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Clean Earth sockets

IronFreely
I’m just wondering about how clean earth sockets (Some of you may call these high integrity sockets) fit into the requirements of BS7671 in terms of their use in domestic homes.


One of my clients has asked me to look into the use of some clean earth sockets to be used to power audio equipment in their home studio, the basic idea is that a completely separate Earth helps eliminate what’s known as an earth hum on audio equipment caused by functional earth leakage of other equipment connected to the same circuit and disturbances originating from the suppliers earthing arrangement. The basic concept seems to be to insulate the cpc from the earth terminal of the socket outlet which then has its own independent Earth electrode, high integrity sockets seem designed to accept and insulate a cpc and a separate earth. 


My concern is that this sort of thing is usually used in a restricted access environment where only IT or audio engineers are going to be around and might be considered trained and competent to understand the risk of introducing an earth potential to the equipotential zone that is not in itself connected to the equipotential bonding. It wouldn’t be a problem if I could guarantee restricted access or that the socket would only supply class 2 equipment, but as this is a home studio it seems a bad idea to have an earthed metal casing of some piece of audio equipment that may be completely separate from all other earthing and bonding in the property? 


id appreciate your thoughts and advice please, I’m confident a separate clean earth will resolve the earth hum problem which I’ve seen work well in theatres (essentially restricted access) before but never in a domestic property.


Edit: I should add that the property is a TT property but because the street is a hodgepodge of TNS and TNCS (I have other neighbouring clients really close by) you should assume the gas and water pipe are throwing in a bit of PME related disturbance.
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    Chris Pearson:
    IronFreely:

    Thanks, this is the kind of advice that makes this forum a real gold mine, you just have to sift through the occasional troll suggesting the only issue is tinnitus! 


    That's not very polite!


    I return to the question about the amplitude of this noise. Has it been measured; and if so, is it at a level which is capable of being perceived? If either answer is "no" then any attempt to abolish the noise may be a waste of time and money.


    ETA: we are talking about a "domestic home" are we not?




    We are talking about a home studio, not what you might term an audiophile's "snake oil".


    Analogue interconnections that are used in some recording setups can be a minefield for very audible "hum", and it's sensible to have at least a structured approach to the mains. The same issues can plague live performance venues too.


    It is this particular "hum" which got me thinking about how I've resolved it in the past ... and then the "balanced output" consideration to help reduce the impact of the actual mains wiring by changing it from "common mode" to "differential mode".


    If there are any electric guitars in there, you do need to take care - especially with single-coil pickups - as any electric guitarist will tell you. Electric guitars need to be earthed to prevent "cracks" and "pops" that can happen when you touch (or let go of) the strings, but this makes them effectively "common mode" - so "common mode" single-phase mains hum can be difficult to eliminate.

     


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  • 0
    Chris Pearson:
    IronFreely:

    Thanks, this is the kind of advice that makes this forum a real gold mine, you just have to sift through the occasional troll suggesting the only issue is tinnitus! 


    That's not very polite!


    I return to the question about the amplitude of this noise. Has it been measured; and if so, is it at a level which is capable of being perceived? If either answer is "no" then any attempt to abolish the noise may be a waste of time and money.


    ETA: we are talking about a "domestic home" are we not?




    We are talking about a home studio, not what you might term an audiophile's "snake oil".


    Analogue interconnections that are used in some recording setups can be a minefield for very audible "hum", and it's sensible to have at least a structured approach to the mains. The same issues can plague live performance venues too.


    It is this particular "hum" which got me thinking about how I've resolved it in the past ... and then the "balanced output" consideration to help reduce the impact of the actual mains wiring by changing it from "common mode" to "differential mode".


    If there are any electric guitars in there, you do need to take care - especially with single-coil pickups - as any electric guitarist will tell you. Electric guitars need to be earthed to prevent "cracks" and "pops" that can happen when you touch (or let go of) the strings, but this makes them effectively "common mode" - so "common mode" single-phase mains hum can be difficult to eliminate.

     


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