Use of Schuko sockets in a UK home only for a HiFi system

Hello everyone,

This is my first post.

I have a question about using Schuko sockets in a UK domestic home.

But first, a bit of background might help.

I am a Member of the Institution of Mechanical Engineers. I didn't think my people would be very good at answering this question which is why I am here!

In more detail, I would like to use a Schuko socket to which only my hi-fi system would connect. The socket would be connected to a brand-new consumer unit with RCBO’s. There will also be surge protection. All will be done to the latest standards and specifications by a fully qualified electrician. The wiring diagram would be based on the one in this link: https://www.russandrews.com/images/pdf/MainsWiringGuide111023.pdf

I will also have a regular UK 3-pin socket. I am a reviewer for a HiFi magazine and want to do the above as the basis of an article on HiFi power supplies. 

So back to the question, is there any legal reason (or otherwise) that I can't use the Schuko socket in the UK? 

If the answer is “yes I can”, albeit with specific conditions, I'd like to quote that in my article/review. Especially if the Schuko supply sounds better than the UK 3-pin with fuse!

I am looking forward to your response.

Many thanks

Paul

Parents
  • OK, be prepared for some opinions on this one!

    Why a Schuko? Continental plugs and sockets don't have a great reputation for long term reliability. One of the design features of the 13A plugs over the earlier round pin variants was the advantage of having a flat contact area - it's much easier to maintain a good (low impedance) contact between two flat surfaces than between two rounded ones - for rounded ones to work well you need to match the curvature - which even if you get it precisely right in the first place (unlikely given manufacturing tolerances) they then change (typically in opposite directions) as the contacts wear. I can see that the omission of the fuse would reduce loop impedances every so slightly - but then I'm probably not convinced by the impedance of a.c. supply making much difference - surely the capacitors on the d.c. side of a properly designed audio PSU should be able to carry over any peaks and troughs in the audio demand - the mains supply drops to zero 100 times a second anyway, and no amount of fancy low impedance wiring is going to side step that.

    Schuko plugs aren't polarised (L-N can be reversed simply by inserting the plug the other way around) - for most modern appliances that shouldn't be an issue, but I wouldn't be happy using one to feed anything containing single pole fusing (e.g. a UK style 13A multiway socket into which fused 13A plugs would be inserted).

    Schuko sockets on UK installations are an on-going debate. BS 7671 specifies the use only of British Standard  BS 1363 (13A), BS 546 (old round pin UK) and BS EN 60309-2 (industrial style) for LV (main voltage) circuits, and further demands that they be shuttered for household use with a preference for BS 1363 ones. It does permit an exception to the first bit though for "a circuit having special characteristics such that danger would otherwise arise or it is necessary to distinguish the function of the circuit" - it depends on whether you can convince your electrician that you HiFi falls into that category. Any unfused socket will have to be on a suitably rated circuit though - 13A sockets are only permitted on 32A circuit because of the plug fuse -  for Schukos the circuit will have to be downrated to 16A (or maybe 20A).

    If it's just the fuse that's the issue - a UK style unfused round-pin socket (e.g. the old 5A or 15A ones of yesteryear) are still permitted and available and might be a more obviously conforming solution (plus are polarised).

    There are a few other things that don't quite ring true in that guide though. The wiring of the extra CU into the meter tails in the way they describe means the installation not longer has a single "main switch" that reliably switches off everything - usually held to be contrary to BS 7671 reg 462.1.201. The choice of a ring is 'interesting' - in other situations were mains borne noise is an issue radial circuits are normally preferred (to prevent the "loop" of the ring acting as an aerial). Running both legs of the ring together throughout the run reduces that effect, but a single cable is typically simpler and easier. Screened mains cables (e.g. BS 8436) can reduce interference pick-up too. On cables, their "woven" offering I suspect will cause all sort of problems with BS 7671 compliance, not only in terms of standards compliance (required by BS 7671) but it's construction of many separately insulated strands will cause all sorts of technical issues with short circuit protection. Even their description of what needs RCD protection seems to owe more to urban myth than wiring regs. Expect that your electrician will want to alter things a bit (with additional costs no doubt).

       - Andy.

Reply
  • OK, be prepared for some opinions on this one!

