Dedicated mains feed

I had a separate radial installed with 3No. 32a RCBOs with 6mm2 cable. However, for the wall wart power supplies, I left them plugged into the existing electrical circuit.

Will you be using the SWA cable inside the house only?

The cable will be mostly outside, although may come in via part of the loft for about 10 meters

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GM,
Just a few thoughts, starting with where the power enters your building.

  1. Split the feed and install a second consumer unit.
  2. I’ve listened to all of the available MCB’s and the MK’s were easily the most tuneful. Interestingly, I’ve found the 15A to be slightly better than the 32A version. However, I think your electrician could insist on fitting an RCBO (in accordance with the latest regulations) which don’t sound as good. Speak to him about installing a circuit protected by RCD’s which is marked for use only with your HiFi system and by “experienced and competent personnel” (or something along those lines!), although I’ve got a feeling that this is also outlawed these days.
  3. Although it’s difficult for me to know for sure, I’m 80% certain that the optimal CSA of the single radial circuit is related to the length of the circuit. If the circuit is under about 8m, a 4mm2 radial will probably be the most musical. At 12m length, I’ve found 6mm2 to be better. This is based on lots of experimenting in several different rooms and buildings. I’ve found 10mm2 radials to sound very impressive, with a tight and powerful bass, but overall not very musical. However, I’ve never needed to go beyond about 12m and I wouldn’t be surprised if at say 14m+ a 10mm2 radial worked well. My advice would be to fit all three sizes and choose the best one for your particular arrangement. The additional cost will be minimal in comparison to the cost of labour.
  4. I’ve compared lots cable types, but unfortunately I’ve never tried an armoured cable. However, of the types I’ve tried, a simple T&E works much better than cables which twist the cores. Rather than gamble, it might be safer to ask your electrician if it’s ok to use T&E inside suitable trunking.
  5. Fit just one single socket and power your system using a good extension block (not necessarily expensive!)

Overall though, I think the best recommendation would be to KISS! Complex power circuits can sound very impressive, but they soon become tiresome. Simple circuits don’t sound impressive, but they can have a musicality which seems to get better by the month.

Many thanks indeed for your response

  1. yes, this will be a separate CU just for the HiFi - sorry if it wasn’t clear
  2. I suspect it will have to be RCBO’s for 18th Edition, especially as I want it certified - but I will have the discussion. 16A would be fine for my gear, and in fact safer. Do you think a 16A RCBO would sound better than a 32A? I suppose I could always try a different one after it’s run in for a while and I’m used to it.
  3. I’m going to need to go about 25m+ for this run. All the Naim recommendations seem to be 10mm with 6mm as an option 2. I do take your point, and it’s not the cost, but don’t really want to run 3 cables side by side across my house - as it took me long enough to justify 1 cable only slightly hidden. I don’t know what the current conduit options are, but typically with all the visible joint, I prefer SWA. To me, it doesn’t matter if it’s a harder job to install, as it’s the end game that matters, and that’s how it looks and how it sounds.
  4. I’m not entirely sure if the cores that are twisted, or just the strands, or both or neither. I’ll have the discussion to see what the options are, thanks. What I wanted to say was not single core, which perhaps isn’t even available at 10mm.
  5. It is my main intention to use only one of the double sockets, but thinking of going for double for 2 reasons. Firstly there will be more room in the box to fit the thick cable, and Secondly I have seen some people mention that they often plug their Amp into the wall socket rather than block. So just giving myself all options.

Can you expand on what you mean by a Complex power circuit?
Many thanks!

tbh, I’ve not tried 16A vs 32A RCBO’s, but it’s easy to switch them over at a later date.

Given the length of your run, I think 10mm2 would be most appropriate!

By “complex”, I mean anything other than a single t&e. eg multiple runs with separate circuit protectors etc.

Good luck with your project :+1:

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Ive used 6 x 10mm circuits from their own mem consumer unit. The consumer unit is protected by a 100A 30mA rcd, and each circuit is on a 32A mcb. The earthing is star wired and the main incoming house fuse is 100A.
Before this I had tried both a single 6mm circuit and multiple 6mm circuits. The multiple 10mm circuits was far better sonically to my ears.
Ive now had all this installed for over 10 years and the system really sings. It takes a few weeks to burn in and sound open and flow easily but it really is so worthwhile.
Hope you thoroughly enjoy the results you get.

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That’s a lot of runs. I may struggle with that, as I don’t want that many cables showing on the front of my house, so would need to rethink a lot.

I think I will start with a 32A RCBO. Although a 16 would suffice, I’m wondering if the throughput resistance of a 32 would be less than the 16 - don’t really know.

I did try and call Naim for advice today, but there were not able to provide any details. I will try my dealer next week.

Many Thanks

Naim support used to be happy to offer advice about UK mains arrangements, but with the individuals involved having been replaced by a more call-centre type support service I suspect this may have been lost. FWIW this is the spec that Naim (in the form of Steve Hopkins) recommend to me when I asked:

Split meter tails to add a separate consumer unit. Do not run this from a spare way in the main CU, and do not run the earth cable via the main CU.
Use a single 32 Amp Type C MCB (or whatever your electrician needs to use to conform to current regs.)
Run a single 10mm T&E cable to an unswitched socket. (He said they had tried multiple runs and found a single run to be better).

No doubt others will have different views on what works for them, but that was Steve’s suggestion, based, I believe, on trials when they wired the demo room at HQ.

That’s what I have, and have done for over 20 years, albeit with a 50amp breaker. It’s 10mm2 SWA and runs round the house under the flowerbed.

Thanks @ChrisSU

@anon4489532 one question I do have is around the socket end of the SWA. Did you earth the outer steel wire, and just earth the CU end? - if you remember that finer detail 20 years ago :grinning_face_with_smiling_eyes:

At the time I had NDX/282/200DR, I suspect a bigger system with more heavy duty PSUs would have led Steve to suggest the bigger MCB.

Sorry, I don’t know. It’s all in a junction box on the outside of the house.

@anon4489532 I agree. I was going to ‘like’ your post, but felt a response was more fulfilling. Can you like this post so I can have one of your rare acknowledgments?

Thanks all. Looks like I have another month wait for my new NDX2, so if I can get it in before, that will be great. Chance to take everything apart with a thorough dusting :blush:

The bar is, unfortunately, set considerably higher.

Totally understand. I was just trying to sneak one in.

Good plan. I had the same problem with having to go from one side of the house to the other. I’ve got a ~25m run of 10mm2 T&E that goes from the dedicated CU in the garage, up through a built in wardrobe to the loft and drops down the opposite outside wall to the lounge socket via conduit. Still one of the best VFM upgrades I’ve done.

Thanks James.

Just failed at first hurdle - the electrician I was recommended to contact is too busy, having 60+ jobs lined up already. He must be really good, but doesn’t have time to fit me in. Here’s hoping 2nd recommended Sparky is available…

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I found the same…the sound stage is bigger and more open with dedicated spurs for each power supply . Maybe to some ears the sound being more integrated is preferable via. a single spur?

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