of interference problems:

Antenna Action The most fundamental cause of radio interference to other systems is the fact that
the wiring for those systems, both inside and outside the box, are antennas. We may call them
"patch cables" or "speaker cables" or "video cables" or "Ethernet cables," or printed circuit traces,
but Mother Nature knows that they are antennas! And Mother Nature always wins the argument.


and about power cords and Ham radio:

Power Supply and Control Wiring can also act as antennas. When I bought the house I owned in
Chicago, I upgraded the electrical wiring and put all of it in steel conduit (EMT). This shielded the
wiring, so that only the short power cords between equipment and the wall outlets could act as
antennas. The house I recently bought in California is wired with no conduit, using unshielded
parallel conductors. Thanks to its length, and the fact that it is not shielded, this wiring acts as an
effective receiving antenna for the RF I am transmitting, and an effective transmitting antenna for
the RF trash generated by computer equipment, power supplies for low voltage lighting fixtures,
and even battery chargers.
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