    Why a Schuko? Continental plugs and sockets don't have a great reputation for long term reliability. One of the design features of the 13A plugs over the earlier round pin variants was the advantage of having a flat contact area - it's much easier to maintain a good (low impedance) contact between two flat surfaces than between two rounded ones - for rounded ones to work well you need to match the curvature - which even if you get it precisely right in the first place (unlikely given manufacturing tolerances) they then change (typically in opposite directions) as the contacts wear. I can see that the omission of the fuse would reduce loop impedances every so slightly - but then I'm probably not convinced by the impedance of a.c. supply making much difference - surely the capacitors on the d.c. side of a properly designed audio PSU should be able to carry over any peaks and troughs in the audio demand - the mains supply drops to zero 100 times a second anyway, and no amount of fancy low impedance wiring is going to side step that.

    Schuko plugs aren't polarised (L-N can be reversed simply by inserting the plug the other way around) - for most modern appliances that shouldn't be an issue, but I wouldn't be happy using one to feed anything containing single pole fusing (e.g. a UK style 13A multiway socket into which fused 13A plugs would be inserted).

    Schuko sockets on UK installations are an on-going debate. BS 7671 specifies the use only of British Standard  BS 1363 (13A), BS 546 (old round pin UK) and BS EN 60309-2 (industrial style) for LV (main voltage) circuits, and further demands that they be shuttered for household use with a preference for BS 1363 ones. It does permit an exception to the first bit though for "a circuit having special characteristics such that danger would otherwise arise or it is necessary to distinguish the function of the circuit" - it depends on whether you can convince your electrician that you HiFi falls into that category. Any unfused socket will have to be on a suitably rated circuit though - 13A sockets are only permitted on 32A circuit because of the plug fuse -  for Schukos the circuit will have to be downrated to 16A (or maybe 20A).

    If it's just the fuse that's the issue - a UK style unfused round-pin socket (e.g. the old 5A or 15A ones of yesteryear) are still permitted and available and might be a more obviously conforming solution (plus are polarised).

    There are a few other things that don't quite ring true in that guide though. The wiring of the extra CU into the meter tails in the way they describe means the installation not longer has a single "main switch" that reliably switches off everything - usually held to be contrary to BS 7671 reg 462.1.201. The choice of a ring is 'interesting' - in other situations were mains borne noise is an issue radial circuits are normally preferred (to prevent the "loop" of the ring acting as an aerial). Running both legs of the ring together throughout the run reduces that effect, but a single cable is typically simpler and easier. Screened mains cables (e.g. BS 8436) can reduce interference pick-up too. On cables, their "woven" offering I suspect will cause all sort of problems with BS 7671 compliance, not only in terms of standards compliance (required by BS 7671) but it's construction of many separately insulated strands will cause all sorts of technical issues with short circuit protection. Even their description of what needs RCD protection seems to owe more to urban myth than wiring regs. Expect that your electrician will want to alter things a bit (with additional costs no doubt).

       - Andy.

Children
  • I really appreciate your comprehensive response.

    Why a Schuko?
    a UK style unfused round-pin socket (e.g. the old 5A or 15A ones of yesteryear)

    A good spot, but is not available on ready-made "Audiophile power cables", hence Schuko.

    Schuko plugs aren't polarised (L-N can be reversed simply by inserting the plug the other way around)

    I will be using ones where the L and N are marked.

    single "main switch"

    I will have one after the smart meter before the Henley splitter blocks feeding to the consumer units.

    their "woven" offering I suspect will cause all sort of problems with BS 7671 compliance

    I won't be using their woven cable. I will be using a screened cable.

    Expect that your electrician will want to alter things a bit (with additional costs no doubt)

    Thankfully the electrician is a bit of an Audiophile, and the price for the work (I've checked) is very reasonable. Phew!

  • Thank you for such a comprehensive response.

    a UK style unfused round-pin socket

    Good spot but they aren't easily available on ready-made Audiophile power leads.

    Schuko plugs aren't polarised (L-N

    Mine are marked.

    a single "main switch"

    I will have a main isolator switch after the smart meter before the Henley blocks that feed both consumer units.

    "woven" offering

    I will be using screened cable.

    Expect that your electrician will want to alter things a bit

    Thankfully my electrician is a bit of an Audiophile, and his cost is very reasonable (I have checked). Phew!

  • Good spot but they aren't easily available on ready-made Audiophile power leads.

    Oooh? gap in the market for a new product??? Could be a money spinner!

       - Andy.